The joy of living

© Stan Lupo, CC BY-NC-ND 2.0.

 

In the following extract from D.H. Lawrence’s “Fish”, he imagines the exuberance of a fish’s life:

Quelle joie de vivre [What a joy to live]

Dans l’eau! [In the water!]

Slowly to gape through the waters.

Alone with the element;

To sink, and rise, and go to sleep with the waters;

To speak endless inaudible wavelets into the wave;

To breathe from the flood at the gills,

Fish-blood slowly running next to the flood, extracting fish-fire;

To have the element under one, like a lover;

And to spring away with a curvetting click in the air,

Provocative.

Dropping back with a slap on the face of the flood.

And merging oneself!

To be a fish!

Do you think fish can experience the joy of living? That they could be happy or sad? There is some evidence that they can. Even though there are differences between our brains and theirs, overall there are quite a few physical similarities between us and fish. Even more so than between us and fruit flies, which scientists often use to study medical problems.

Jonathan Balcombe writes in his book What a Fish Knows:

I believe that the main source of our prejudices against fishes is their failure to show expressions that we associate with having feelings. “Fish are always in another element, silent and unsmiling, legless and dead-eyed,” writes Jonathan Safran Foer in Eating Animals. In those flat, glassy eyes we struggle to see anything more than a vacant stare. We hear no screams and see no tears when their mouths are impaled and their bodies pulled from the water. Their unblinking eyes—constantly bathed in water and thus in no need of lids—amplify the illusion that they feel nothing. With a deficit of stimuli that normally trigger our sympathy, we are thus numbed to the fish’s plight.

There is something to this. Scientists have shown that mice express their emotions on their faces, though we don’t usually notice it because we aren’t looking close enough...and they lack eyelids, so what we do notice are their beady little unblinking eyes, but as mammals we are able to recognize more similarities to us than we see with fish. Yet, we are a lot more like fish than you’d think.

For over the 100 millennia or so our ancestors were fish. That was approximately 518 million to 417 million years ago. The first fish resembled a swimming worm that was vertically flattened. The last of our fish ancestors, evolutionary biologist Richard Dawkins calculated, would be our 185-millionth great-grandparents. Twenty million years later, another group of our ancestors, tetrapods, that looked like a cross between a fish and a crocodile, began moving onto land.

During the period fish were our ancestors, they evolved many of the features that we still have today, prompting science writer Natalie Angier write, “everything we can do, fish can do wetter”. While that’s not entirely accurate, as she points out, they did evolve bones, vertebra, spinal cords, skulls, jaws, teeth, tongues, many of our internal organs, arms, legs, wrists and ankles that rotate, and they even gave us opposable thumbs. They also may have given us the ability of internal fertilization, internal pregnancies, and live births.

Fish can also do many things we don’t normally give them credit for. Some can breathe air, walk on land, and climb trees. Others can glide through the air. They stake out territories and defend them from intruders. They keep their homes clean. They have personalities that evolve over time based on their experiences. Some have complex social systems and hierarchies. They can be cooperative and establish reciprocal relationships. Some provide parental care and raise their young. Some have helpers who assist them with this.

You may be sarcastically thinking, “Yeah, right.” We’ll cover some of these later on, but let’s quickly take a quick look at some here.

Joy is a feeling, an emotion. Some consider it to be one of five basic emotions. They arise from hormones that are regulated by the brain’s limbic system and the neuroendocrine system, as determined by external cues, which in this case would be something that generates joy, such as play or chocolate.

Usually evolution doesn’t suddenly give rise to complex systems. It tinkers with and repurposes what is already there. As a result, our neuroendocrine system is very similar that in other mammals and in bony fish, while the limbic system is one of the most ancient parts of our brain. Physiologically, fish have the capacity to feel emotions, but whether they actually do is difficult to confirm.

We know that fish can suffer from depression and the neurochemistry of that is so similar to ours that zebrafish are now being used to develop new treatments for it. Fish that show the signs of depression recover when the antidepressants fluoxetine and diazepam—also known as Prozac and Valium, respectively—are added to their water.

For a number of reasons, zebrafish, like fruit files, are also used in medical research, including for studying arthritis. Fish do get arthritis. And you know how new mothers get “mommy brain” where their behavior and cognitive functions change? Well, small fish called sticklebacks get that too, except that in their case, it’s the males that get it, since they’re the ones who care for their young by circulating water around the eggs, keeping the nest clean, warding off predators, and retrieving stray fry, while the mother goes off to do her own thing.

Zebrafish are also used to study addiction. When given the choice, the fish will repeatedly dose themselves with the opioid hydrocodone, which is usually prescribed to treat pain, and they’ll even enter risky situations to get it. They also show signs of addiction, and withdrawal when going cold turkey. When given naloxone, a drug that counters the effects of opioids, the fish reduced their requests for hydrocodone. This isn’t surprising since they have the same receptor and neurotransmitters as we do for our reward system.

Like us, rats like to play and when they do, their brains release natural opiates and dopamine, a neurotransmitter and hormone that is involved in emotions, mood, motivation, movement, learning, and the reward system, among other things. It’s often called the “feel-good neurotransmitter”. All mammals have dopamine systems, and so do fish. Goldfish actively seek out amphetamines, which cause their brains to release dopamine, and they avoid pentobarbital, which inhibits its release.

In humans, dopamine suppression is associated with depression, stress, anxiety, low motivation, inability to concentrate, feeling hopeless, and being tired, but having difficulty sleeping. Some of these symptoms are detected in mice, fruit flies, and fish, making them good models for studying depression and other chronic ailments.

The New York Times article “Fish Depression Is Not a Joke” quotes biology professor and researcher Julian Pittman, with Troy University in Alabama saying, “The neurochemistry [in us and fish] is so similar that it’s scary”. That same article quotes other researchers who say the leading cause of depression in fish is probably boredom, since they are so naturally curious and crave novelty.

© Elaine Molina Stephens, 2024.

 

If you like this, please subscribe below to receive an email the next time I post something wondrous. It's free.

 

What’s happening to my head?

A flatfish with a sea star. John Butler, NOAA.

As with jellies, fish go through some major transformations. Often their juvenile form looks little like the adults, with some being wrongly classified as separate species. Some sport long appendages, such as the juvenile barbeled dragonfish whose guts exit its belly and trail behind, being as long or longer than its body.

In one of the most amazing examples of adaptation, flatfish have rearranged their bodies to adapt to life on the seafloor. While most animals are symmetric, flatfish are an exception. This includes flounders, sole, plaice, dabs, tonguefish, turbot, and halibut.

In the evolutionary scheme of things, they evolved rapidly over a three million year period, starting about sixty-five million years ago. They are born looking like regular fish, but as they mature they deform with one eye moving to the other side of their head and one side of their mouth rising up on their face so that its crooked. They end up looking like something out of a Picasso painting. Then they start swimming sideways.

These changes didn’t happen one at a time, but were coordinated through related genes. The eye didn’t move and then the mouth—the entire skull changed. This prompted further coordinated changes, such as their body flattening and their fins extending to run down the sides of their body. Their new bottom side—which can be either left or right depending on the species—remains white, while the upper side becomes pigmented for camouflage.

The fish are able to expand and contract the different-colored pigment cells in their skin, so are able to rapidly change their color and shading from light to dark to match their surroundings, confuse predators, and probably to communicate. Tropical flatfish can do this in a couple of seconds, while it can take a couple of days for a cold-water flatfish to