This ancient predator had two spiny appendages sticking out of its face. This creature Anomalocaris canadensis may have been the freakiest thing to ever haunt the sea. For decades, scientists thought it used those strange limbs to snatch trilobites off the seafloor. The beast could then crush and eat these crunchy snacks. But a new study hints that A. canadensis instead used its spiny limbs to swiftly hunt soft prey. 



Researchers shared their new findings on July 12. The work appeared in Proceedings of the Royal Society B.





A. canadensis means the abnormal shrimp from Canada. It prowled the seas roughly 500 million years ago. Only about as long as a housecat, it still was one of the biggest animals of the Cambrian Period. (The Cambrian ran from about 540 million to 485 million years ago.) That makes A. canadensis one of the earliest top predators.





These sea monsters were like the orcas or great white sharks of their time, says Jakob Vinther. He did not take part in the new study. But he is a paleontologist at the University of Bristol in England. 



Some researchers thought A. canadensis hunted another iconic Cambrian critter the trilobite. Thats because people have unearthed lots of fossils of injured trilobites. This hinted that something had attacked them. A. canadensis became a prime suspect.



But Russell Bicknell wasnt so sure. After all, trilobites have hard, thick exoskeletons. And no one had shown that A. canadensis could crack that armor.



Bicknell is a paleobiologist. He works at the American Museum of Natural History in New York City. He was part of a team that set out to learn if A. canadensis really could have crushed and chowed down on trilobites.



This is a closeup of an A. canadensis fossil. It was found in the Burgess Shale of Canada. The fossil shows the creatures head and curled front appendages.Allison Daley


Pinning softies with its spikes



The researchers compared the ancient creatures bendy appendages to those of modern arthropods. These animals include todays insects, spiders and crustaceans. Bicknells team also built computer models of the limbs on A. canadensis. Using those models, the team tested the limbs toughness, range of motion and best swimming position.



The ancient spiky limbs would have been good at grabbing prey. In that way, A. canadensis may have hunted much like todays whip spiders. But the limbs of A. canadensis probably were too fragile to attack armored prey. Those would have included trilobites.





Plus, A. canadensis would have moved most efficiently when its appendages were stretched out front. (Think of how Superman holds his arms while in flight.)



Together, these results suggest that A. canadensis was best suited for chasing soft creatures swimming through the water. It would have snagged prey in its spiky clutches, Bicknell says. It was going to absolutely pincushion something soft and squishy.

Mythical mermaids are often known for their fishy tails and alluring songs. But if you were underwater with one, her tunes wouldnt sound quite like they do in the movies. And you might struggle to understand the words as Ariel or her other mermaid friends burst out singing.



Even next to a mermaid, the song would sound muffled and would seem to come from all around, says Jasleen Singh. You could still make out what she is saying, but it would sound fuller with less clarity, Singh says. She studies human hearing at Northwestern University in Evanston, Ill.





If mermaids existed, and if they sang and talked to one another, their hearing and sound-making setups might resemble marine creatures features instead of humans. To understand why, you have to start with the basics of sound and hearing.



Explainer: How the ears work



Sound is produced when an object vibrates. Touch your throat while you talk, and you can feel your vocal cords vibrating inside your neck. These vibrations can travel through gases, liquids and solids. In each medium, atoms and molecules get pushed around by a sound sources back-and-forth motion. These particles bump into each other in a rippling pattern of waves. Like a line of falling dominoes, the colliding particles spread sound.



Human hearing starts with sound waves entering the air-filled space in each earhole. The waves vibrate the eardrum, which wiggles three little ear bones. One of the bones taps on a snail-shaped structure in the inner ear called the cochlea. This fluid-filled structure converts the vibrations into electrical signals that the brain understands as sound.



Underwater, its a different story. Since water plugs your ears, you rely on sound waves directly vibrating the skull. This happens on land too, but it works better below the waters surface. Thats because water and bone have similar densities. When sound waves gently rattle the skull, that is directly stimulating the inner ear the cochlea itself, Singh says. This is called bone conduction. We humans, however, are much more attuned to the sound waves striking our eardrums. As a result, the sound quality of bone conduction is not as good as regular air conduction.



Plus, its difficult to figure out where a sound is coming from underwater. On land, if someone starts talking on your right side, sound waves hit your right ear before your left. This slight variation in timing helps your brain find the source of a sound. But sound travels much faster in water than in air. Thats because the particles that make up liquids are closer together. In water, there is virtually no time difference between sound hitting each ear. That makes underwater noise sound very full, like its coming from everywhere.









Our sea-dwelling relatives



To hear their friends talk and sing properly, mermaids might have evolved hearing structures more like aquatic animals.



Marine mammals, such as whales, dolphins and seals, hear in a way very similar to humans, notes Colleen Reichmuth. A biologist, she studies marine mammals at the University of California, Santa Cruz. These creatures have cochleae. They also have ear bones and eardrums, though not always functional. And they have evolved some adaptations to help them hear under the sea.





The lower jaw of dolphins and some whales contains fat that directs sound to the bony middle ear. This fat has a special chemical composition that makes it really suitable for transmitting acoustic waves, says Laela Sayigh. Shes a marine biologist at Hampshire College in Amherst, Mass., and Woods Hole Oceanographic Institution in Massachusetts.



Some marine mammals, such as seals, have convertible ears. On land, the animals can open ear holes to pick up sound waves traveling through air. But when diving, their ear tissue swells with fluid, plugging the holes. The fluid-filled ears help transfer sound from the water to the cochleae.





Those features could help a mermaid hear her friends songs more clearly. But if mermaid voices were more like those of marine mammals, their vocal systems could get a major upgrade, too.



Whales, dolphins, seals and other marine mammals can sing underwater, creating complex noises with musical notes or rhythms. They produce sound by passing air along tissues to vibrate them, similar to a humans voice box. But unlike people, who must breathe out to make noise, many of these sea creatures dont need to expel air from their mouths or blowholes to produce sound.



Underwater, air is a precious commodity, says Joy Reidenberg. If whales exhaled when using their voices, they would have to keep resurfacing for more air. That would interrupt their lengthy songs, Reidenberg says. She studies animal anatomy at the Icahn School of Medicine at Mount Sinai in New York City.



Instead, whales and dolphins can move air around in their bodies and even reuse it. This air recycling system would certainly help a mermaid sustain conversation or song below the surface, Reichmuth says.



For a voice that really carries, mermaids might be built like baleen whales. These whales, which include humpbacks, have huge vibrating structures in their throats that toss out sound. Some can make noises so loud and low-pitched too low for humans to hear that the songs could potentially travel more than 1,000 kilometers (600 miles) in the ocean. (Lower-pitched sound waves lose less energy when traveling through water than higher-pitched ones.)



Humpback whales sing beautiful, lengthy songs. But they dont need to breathe out of their mouths or blowholes to do it. These whales recycle the air supply in their bodies and can stay submerged for nearly an hour. Craig Lambert/iStock/Getty Images Plus



Something sounds fishy



A mermaids mammal upper half may not be the only part that could make or hear sounds. Crustaceans and fish are known to make quite a ruckus, too. In fact, snapping shrimps, typically around four centimeters (1.5 inches) long, are some of the loudest creatures on Earth. As the name implies, these shrimp snap one of their claws to produce a colossal sound.



Many fish use a similar method to make noise. They click or rub their bodys bony structures together. Sea horses, for example, produce clicks by knocking the tops of their skulls into the horns on their heads. They do this when wooing a mate.



You can think of it like clicking your teeth together, says Audrey Looby. A marine ecologist, she studies fish at the University of Floridas Nature Coast Biological Station in Cedar Key.



Other species can use their muscles to vibrate an internal organ, like playing a drum. Some fish can even communicate by expelling air out their backside, Looby says. Essentially, fish communicating through farting. And they have special cells lining the sides of their bodies that can sense vibrations in the water, helping them to hear.



If you met a mermaid, she might have both fish-like and mammalian structures to communicate with her underwater friends. Motion-detecting cells may line her tail, and her ears may work like a seals to hear both in and out of water. She would probably recycle her bodys air supply to talk and sing without having to keep resurfacing. But her conversations may also be sprinkled with teeth chattering, clapping and even farting.

Coral (noun, CORE-uhl)



Corals are tiny marine animals that live in clustered groups on the ocean floor. Each group contains hundreds or even thousands of individuals. An individual coral animal is called a polyp. Polyp describes a kind of body shape a long, thin body shape that often flares at one end like a vase. The corals base attaches to a solid surface, such as a rock. At the top, stinging tentacles sprout around the mouth and capture plankton drifting past.





Many coral species build porous structures called coral reefs. The kinds of coral that build reefs are often called “hard coral, stony coral or reef-building coral. The polyps of reef-building corals secrete chemicals that harden around their soft bodies. When polyps die, this hard structure remains behind and new polyps may attach to it. This cycle repeats over time, forming elaborate structures with different shapes. For example, the staghorn coral (Acropora cervicornis) gets its name from its antler-like prongs. Brain coral (Diploria labyrinthformis) looks you guessed it like a brain.



Most reef-building corals contain zooxanthellae photosynthetic microbes that live inside coral polyps. Just like plants, zooxanthellae use sunlight to make sugar, which the coral eats. In return, the zooxanthellae get protection inside the reef. But not all corals make coral reefs. Soft corals refer to non-reef builders. These are often mistaken for plants since they can sprout wildflower-like clusters of bendy, whiplike animals with feather-like tentacles.



Coral reefs are important marine ecosystems. They make up less than one percent of the entire oceans floor. But they are home to nearly one-quarter of all marine species. For example, over 4,000 fish species make their home among the coral reefs. Hundreds of other species, from shrimp to sea stars to sea grass, also live in coral reef ecosystems.   



But corals are vulnerable to changes brought about by human activity. For example, excess fertilizer washes from crop fields into our oceans, fertilizing marine algae. That causes algae growth, which clouds the water and starves the sun-loving zooxanthellae and their coral buddies. Since many other life forms depend on corals for food, shelter and other needs, the coral death can upend life in these ecosystems and beyond.



In a sentence



Scientists saved some sick coral by treating them with amoxicillin a common antibiotic.



Check out the full list of Scientists Say.

Scientists may have just found the longest gravitational waves yet.



Gravitational waves are ripples in the fabric of spacetime. Kicked up by massive objects, they roll through the universe like water waves on the surface of the ocean. The newfound gravitational waves are light-years long. That means it would take years for light to travel the distance of a single ripple.



Explainer: What are gravitational waves?



Whats more, these waves wash through the universe nonstop. They constantly jostle Earth and the rest of our galaxy.





Pairs of huge supermassive black holes are thought to trigger these waves. Those black-hole behemoths sit at the centers of galaxies. Scientists think that when two galaxies collide, their black holes pair up and orbit each other. This action could churn up those gravitational waves in spacetime.



Indeed, across the universe, galaxies often mingle and merge. As they do, scientists had suspected their supermassive black holes would orbit each other. In the process, these black holes would give off gravitational waves. In fact, they should pump out waves nonstop for millions of years. Many supermassive-black-hole pairs in the many merging galaxies across the cosmos would send out their spacetime ripples at once. This, scientists thought, should create a constant mishmash of very long gravitational waves.



Explainer: What are black holes?



On June 28, researchers shared the first clear evidence of such a background of gravitational waves. Those data came from several teams around the world.



Scientists must confirm that the newly spotted waves are real and that they do come from pairs of huge black holes. But if so, its miraculous, says Meg Urry. Shes an astrophysicist at Yale University. Thats in New Haven, Conn.



Confirming the new findings would offer the first proof that the biggest black holes in the cosmos can spiral into each other and merge. Its extremely interesting, Urry says. The reason? We have essentially no handle on what the most massive black holes are doing.



Catching a new kind of wave



Since 2015, scientists have spotted lots of gravitational waves. Some have come from smashups between neutron stars. Others have come from colliding black holes. But the black holes in those collisions were small, by cosmic standards. Most were less than 100 times the mass of our sun. Their smashups created blips of gravitational waves that detectors on Earth felt for mere fractions of a second.



Those supermassive black holes thought to cause the newfound gravitational waves are entirely different beasts. Each can have the mass of millions or billions of suns.



The Earth is just randomly bumping around on this sea of gravitational waves, says Maura McLaughlin. Shes an astrophysicist at West Virginia University in Morgantown.





Compared to the gravitational waves seen before, this is a very different sort of thing, says Daniel Holz. This astrophysicist works at the University of Chicago, in Illinois. He and others have used the LIGO detector to spot gravitational-wave blips from small black-hole smashups.



To find waves from supermassive black holes required a whole new technique.





Peering at pulsars



For this new research, scientists looked to objects called pulsars. Theyre spinning remnants of exploded stars. Like celestial lighthouses, pulsars emit beams of radio waves as they spin. Their beams sweep past Earth at regular intervals. Those flashing beams of radio waves are picked up, like the precise ticks of a clock, by telescopes on Earth.



Gravitational waves can stretch and squeeze the space between a pulsar and Earth. In that way, such ripples in spacetime could cause a pulsars ticks to reach Earth early or late. Scientists have now used this effect to search for the gravitational waves from supermassive black holes as they roll through space.



A project called NANOGrav has watched dozens of pulsars for 15 years. (NANOGrav is short for North American Nanohertz Observatory for Gravitational Waves.) The NANOGrav team now thinks it finally has evidence of gravitational waves from pairs of supermassive black holes. The team just shared its findings in Astrophysical Journal Letters.



Scientists searched for gravitational waves by watching dozens of spinning stars called pulsars. Here, each pulsar is shown as a blue dot against a gray illustration of our Milky Way galaxy. The yellow star (near center) shows where Earth sits in the Milky Way.NANOGrav


Its really invigorating stuff, says Michael Keith. Hes an astrophysicist at the University of Manchester in England. Hes also a member of the European Pulsar Timing Array, or EPTA.



The EPTA team spent an even longer time staring at pulsars about 25 years. We were starting to think maybe the signal is just so weak, well never ever find it, Keith says. But like NANOGrav, EPTA has now seen evidence for gravitational waves altering pulsar signals.



EPTAs results have been accepted in the journal Astronomy and Astrophysics. The European group teamed up with researchers from the Indian Pulsar Timing Array to do the work. Teams from Australia and China have now shared evidence for gravitational waves from pairs of supermassive black holes, too.



Astronomers used a variety of radio telescopes to view pulsars in their hunt for gravitational waves. One of those telescopes was the Effelsberg radio telescope (shown) in Germany.Tacken, MPIfR


Its not over yet



Some scientists had thought that supermassive black holes in merging galaxies would never draw close enough to merge. In that case, they wouldnt give off gravitational waves like the ones scientists think they have now observed.



Its actually been a sore spot for our field for many years, Chiara Mingarelli says. Mingarelli is an astrophysicist on the NANOGrav team. Shes based at Yale University.



But if the new gravitational-wave signal is real, it seems to be stronger than expected. That suggests that supermassive black holes spiraling into each other are common. This, in turn, hints that mergers between such black holes also are common.



But none of the teams sharing new data say they have for sure detected gravitational waves from huge black-hole pairs. They just say theyve found strong evidence for this. Thats because each of their observations comes with some uncertainty. In the future, the separate teams plan to join forces. Combining their data may help confirm the detection.



Still, even if the waves are real, its possible they dont come from pairs of monster black holes. Such huge black holes appear to be the simplest explanation. Still, researchers cant rule out a more exotic one. For example, the ripples might have arisen from the fast expansion of the universe just after the Big Bang.



Learning more about supermassive black holes is key to understanding the galaxies that host them. So whatever the source of the potential new gravitational waves, their future study is bound to have ripple effects.

Objective: To measure the effect of temperature on the rate of a chemical reaction



Areas of science: Chemistry, science with your smartphone



Difficulty: Easy intermediate



Time required: 25 days



Prerequisites: None



Material availability: Readily available



Cost: Very low (under $20)



Safety: Adult supervision may be needed when working with hot water solutions



Credits: Andrew Olson, PhD, Science Buddies; edited by Svenja Lohner, PhD, Science Buddies






You may have seen a television commercial for Alka-Seltzer tablets or heard one of their advertising slogans: Plop, plop, fizz, fizz, oh what a relief it is! When you drop the tablets in water, they make a lot of bubbles, like an extra-fizzy soda, as shown in the main image up top (Figure 1). And like a soda, the bubbles are carbon dioxide gas (CO2). However, with Alka-Seltzer, the CO2 is produced by a chemical reaction that occurs when the tablets dissolve in water.





Alka-Seltzer is a medical drug that works as a pain reliever and an antacid (antacids help neutralize stomach acidity, such as heartburn). The pain reliever used is aspirin and the antacid used is baking soda (sodium bicarbonate, NaHCO3). To take the tablets, they should be fully dissolved in a glass of water. When sodium bicarbonate dissolves in water, it dissociates (splits apart) into sodium (Na+) and bicarbonate (HCO3) ions. (An ion is a molecule that has a charge, either positive or negative.) The bicarbonate reacts with hydrogen ions (H+) from citric acid (another ingredient in the tablets) to form carbon dioxide gas and water. In other words, carbon dioxide gas is a product of this reaction. The reaction is described by Equation 1 below:



Equation 1.3HCO3 + 3H+ 3H2O + 3CO2



So how is temperature related to this bicarbonate reaction? In order for the reaction shown above to occur, the bicarbonate ions have to come into contact with the hydrogen ions. Molecules in a solution are in constant motion and are constantly colliding with one another. The hydrogen and bicarbonate ions must collide at the right angle and with enough energy for the reaction to occur. The temperature of a solution is a measure of the average motion (kinetic energy) of the molecules in the solution. The higher the temperature, the faster the molecules are moving. What effect do you think temperature will have on the speed, or rate, of the bicarbonate reaction?



In this chemistry science project, you will find out for yourself by plopping Alka-Seltzer tablets into water at different temperatures and measuring how long it takes for the chemical reaction to go to completion. In addition, you can record the sound of the Alka-Seltzer fizzle using a smartphone equipped with a sensor app. Do you think it will fizz more loudly in hot or cold water?



Terms and Concepts




Chemical reaction



Alka-Seltzer



Baking soda, or sodium bicarbonate



Molecule



Products



Temperature



Bicarbonate reaction



Reaction rate




Questions




What is the bicarbonate reaction? What are its products?



Keeping in mind that an increase in temperature reflects an increase in the average molecular motion, how do you think increasing temperature will affect the reaction rate?



What temperature change do you think would be required to increase, or decrease, the reaction time by a factor of two?



What other factors besides temperature can affect how well a chemical reaction takes place?




Materials and Equipment




Alka-Seltzer tablets (at least 12; if you plan to do additional variations to the project, you will want to get a larger box)



Thermometer with a range of at least 0C to 60C (32F to 140F)

A suitable thermometer is available from Amazon.com



A standard kitchen candy thermometer will also work fine





Clear drinking glasses or jars; about 8 ounces, or 240 milliliters (two of the same size)



Graduated cylinder, 100 mL. A 100 mL graduated cylinder is available from Amazon.com. Alternatively, measuring cups may be used.



Masking tape



Hot and cold tap water



Ice



With option 2 in procedure: Stopwatch or a clock or watch with a second hand



Optional: A helper



Lab notebook



Pencil



With option 1 in procedure: Smartphone with a sensor app such as phyphox, available for free on Google Play for Android devices (version 4.0 or newer) or from the App Store for iOS devices (iOS 9.0 or newer).



With option 1 in procedure: Small sealable (waterproof) plastic bag that fits your phone inside of it




ConditionTemperature(C)Reaction Time(s)Optional: Maximum Sound Intensity(dB)Trial #1Trial #2Trial #3AverageTrial #1Trial #2Trial #3AverageHot Tap Water         Cold Tap Water         Ice Water         Table 1. In your lab notebook, make a data table like this one. You will record your results in it.



Experimental Procedure



Note: In this science project, you will investigate how water temperature affects the dissolving time of an Alka-Seltzer tablet. You will use a smartphone equipped with a sensor app to record the fizzing sound of the Alka-Seltzer reaction in water and measure the time it takes for one Alka-Seltzer tablet to react completely in water. The app creates a graph that will not only give you information about the reaction time but will also allow you to assess how loud each reaction was based on the measured sound intensities. If you do not have a phone, you can observe the reaction and use a stopwatch to time how long it takes for each tablet to dissolve.



Figure 2. Mark your glass on the outside with masking tape to indicate a water level up to about 1 inch below the rim.M. Temming



Do your background research and make sure that you are familiar with the terms and concepts in the Background.



In your lab notebook, make a data table like Table 1. You will record your results in this data table.



Prepare a drinking glass so that it is marked at the 200 mL point. You will use the same glass for multiple trials, so it is convenient to mark the desired water level. Note: If your glass fits more than 8 ounces, make a mark about 1 inch below the rim.

Add 200 mL (a little less than 1 cup) of water to the drinking glass, or fill it up to about 1 inch below the rim.



Use a piece of masking tape on the outside of the glass to mark the water level, placing the tape with its top edge even with the water level in the glass, as shown in Figure 2.



Note: You do not want to fill the glass completely full because the bicarbonate reaction produces bubbles that could splash out.





You will fill the drinking glass with the same volume of water at three different temperatures: hot tap water, cold tap water and ice water.

For the hot and cold tap water, run the water until the temperature stabilizes. Fill the glass with water to the level of the masking tape. Be careful when handling the hot water.



For ice water, fill the glass about half full with ice cubes, then add cold tap water to a bit above the level of the masking tape. Stir for a minute or two so that the temperature equilibrates. Once temperature has equilibrated, remove the ice cubes from the water’s surface using a spoon or other utensil immediately before adding the Alka-Seltzer tablet. (Pour out any extra water so that the water is up to the level of the masking tape.)





Prepare the drinking glass with one of the three temperatures as described in step 4. Then measure the reaction time for that temperature either by following option 1 (sensor app), described in step 6, or option 2 (stopwatch), described in step 7.

If you use the phyphox app to measure the amplitude of sounds, you will need to calibrate the sensor first to get correct decibel readings on your device. The sensor has to be recalibrated between individual recordings. Instructions on how to do the phyphox sound sensor calibration are provided in the video above.



Option 1: Using the Sensor AppSensor apps such as phyphox let you record data using sensors that are built into many smartphones, including a microphone that you can use to measure sound. In this project, you can use the app to record the fizzing sound that the Alka-Seltzer tablet makes while it dissolves in water and then use the data to determine the reaction time and maximum sound intensity for each reaction.



Open the sensor app on your phone and select the sound sensor (audio amplitude in phyphox). Remember, that when you are using the phyphox app you will have to calibrate the audio amplitude sensor (sound sensor) before you do any measurements. Do this calibration before you start your investigation, so you get correct sound intensity readings. To calibrate your sound sensor in phyphox, follow the instructions in the sound sensor calibration video. You will have to re-calibrate the audio amplitude sensor (re-set the decibel offset) every time you start a new recording! Once you have calibrated the sensor, make sure you know where the microphone is located on your phone and do a quick test to see if your sound measurement is working. For example, you could record yourself clapping or singing to check if the sensor behaves as expected.



Once you have confirmed that the sensor works and you are familiar with the app, you can start with the experiment. You should do this experiment in a quiet environment. The background reading of your sound meter when there is no noise in the room should be in the range between 2040 decibels (dB).



Measure the temperature of the water (in Celsius [C]) in the first glass that you prepared, and record it in the data table in your lab notebook. Remove the thermometer from the glass before continuing with the next step.



Put your phone in the waterproof plastic bag and make sure it is sealed well. You don’t want it to get wet!



Place the second, same-sized glass, next to the glass filled with water. Lay your phone on top of the second glass so that the microphone (or sound sensor) is located right at the center above the glass filled with water, as shown in Figure 3.Figure 3. Place your phone on top of the glass filled with water so that the microphone (or sound sensor) is located right at the center above the solution.M. Temming





Take one whole Alka-Seltzer tablet out of its package and hold it above the glass filled with water. In the phyphox app, start a new recording for your first experiment by pressing the play button.



Once the recording starts, drop the tablet into the water. Note: You have to be very quiet during the experiment. Any sound that you make will be recorded and could affect your data. Try to be as quiet as possible while you are recording your data!



You will immediately see and hear bubbles of CO2 streaming out from the tablet.



The tablet will gradually disintegrate. Observe the graph recorded by the app, and how the sound sensor is responding to the fizzling while all of the solid white material from the tablet disappears.



When the solid material has completely disappeared, and you see on the graph that the sound intensity has reached background levels again or does not change anymore, wait 20 more seconds until all the bubbles have stopped forming, and stop recording your data. Make sure to save your data and label it appropriately such as “hot water,” “cold water” or “ice water.” Figure 4. This example data from the phyphox app demonstrates how to measure the reaction time of the Alka-Seltzer tablet dissolving. The x-axes of the graphs are time in seconds [s] and the y-axes shows sound intensity in decibels [dB].Made with phyphox by M. Temming





Your data should look something like the graph in Figure 4. Your graph should show an increased sound intensity for as long as the Alka-Seltzer reaction took place. The sound level of the reaction might be louder in the beginning and decrease as the tablet gets smaller. In the graph, every bubble that pops in the solution is represented by a spike.



Measure the time between the beginning of your reaction (when you dropped the tablet and the sound intensity started to increase) and the end of the reaction (when the sound intensity reached background levels again or does not change significantly anymore). In phyphox, you can use the pick data function to select the respective data points and view their time and decibel values. For example, the reaction in Figure 4 started a little after 3 seconds and ended at about 66 seconds.



Calculate the time difference between these two points. The result is the reaction time for your first trial. Record the reaction time (in seconds [s]) in the data table in your lab notebook.



Tip: Be careful when opening the packets and handling the Alka-Seltzer tablets. The tablets are thin and brittle, so they break easily. If some of the tablets are whole, and some are broken into many pieces, the separate trials will not be a fair test. You should only use whole tablets.





Option 2: Using the stopwatch

After filling the glass to the level of the masking tape, measure the temperature of the water (in Celsius [C]), and record it in the data table in your lab notebook.



Remove the thermometer from the glass before continuing with the next step.



Have your helper get ready with the stop watch, while you get ready with an Alka-Seltzer tablet. Have your helper count onetwothree. On three, the helper starts the stop watch and you drop the tablet into the water.



You will immediately see bubbles of CO2 streaming out from the tablet.



The tablet will gradually disintegrate. Watch for all of the solid white material from the tablet to disappear.



When the solid material has completely disappeared, and the bubbles have stopped forming, say “Stop!” to have your helper stop the stopwatch.



Record the reaction time (in seconds [s]) in the data table in your lab notebook.



Tip: Be careful when opening the packets and handling the Alka-Seltzer tablets. The tablets are thin and brittle, so they break easily. If some of the tablets are whole, and some are broken into many pieces, the separate trials will not be a fair test. You should only use whole tablets.





Repeat step 6 or 7 two more times with the same temperature of water. If you use the sensor app, make sure your sound sensor is still calibrated and recalibrate it again (re-set the decibel offset) if necessary before each recording.

Repeating an experiment helps ensure that your results are accurate and reproducible.





Repeat steps 5 and 6 or 5 and 7 for each of the other temperatures.

When you are done, you should have done a total of three trials for each of the three temperatures.





Calculate the average reaction time for each of the three water temperatures. Record your results in the data table in your lab notebook.



Make a graph of the average reaction time, in seconds (on the Y-axis), vs. water temperature, in degrees Celsius (on the X-axis).



How does reaction time change with temperature? Can you explain why this is?

Hint: If you are having trouble explaining your results, try re-reading the Introduction in the Background.





If you chose to use a sensor app to record your data, look at the graphs for each water temperature again. Write down the maximum sound intensity that you observed during the Alka-Seltzer reaction (not including the initial or end peaks) for each trial. You can get the number in the phyphox app by using the pick data tool to select the timepoint at which the sound intensity is highest. In the example shown in Figure 4, this would be around 35 seconds with a sound intensity of about 50 decibels. Calculate the average for each of the three water temperatures and record your results in the data table in your lab notebook.



Make a graph of the average maximum sound intensity, in decibels (on the Y-axis), vs. water temperature, in degree Celsius (on the X-axis).



Which reaction was the loudest? Did you expect these results?






Variations




More advanced students should also calculate the standard deviation of the reaction times for each temperature.

Use the standard deviation to add error bars to your graph.



For example, say that the average reaction time for one temperature was 45 seconds, and the standard deviation was 5.2 seconds (these are made-up numbers). You would graph the symbol for the data point at 45 seconds, and then draw short vertical bars above and below the symbol. Each vertical bar would have a length equivalent to 5.2 seconds.



Error bars give your audience a measure of the variance in your data.





Adult supervision required. Is reaction rate predictable over a larger temperature range? Water remains liquid above 0 C and below 100 C. Repeat the experiment at one or more additional high temperatures to find out. Use Pyrex glass for containing water heated on the stove or in the microwave, and use appropriate care (e.g., wear hot mitts and safety goggles) when handling hot water. A standard candy thermometer should be able to measure the temperatures in this higher range.



You could turn the bicarbonate reaction into a home-made lava lamp. To do this, you will want to use a tall jar or empty clear plastic 1-liter or 2-liter bottle, fill it with 2 to 5 centimeters (cm) of water, add 5 drops of food coloring, and then fill it at least three-quarters full with vegetable oil. You could repeat the science project using your homemade lava lamp at a cold and a hot temperature. To do this, you will need to figure out a way to make the prepared bottle hot or cold. (For example, to make it hot you could let it sit in a large bowl of hot water, and to make it cold you could store it in a refrigerator or freezer.) You will also want to use one-quarter of an Alka-Seltzer tablet at a time (instead of a whole tablet). How does the bicarbonate reaction look and function in the home-made lava lamp?




This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.

Butterflies and bees do it. Frogs and even salmon do it. What is it? Its metamorphosis.



The term describes a series of dramatic physical changes that an organism undergoes as it matures. The term comes from the Greek word for change of form.



Lets learn about amphibians



Lots of young animals look different from their parents. But metamorphosis is distinct from just growing up. Some animals emerge from metamorphosis with brand-new organs, such as wings or lungs. Others switch what types of food they eat or may wind up not eating at all! These differences may benefit animals by minimizing competition for resources between adults and babies of the same species.Insects, amphibians and certain fish are among the more well-known animals that metamorphose. But theyre not the only ones. Jellyfish, mollusks and sea stars have all been observed undergoing this real-life shapeshifting. Crabs, lobsters and other crustaceans have, too.





Body remodel



Many animals that metamorphose have babies that look entirely different from their adult forms. Think of a frog. Frogs have powerful back legs and lungs. But many frog species start life underwater as tadpoles. Unlike frogs, tadpoles rely on gills and long tails to maneuver underwater.



Jellyfish, meanwhile, start out as free-swimming young called larvae. These larvae attach to hard surfaces and transform into anemone-like polyps. These polyps spend much of their early lives using their tentacles to catch passing prey. Eventually, the tentacles begin to bud into free-floating jellies. They then detach from their home surface and hit the high seas.



Like jellyfish, sea urchins also start their lives as larvae swimming in the ocean. These larvae use long arms to snag phytoplankton to eat. During metamorphosis, a sea urchin grows adult limbs and organs from a cluster of cells inside its body called a rudiment. The urchins absorb their larval arms and mouths into their bodies. Then they drop to the seafloor as newly formed adults.



These spiky purple sea urchins started out life as free-swimming larvae before they underwent metamorphosis into their current forms.Brent Durand/Getty Images


Insect transformations



Metamorphosis is especially common in insects. But some insect transformations are more dramatic than others.



Take butterflies. A crawling, leaf-munching caterpillar can transition into a flying, nectar-sipping butterfly within a few weeks. This is an example of complete metamorphosis. During this type of metamorphosis, insects go through four life stages: egg, larva, pupa and adult. At each stage, the insect will look completely different.



Explainer: Insects, arachnids and other arthropods



The process begins with an egg laid by an adult. A small, soft-bodied larva, such as a caterpillar, hatches from this egg. Larvae do not have many of the organs found in adults. And they have one goal: eat as much as they can.A caterpillar doesn’t have wings, doesn’t have any reproductive organs, says Jens Rolff. It’s just like a big bag of tissues moving on a plant and feeding. Constantly feeding. Rolff is an evolutionary biologist who studies insects. He works at Freie Universitt in Berlin, Germany.Healthy appetites help a larva pack on fat. And that will fuel the development of its organs once the larva becomes a pupa. At the pupa stage, the larva stops eating and develops a protective covering. Caterpillars develop a hard, outer layer called a chrysalis.







When the larva pupates, the job is to generate a new animal, says Rolff. Inside the pupa, proteins called enzymes begin to break down the larvas tissues. These dissolved tissues are used to rebuild muscles and organs such as the brain and gut. Special groups of cells called imaginal discs become activated and help create wings, new mouthparts and reproductive organs. Once these changes are complete, an adult insect emerges.



That adult often moves and eats in totally different ways than it did as a pupa.



About eight in every 10 insect species undergo complete metamorphosis. Beetles, flies, bees, ants and fleas are just a few examples. Together, this group makes up about 60 percent of all animals on Earth. Complete metamorphosis has been around for a while, too. Fossils suggest that insects were doing it at least 250 million years ago, Rolff says.





Check out one of the worlds largest beetles going through metamorphosis in this video from Nat Geo WILD.



Not all insects go through this full process, though. Grasshoppers, cockroaches, cicadas and dragonflies go through a three-stage version known as incomplete metamorphosis.



Here, insects emerge from eggs as nymphs, which look much like miniature adults. They are just missing developed wings and sex organs. Nymph forms of these species gradually get larger by shedding their hard outer shell, or exoskeleton, through a process called molting. Wings and reproductive organs continue to develop with each molt. All insects grow by molting. But insects that undergo complete metamorphosis only do so while plumping themselves up as larvae. Nymphs will go through multiple molts until they reach adulthood.

On Jupiter, lightning jerks and jolts a lot like it does on Earth. 



New views of storms on Jupiter hint that its lightning bolts build by lurching forward. Whats more, those staggering steps happen at a similar pace to lightning bolts on our own planet. 



Arcs of lightning on both worlds seem to move like a winded hiker going up a mountain, says Ivana Kolmaov. A hiker might pause after each step to catch their breath. Likewise, lightning on Earth and Jupiter both seem to build by one step, another step, then another, Kolmaov says. Shes an atmospheric physicist at the Czech Academy of Sciences in Prague. Her team shared the new findings May 23 inNature Communications.  





The discovery about Jupiters lightning doesnt just offer new insights into this gas giant. It could also help aid in the search for alien life. After all, experiments hint that lightning on Earth could have forged some of the chemical ingredients for life. If lightning works a similar way on other worlds, it might produce lifes building blocks on distant planets, too. 



Lightning, step by step 



Here on Earth, winds within thunderclouds whip up lightning. The winds cause many ice crystals and water droplets to rub together. As a result, those tiny bits of ice and water become electrically charged. Bits with opposite charges move to opposite sides of the clouds, building up charge on either end.  



Lets learn about lightning



When that charge buildup gets big enough, electrons are released the lightning takes its first step. From there, the surging electrons repeatedly rip electrons off molecules in new segments of air and rush into those segments. So the bolt of lightning leaps forward at tens of thousands of meters per second, on average. 



Scientists thought Jupiters lightningmight also form by ice crystals and water droplets colliding. But no one knew whether the alien bolts grew step by step, as they do on Earth, or if they took some other form. 



Views from Juno 



Kolmaovs group looked at data from NASAs Juno spacecraft. Specifically, they looked at pulses of radio waves given off by Jupiters lightning. The data included hundreds of thousands of radio wave pulses from lightning over five years. 



Radio waves from each lightning bolt seemed to happen about once per millisecond. On Earth, lightning bolts that stretch from one part of a cloud to another pulse at about the same rate.This hints that Jupiters lightning builds in steps that are hundreds to thousands of meters long, too. 







Step-by-step lightning is not the only possible explanation for what Juno saw, says Richard Sonnenfeld. Hes an atmospheric physicist who wasnt involved in the study. He works at the New Mexico Institute of Mining and Technology in Socorro.   



The radio pulses could have come from electrons running back and forth along bolts of lightning, Sonnenfeld says. On Earth, such currents cause some bolts to appear to flicker. Still, he says, stop-and-go lightning formation is a perfectly reasonable explanation for the data. 

Its common to hear the term chaos used to describe seemingly random, unpredictable events. The energetic behavior of kids on a bus ride home from a field trip might be one example. But to scientists, chaos means something else. It refers to a system that is not totally random but still cannot be easily predicted. Theres a whole area of science devoted to this. Its known as chaos theory.



In a non-chaotic system, its easy to measure the details of the starting environment. A ball rolling down a hill is one example. Here, the balls mass and the hills height and angle of decline are the starting conditions. If you know these starting conditions, you can predict how fast and far the ball will roll.





A chaotic system is similarly sensitive to its initial conditions. But even tiny changes to those conditions can lead to huge changes later. So, its hard to look at a chaotic system at any given time and know exactly what its initial conditions were.



For example, have you ever wondered why predictions of the weather one to three days from now can be horribly wrong? Blame chaos. In fact, weather is the poster child of chaotic systems.





The origin of chaos theory



Mathematician Edward Lorenz developed modern chaos theory in the 1960s. At the time, he was a meteorologist at the Massachusetts Institute of Technology in Cambridge. His work involved using computers to predict weather patterns. That research turned up something strange. A computer could predict very different weather patterns from almost the same set of starting data.



But those starting data werent exactly the same. Small variations in the initial conditions led to wildly different outcomes.



To explain his findings, Lorenz likened the subtle differences in starting conditions to the impacts of the flapping wings of some distant butterfly. Indeed, by 1972 he called this the butterfly effect. The idea was that the flap of an insects wings in South America might set up conditions that led to a tornado in Texas. He suggested that even subtle air movements such as those caused by butterfly wings could create a domino effect. Over time and distance, those effects might add up and intensify winds.



Does a butterfly really affect the weather? Probably not. Bo-Wen Shen is a mathematician at San Diego State University in California. This idea is an oversimplification, he argues. In fact, the concept has been generalized mistakenly, Shen says. Its led to a belief that even small human actions could lead to huge unintended impacts. But the general idea that tiny changes to chaotic systems can have huge effects still holds up.





Maren Hunsberger, a scientist and actress, explains how chaos is not some random behavior, but instead describes things that are hard to predict well. This video shows why.



Studying chaos





Chaos is difficult to predict, but not impossible. From the outside, chaotic systems appear to have traits that are semi-random and unpredictable. But even though such systems are more sensitive to their initial conditions, they do still follow all the same laws of physics as simple systems. So the motions or events of even chaotic systems progress with almost clock-like precision. As such, they can be predictable and largely knowable if you can measure enough of those initial conditions.



One way scientists predict chaotic systems is by studying whats known as their strange attractors. A strange attractor is any underlying force that controls the overall behavior of a chaotic system.



Shaped like swirling ribbons, these attractors work somewhat like wind picking up leaves. Like leaves, chaotic systems are drawn to their attractors. Similarly, a rubber ducky in the ocean will be drawn to its attractor the ocean surface. This is true no matter how waves, winds and birds may jostle the toy. Knowing the shape and position of an attractor can help scientists predict the path of something (such as storm clouds) in a chaotic system.



Chaos theory can help scientists better understand many different processes besides weather and climate. For instance, it can help explain irregular heartbeats and the motions of star clusters.

Spacing out spaceflights may be better for astronauts brains.



Fluid-filled chambers in the human brain expand while in space. Its one way they adapt to lower gravity. But after a space mission, these structures dont shrink back right away. It might take three years to return to normal. Researchers reported this June 8 in Scientific Reports.



This suggests astronauts might need at least that long between flights before their brain is ready to be in space again.





With little gravity in space, fluids build up in an astronauts head. Sometimes their faces even look puffy when space travelers first arrive at the International Space Station, says Rachael Seidler. She studies how the human body adapts to space. She works at the University of Florida in Gainesville.



Extra fluid also collects in four chambers in the brain, called ventricles. Astronauts often return to Earth with enlarged ventricles. These chambers are filled with liquid that cushions the brain and clears out cellular wastes. In space, the ventricles expand as they take in more fluid, Seidler says.



She and her colleagues wanted to see how time spent in space affected the brain.





They examined MRI scans of the brains of 30 astronauts. Ones taken before each astronauts missions were compared to those taken after time in space. The longer the mission, the more that three of the four ventricles seemed to expand. (The fourth ventricle is very small, Seidler notes. So any changes in it may have been too tiny to see.)



Two-week spaceflights didnt have much effect. Both six- and 12-month missions, though, resulted in larger ventricles. The amount was similar after these longer trips, suggesting the swelling slows after six months in space.



Eighteen of the astronauts had flown in space before. The time since their last mission seemed to affect how much their brains changed during the new mission that the researchers were studying. In those whose last trip to space was three or more years earlier, three of their ventricles got bigger on average, by roughly 10 to 25 percent. Other astronauts had been to space less than three years prior. Their ventricles didnt swell much if at all. That suggests their brains may not have had enough time between missions to fully recover, the scientists say. 



Surviving Mars missions will take planning and lots of innovation



Im glad that the [study] authors took the first step and are looking at this question, says Donna Roberts. Shes a brain-imaging specialist at Medical University of South Carolina in Charleston. There are so many variables that could play into the brain changes that were seeing, Roberts says. Its hard to sort them out.



Spaceflights effects on the brain are even more pressing now, she notes. NASA aims to send people to Mars, which could be a two-year round trip. Everybody talks about the rocket technology to get to Mars, Roberts says. But the humans thats the real challenge.

For photosynthesis, one photon is all it takes.



Plants, algae and some bacteria perform photosynthesis. This chain of chemical reactions lets them transform sunlight into energy that they can use to grow. At the smallest scales, light is made up of particles called photons. Scientists long suspected that a single photon could spark photosynthesis. Until now, no one knew for sure.



The new experiment used a light source that produces just two photons at a time. One photon flew off to a detector. This particle signaled when the two photons had been released. The second photon went into a solution that contained light-absorbing structures from a bacterium. This species (Rhodobacter sphaeroides) can photosynthesize. It has light-harvesting structures called LH2. Each LH2 contains two rings of molecules.





Explainer: How photosynthesis works



In normal photosynthesis, LH2 absorbs a photon and then passes its energy to a series of other groups of molecules. Eventually the energy is turned into a form of chemical energy. That energy fuels the microbe.



But in the new experiment, there was nothing to hand that energy off to. So when LH2 absorbed the second photon shot out by the light source, it gave off a third photon. This photon had a different wavelength (light hue) than the one LH2 had absorbed. The new wavelength was a sign that energy had passed from the first ring of LH2 to the second. And thats step one of photosynthesis.



The researchers detected the photon given off by LH2. Then they compared the timing of its detection to when they detected the first photon spit out by their light source. This comparison confirmed the second photon had kicked off photosynthesis.



Researchers shared their findings June 14 in Nature.





Plants and bacteria do photosynthesis differently. In plants, multiple photons must be absorbed independently to complete photosynthesis. But the first steps in the process are similar enough that a single photon would set off photosynthesis in plants too, says Graham Fleming. This chemical physicist works at the University of California, Berkeley. He took part in the new research.



The role of single photons isnt surprising, says Richard Cogdell. Hes a biochemist who did not take part in the tests. He works in Scotland at the University of Glasgow. The important thing here, he says, is the technique that Flemings team used.



Many similar experiments have relied on light from lasers. But lasers shine much denser beams of photons than sunlight. In real life, photons rain down on the molecules that do photosynthesis in plants and bacteria at a much lower rate. Just a few tens of light particles with the right wavelengths hit these small areas each second.



Using only a single photon in the lab more closely mimics that real-world process. You can really work out whats happening in the early reactions in photosynthesis, says Cogdell. Its as if you could shrink yourself down and watch these photons moving around.

Tectonic plate (noun, Tek-TAHN-ick PLAYT)



Earths outermost layer, or lithosphere, is broken up into a giant jigsaw puzzle of tectonic plates. These huge slabs of rock hold both Earths continents and its seafloor. Theyre around 100 kilometers (miles) thick on average and include both Earths crust and upper mantle. Earth is covered in about a dozen main tectonic plates. And its the only planet known to have tectonic plates.



Explainer: Understanding plate tectonics



Earths tectonic plates continually slide around atop the hot, swirling rock beneath them. They move only a few centimeters per year. But over millions of years, those tiny movements add up. When tectonic plates bump into each other, they push up mountains. When plates slide beneath each other, they can form volcanoes. Plates can also slide past each other. Each of these movements can trigger earthquakes.



Even more dramatically, the shuffling of tectonic plates can give Earths surface a complete makeover. More than 200 million years ago, Earth had only one huge landmass: Pangaea. Over time, the shifting of tectonic plates broke that landmass apart and gave rise to the continents we see today.



In a sentence



A single catastrophic collision may have given Earth both its moon and its tectonic plates.



Check out the full list of Scientists Say.

Put a miniature poodle next to a wolf. The little poodle has a short, wiry coat. It has tiny, delicate paws. It has a puffy tail that sticks straight out or curls up. It is probably happy to play fetch, get snuggles or be dressed up in cute outfits, and to look to people for all its needs. The large wolf, in contrast, looks like a wild animal. It has a scruffy coat and fur that blends into its background. This doglike creature hunts with its pack and doesnt need or want anything to do with people.



These two animals arent so far apart biologically. They can even mate and produce puppies. But the biggest difference is that the ancestors of one of these animals the poodle became domesticated and developed a close relationship with humans.





Domestication is a process, says Sarah Crowley. She studies the relationship between humans and animals at the University of Exeter in England. And its a process that many familiar animals have undergone. These include dogs, of course, as well as cats, sheep, cattle, pigs and goats.





The process of domestication takes place over many animal and human generations. The animal may end up with changes in its genes, appearance and behavior. Its a relationship and process that affects us, too, Crowley notes. As people live closer and closer to those animals, human behaviors can adapt and change.



This is different from simply taming an animal, notes Greger Larson. Hes an evolutionary biologist at Oxford University in England. Monkeys taken captive as babies or tigers doing tricks on TV are tamed. But theyre not domesticated. A tamed animal is an animal that was an organism that was living in a wild context away from people, he says. When it was young, someone captured it and got it used to people. It is therefore less likely to eat you. It might still [eat you], but now it kind of knows you.



Domestication, on the other hand, is a long-term population shift, Larson explains. Consider two groups of sheep. One lives wild, while another hangs around people. Over time, the sheep living near people start to relax. The animals might rely on the people for food. The people also change their behavior with the sheep. The humans might pen the sheep, shear them or breed them instead of letting the sheep romance each other. Hundreds or thousands of years later, the wild sheep and now-domesticated sheep are completely different in both appearance and behavior.



A wild mouflon (left) doesnt look much like a fluffy white domesticated sheep (right). The two animals also behave very differently. But sheep were probably domesticated from mouflon more than 10,000 years ago in Mesopotamia, an area near present-day Iraq and Iran.Dave/iStock/Getty Images Plus; George Pachantouris/Getty Images


The question of domestication syndrome



Scientists have attempted to identify traits that all domesticated animals have. These would be traits that make domesticated animals different from wild ones. All together, these traits are often called domestication syndrome.



Decreased fearfulness and aggression are behaviors that are generally assumed to follow domestication, says Christina Hansen Wheat. We expect domesticated animals to be more social and playful. Hansen Wheat is a behavioral ecologist. She studies how animals interact with each other in an environment. She works at Stockholm University in Sweden.



With domestication syndrome, tame behaviors go along with physical changes, explains Hansen Wheat. Domesticated animals might have curly tails and floppy ears. They would be more likely to have white spots. They might also be able to breed when they are younger than their wild cousins. Some can breed all year round instead of having a breeding season. They might have smaller brains and bigger bodies.





At first glance, this seems to make sense. Domesticated dogs, pigs, sheep, horses and cows can all have floppy ears and often have white spots.



However, theres a problem. Scientists have made many guesses about why domestication syndrome might occur. But none have been shown to be true. This could be because when scientists look closer, domestication syndrome itself falls apart, says Larson. No domesticated animal has every single trait in the syndrome, he notes. Instead, domestication syndrome might be people trying to see common traits in the animals they are close to.



People live with their cats, live with their dogs, horses, cows and sheep and pigs. And so, everybody feels like they know what it is, he says. We are primed to see differences when those things matter to us.



Domestication syndrome, Larson says, is also based on the idea that humans intended to domesticate an animal in the first place. When we think about all the animals now that are very close to us, none of them were animals that any one person deliberately went out and said, I’m going to make this a domestic animal, he notes. No one grabbed the first sheep and put it in a barn until it behaved.



Instead, animal domestication is a growing relationship. Humans and another species get closer and closer. Eventually, they couldnt imagine a life apart. Its a relationship that affects us just as much as it affects the animals, Crowley says. And the relationship is always changing. Some animals might get closer to us, while others get released to run wild again, such as pigeons.



In the end, Larson says, the math to make a domestic animal is simple: an organism, plus people, plus time.

There are diapers in this house but not where you might think. Used diapers partly make up its floors, columns and walls.



A team of researchers tested used diapers as one ingredient in building material. To build a new house, the team mixed recycled disposable diapers into concrete and mortar. Mortar is used to hold bricks together.



The team designed a single-story home that covers about 36 square meters (388 square feet). Recycled diapers could replace nearly 2 cubic meters (71 cubic feet) of its building materials. These findings appeared May 18 in Scientific Reports.





Repurposing diapers to make building materials would shrink the amount of trash that goes to a landfill. It could also make homes more affordable, the team says. Thats a big need in developing countries such as the Southeast Asian nation of Indonesia. There, demand for low-cost housing outstrips whats available.



The number of people in Indonesias cities has climbed by about 4 percent per year in the last 30 years. And more people are moving to the countrys urban centers. By 2025, more than two-thirds of Indonesians are expected to live in urban areas, says Siswanti Zuraida. An environmental engineer, she works at the University of Kitakyushu in Japan. Zuraida is from Indonesia. All the waste people make is becoming a problem, she says. And Indonesias population boom is straining the demand for housing.



Building materials especially those that make for strong structures are often expensive. Theyre often the biggest barrier to making homes affordable. So researchers have previously investigated unusual materials that could save costs. These materials included many that would otherwise pile up as waste, such as the husks of rice grains or fly ash. Thats the fine particles left over from burning coal.



Maybe giving old diapers a new use could help tackle both problems. Used disposable diapers mostly pile up in landfills or get burned. But disposable diapers contain wood pulp, cotton and plastic. All of those are potentially useful building materials.





A diaper change



Mortar and concrete are typically made from sand, gravel and other materials. Zuraida and colleagues tried replacing some of those materials with used diapers. Then they tested their mixtures to see if structures built with them would be strong enough.



The diapers have to be cleaned up before being reused. The team washed, dried, sterilized and shredded diapers. Then they made six different samples of concrete and mortar. Each used differing amounts of diapers, cement, sand, gravel and water. Crushing the samples in a machine revealed how much weight each could bear. Adding more diaper material reduced the strength of the mixture, they found.



The team designed and built a small home based on the maximum amount of diaper waste they found they could use. Their one-story house had two bedrooms and one bathroom. Recycled diapers could replace up to 27 percent of the typical materials used in load-bearing structures. Those are the structures that help hold up a building, such as columns and beams.







Taller buildings cant use as much diaper material, the team found. A three-story home could use up to 10 percent disposable diapers in load-bearing structures. But other parts of homes dont have to support a lot of weight. Those include garden paving blocks and walls that divide rooms. There, shredded diapers could replace up to 40 percent of the sand.



But there are big hurdles to adopting diapers or other unusual building materials, Zuraida says.





Diapers plant-based fibers can be used for building. But their plastic parts would have to be separated out. That takes a complicated process that, for now, is available only in developed nations. And Indonesias laws restrict what materials can be used for construction. Right now, its just concrete, bricks, wood and ceramics. (Making such materials emits a lot of greenhouse gases.)



The idea of building with waste is worthwhile, says Christof Schrfl. A chemist, he works at Technische Universitt Dresden in Germany. Schrfl wasnt part of the new work. But reusing diapers might not be that environmentally friendly, he says, especially on a large scale. Its tricky to separate dirty diapers from waste and sanitize them. So it would take a lot of energy to recycle diapers.

Pulsar (noun, PUHL-sahr)



Pulsars are dense, quickly spinning cores of dead stars that blast radio waves into space.



When a star thats a few times as big as the sun dies, it shoots most of its mass off into space in a huge explosion. That explosion is called a supernova. But the core of the star collapses in on itself and forms an ultra-dense neutron star. All that mass clumps together under the force of gravity. That causes the dead star to spin faster, just like an ice skater pulling in their arms during a turn. Neutron stars can spin faster than the tires on a race car at top speed anywhere from once every few seconds to hundreds of times per second. Thats millions of times faster than the Sun spins.





A pulsar is a special kind of neutron star that blasts out two beams of radio waves in opposite directions. As the dead star spins, those beams sweep through space like the lights on a lighthouse. If Earth is in the path of one of those beams, we see a flash of radio waves every time it sweeps past us. That makes the pulsar appear to pulse at very regular intervals.



This animation shows a pulsars radio beams (purple) sweeping through space. When one of the beams passes over Earth, the pulsar appears to flash.



Astronomer Jocelyn Bell Burnell first discovered pulsars in 1967. At first, some scientists thought the radio beams she saw might be coming from aliens. That was because the pulses were so regular. But then Bell Burnell found radio pulses coming from a different part of space, far from the first signal. It was unlikely that two groups of aliens were signaling us at the same time from so far apart, so scientists looked for a different explanation. They eventually learned the radio waves were coming from pulsars scattered throughout space.



Scientists today use pulsars to make maps of space and keep time in the cosmos. Pulsars can also be used study the fundamental laws of physics that rule the universe.



In a sentence



Scientists time the radio flashes from pulsars to look for gravitational waves.



Check out the full list of Scientists Say.

Massive Otodus megalodon sharks the oceans largest meat-eaters ever ran hot. It now appears that their rise (and fall) may have been tied to their warm-bloodedness.



Chemical measurements on fossil O. megalodon teeth suggest the sharks had higher body temperatures than surrounding waters. Analyses of carbon and oxygen in the teeth revealed that the giant sharks body temperature was about 7 degrees Celsius (13 degrees Fahrenheit) warmer than seawater temperatures at the time.





Lets learn about sharks



That warm-bloodedness may have been a double-edged sword. The trait may have helped megalodons become swift, fearsome apex predators. Those are hunters at the top of the food chain. O. megalodon grew up to 20 meters (66 feet) long. That makes it one of Earths biggest carnivores ever. But the sharks voracious appetite also may have spelled the species doom.



A creatures metabolism is the set of chemical reactions needed to sustain life. Gigantic bodies require a lot of food to power their metabolisms, notes Robert Eagle. A marine biogeochemist, he studies the chemistry of ocean ecosystems. Massive sharks may have been particularly vulnerable to extinction when food became scarce, he says. Eagle was part of a team that studied fossils of O. megalodon and its living and extinct kin to learn about the animals metabolisms.



Game over for megalodons



Mammals can boost their metabolisms and maintain their body heat, even in colder environments. This trait is called endothermy or warm-bloodedness. Some families of fish, both living and extinct, can do something similar. They can keep some body parts warmer than the surrounding water. This is known as regional warm-bloodedness. Many modern sharks belonging to the group that includes great white sharks have this ability.



Jacking up the temperatures of some body parts is one way some sharks evolved to be giant, says Jack Cooper. A paleobiologist, he studies ancient life at Swansea University in Wales. He did not take part in the new study. Filter feeding offers another path to getting large, Cooper points out. Gentler giants, such as whale sharks, use this strategy when they gulp lots of water and eat the tiny creatures within.



Scientists have long thought megalodon was regionally warm-blooded, Eagle says. Estimates of this beasts body shape, swimming speeds and energy needs point to some warm-bloodedness. The shark also was known to hunt in both colder and warmer waters. That suggests it had some control over its body temperature.





The question, Eagle says, isnt really whether O. megalodon was warm-blooded. Its how warm-blooded. His team wondered how the megasharks internal temps compared to one of its major competitors: the great white shark.



O. megalodon evolved around 23 million years ago. It went extinct sometime between 3.5 million and 2.6 million years ago. Great white sharks emerged late in megalodons reign, roughly 3.5 million years ago. They competed for food with their massive cousins.





Some scientists suspect this competition helped drive O. megalodon to extinction, especially when food became scarcer. The climate changed during the Pliocene Epoch, which spanned 5.3 million to 2.6 million years ago. That led to a sharp drop in the numbers of marine mammals. They were a primary food source for both sharks.



But the great whites stuck around when O. megalodon died out, Eagle says. Being the much smaller of the two, they likely needed less food to maintain their metabolism.



Ancient temperature check



To study the ancient sharks body temperatures, the team turned to the only fossils left by these sharks: their teeth.



Fossilized teeth can say a lot about the bodies they came from. A tooths enamel contains isotopes, heavier and lighter forms of a chemical element. Eagles team examined chemically bonded forms of heavier-than-usual carbon and oxygen. The technique acted as a kind of ancient thermometer. The abundance of bonds between these isotopes is only affected by body temperature, Eagle says.



Explainer: What are chemical bonds?



The team used this technique on teeth from great whites and megalodons. They also used it on other animals who lived at the same time. Mollusks are entirely cold-blooded; they cant control their body temperature. Analyzing ancient mollusks revealed the oceans water temperature.



Great whites and megalodons were at least somewhat warm-blooded, the team found. A megalodons body was warmer than the water around it. It also was warmer than the bodies of great white sharks. Neither shark, however, was as warm-blooded as marine mammals, such as whales.



The researchers shared their findings June 26 in Proceedings of the National Academy of Sciences.



It’s fantastic that we have more evidence for regional warm-bloodedness in megalodon, Cooper says. O. megalodons higher body temperature would have allowed it to swim further and faster, he says. That increased its chances of finding prey. But when the sharks prey dwindled some 3 million years ago, he says, megalodon may well have starved into extinction.



Eagles team is now exploring the chicken-or-egg question of which came first for megalodons: warm-bloodedness or apex-predator status. You need to be big to be a mega-predator. But its not clear whether carnivores need to be warm-blooded to become apex predators. Were hoping to fit it all together into an evolutionary story as to what drives what.

Predator and Prey, (nouns, PREH-duh-tor and PRAY)



The words predator and prey describe the roles in a relationship between two species. In this relationship, one species eats the other. The predator is the species that does the eating. The prey is the one that gets eaten. Predator/prey relationships are important links in food webs. These links move energy and nutrients through an ecosystem.



A bear fishing salmon from a river is one example of a predator/prey relationship. The bear is the predator. The salmon is the prey. But salmon must eat too. They snack on plankton, insects and other small critters. So in those cases, the salmon plays the role of predator.





Animals arent the only predators and prey. A rabbit chomping on grass is a predator, while the grass is its prey. But plants can also play the role of the predator. For example, a Venus flytrap (Dionaea muscipula) snares flies in its leafy jaws and digests them.



Predators and prey drive each others evolution. Over time, predators adapt to better catch prey. For example, the cheetahs powerful body can out-race its impala prey. But prey have evolved ways to avoid being eaten. The nimble impala can make a hard swerve that leaves behind the cheetah. Many plants have toxins, spines or other defenses that make eating them unpleasant. And millions of years ago, the need to escape marine predators likely helped drive some species from water to land.



In a sentence



Thanks to its predator/prey relationship with ants, the Australian ant-slayer spider (Euryopis umbilicata) evolved a cool somersault technique for capturing prey.



Check out the full list of Scientists Say.

Ghostly particles from space are giving us a new view of our galaxy.



Known as neutrinos, these subatomic particles have little mass and no electric charge. Theyre sometimes called ghost particles. Thats because they easily pass without a trace through gas, dust and even stars. High-energy neutrinos zip everywhere throughout the cosmos, carrying information about distant places. But where the particles come from has typically been a mystery.



Lets learn about ghost particles



Now, researchers found the first signs of high-energy neutrinos coming from within our Milky Way. They mapped the particles to create a new image of our galaxy. Its the first made with something other than light.





The map also hints at possible sources for these high-energy neutrinos. They could be the remains of past supernovas star explosions. Or they might come from the cores of collapsed supergiant stars or other unidentified objects. More research is needed to figure out the sources for all these neutrinos.



The new map of our galaxy was unveiled June 30 in Science.



Previously, only a few high-energy neutrinos have been traced back to their potential birth. They all came from outside the Milky Way. Two appeared to come from black holes shredding their companion stars. Others came from a type of galaxy called a blazar.



Explainer: Stars and their families



Its clear now that researchers are spotting neutrinos from both inside and outside our galaxy, says Kate Scholberg. Shes a physicist at Duke University in Durham, N.C., who did not take part in the new mapping project. Theres so much more to learn, she says. It can be tremendous fun to figure out how to see the universe with neutrino eyes.



Those neutrino eyes might one day allow us to see distant objects in a way that no other telescopes can match.



Some telescopes rely on visible light. Others pick up X-rays, gamma rays or the charged particles that make up cosmic rays. All of those types of light can be deflected or absorbed as they travel through space. Neutrinos, though, can cross huge expanses without being deflected. This allows the particles to tell us about very distant objects.




Three ways to map the Milky Way



Here are views of the Milky Way in visible light (top), gamma rays (middle) and high-energy neutrinos (bottom). Dust obscures portions of the visible-light map, and a variety of sources can generate gamma rays. Neutrinos have the potential to pinpoint remnants of supernovas, cores of collapsed stellar giants and other cosmic features.


IceCube Collaboration/Science 2023IceCube Collaboration/Science 2023





New look at old data



The ability of neutrinos to pass through things so easily also makes them extremely hard to detect. Scientists found the Milky Way particles using a neutrino detector in Antarctica. Called IceCube, this detector is embedded deep in the ice. To better detect ghostly neutrinos, its enormous. Its 5,160 sensors are arranged in a cube one kilometer (3,281 feet) on each side.



Even so, the experiment sees only a tiny share of the neutrinos that zip through space. IceCube scientists observe 100,000 or so neutrinos a year. Some of these neutrinos leave tracks in the detector. The scientists can sometimes trace these tracks back to the neutrinos source. Most of the neutrino signals that IceCube picks up, though, are a type called a cascade event. These leave bursts of light in the detector, but do not reveal a neutrinos origins as well as tracks can.



Astronomers used to throw away data on cascade events, says Naoko Kurahashi Neilson. Shes a physicist at Drexel University in Philadelphia, Pa. Those data can hold useful information about where the neutrinos come from. Its just hard to pick out which of those tens of thousands of cascade events are most important.





Kurahashi Neilson and her team took up the challenge. They dug through a decade of IceCube cascade-event data. They enlisted the help of an artificial-intelligence system known as a neural network. You can train the neural nets to identify which events are worth keeping, Kurahashi Neilson explains.



She pioneered this approach in 2017. Over the years, Kurahashi Neilson has steadily improved it. She and her colleagues have now used it to identify the neutrinos used to make the new map.



Its an impressive analysis, Scholberg says. And the technique may have the potential to be developed even more. Clearly a lot more work needs to be done, she says. But its very exciting to see the basic expectation [of Milky Way neutrinos] verified.

In 2022, an underwater volcano in the South Pacific island nation of Tonga made history. It spewed a plume of ash and water high enough to touch space. It also launched a tsunami as tall as the Statue of Liberty. Now, scientists find that it triggered lightning at the highest altitudes ever seen.



The eruption plume sparked lightning flashes that began 20 to 30 kilometers (about 12 to 19 miles) above sea level. Thats all the way up in the stratosphere even higher than most airplanes fly.





Researchers shared these findings on June 28. The work appeared in Geophysical Research Letters.



Lets learn about lightning



Lightning is most often born inside storm clouds. But lightning can also form inside a volcanos eruption plume. That plume is made of tiny bits of ash, gas and dust. When these tiny bits bump into each other, they make static electricity. Once enough static electricity builds up, lightning zips through the plume.



Alexa Van Eaton led a team that looked at how high the Tonga eruptions lightning was. Shes a volcano scientist at the U.S. Geological Surveys Cascades Volcano Observatory. Thats in Vancouver, Wash.



To estimate the lightnings height, Van Eatons team looked at a few different types of data. One was radio waves created by the lightning. They also examined satellite images of the eruption plume and infrared light from the flashes.



These data revealed the lightning started more than 20 kilometers (12 miles) above sea level. Lightning doesnt typically start that high. Air pressure at that height is usually too low to form lightning leaders. These are the channels of hot plasma that make up the lightning in thunderstorms.



Explainer: The volcano basics



The rising eruption plume may have increased the air pressure over the volcano, says Van Eaton. That might have been enough to create lightning leaders at strangely high altitudes.



In those eruption data, were seeing stuff that weve never seen before, says Jeff Lapierre. Hes a coauthor on the study. Hes also the principal lightning scientist at the Advanced Environmental Monitoring. Its a company based in Germantown, Md.



This eruption has completely changed the way we think of how natural events can change the atmosphere, Lapierre says. Its also changed the environment where we thought lightning could exist.

Northern elephant seals are the true masters of the power nap.



These marine mammals swim at sea for months between brief breaks on shore. During those sea voyages, the seals snooze less than 20 minutes at a time. On average, they get a total of just two hours of shut-eye per day.



This extreme sleep schedule rivals African elephants for the least sleep seen among mammals.



Researchers shared the discovery in the April 21 Science.



Its important to map these extremes of [sleep behavior] across the animal kingdom, says Jessica Kendall-Bar. She studies marine mammals at the University of California, San Diego. Learning how much or how little sleep different animals get could help reveal why animals, including people, sleep at all.





Knowing how seals catch their zzzs also could guide efforts to protect places where they sleep.





Tracking seal sleep



Northern elephant seals (Mirounga angustirostris) spend most of the year in the Pacific Ocean. At sea, those animals hunt around the clock for fish, squid and other food.



The elephant seals, in turn, are hunted by sharks and killer whales. The seals are most vulnerable to such predators at the sea surface. So they come up for air only a couple minutes at a time between 10- to 30-minute dives.



People had known that these seals dive almost all the time when theyre out in the ocean. But it wasnt known if and how they sleep, notes Niels Rattenborg. He wasnt involved in the new study, but he has studied animal sleep. He works in Seewiesen, Germany, at the Max Planck Institute for Biological Intelligence.



Explainer: How to read brain activity



Kendall-Bars team wanted to find out if northern elephant seals really do sleep while diving. To do this, the researchers outfitted two northern elephant seals with special caps. Those caps recorded the animals brain waves, revealing when they were asleep. Motion sensors were also strapped onto the seals.



By looking at both brain-wave readings and motion data, the researchers could see how seals moved while asleep.



Kendall-Bars team took their two seals from Ao Nuevo State Park. Thats on the coast of California, north of Santa Cruz. The researchers then released the seals at another beach, one about 60 kilometers (37 miles) south of Ao Nuevo. To swim home, the seals had to cross the deep Monterey Canyon. The waters here are similar to those in the deep Pacific, where the seals swim during their months-long trips at sea.





Matching the seals brain-wave readings to their diving motions on this journey showed how northern elephant seals get their sleep on long voyages.



Deep-sea snoozes



The data revealed that when a northern elephant seal wants to sleep at sea, it first dives 60 to 100 meters (200 to 360 feet) below the surface. Then, it relaxes into a glide. As the seal nods off, it keeps holding itself upright for several minutes.



But then, the seal slips into a stage of rest known as REM sleep. During this sleep stage, the animals body becomes paralyzed. A slumbering seal now flips upside-down and drifts in a gentle spiral toward the seafloor.



A northern elephant seal can descend hundreds of meters (yards) deep during one of these naps. Thats far below the waters where sharks and killer whales normally prowl. When a seal wakes after a five- to 10-minute nap, it swims back to the surface. The whole routine takes about 20 minutes.



Explainer: Tagging through history



Now that Kendall-Bars team knew how seals moved during sleep, they could pick out naps in motion data from other seals who hadnt been outfitted with the special caps.



The researchers looked for naptime dive motions in tracking data on 334 other northern elephant seals. Those seals had been outfitted with tracking tags from 2004 to 2019. The seals movements revealed that while at sea these creatures conk out, on average, only around two hours per day.



But northern elephant seals arent short on sleep all the time. They snooze nearly 11 hours per day when they come on land to mate and molt. On the beach, they can catch up on sleep without worrying about getting eaten.



What the seals are doing [at the beach] might be something like what we do when we sleep in on the weekend, Rattenborg says.



Northern elephant seal naps are no joke. While on land, these animals can conk out for a solid 11 hours per day. But at sea, the seals catch only brief bits of sleep.Photo by Jessica Kendall-Bar, NMFS 23188



Extreme animal sleep



Northern elephant seals arent the only animals that sleep very little, at times, and then a whole lot. Rattenborgs group has found a similar sleep pattern in great frigate birds. They fly over the ocean. They can sleep while theyre flying, Rattenborg says. So on those trips, they sleep less than an hour a day for up to a week at a time, he says. Once back on land, they sleep over 12 hours a day.



Curiously, the sleep habits of northern elephant seals seem quite different from those of other marine mammals. When studied in the lab, many marine mammals sleep with just half their brain at a time. That half-awake state allows dolphins, fur seals and sea lions to constantly watch for predators. They literally sleep with one eye open.



Its pretty cool that elephant seals get by without one-sided sleep, Kendall-Bar says. Theyre shutting off both halves of their brain completely and leaving themselves vulnerable. Diving far below predators is what allows the seals to rest easy.



It seems the key to their enjoying such deep sleep is sleeping deep in the sea.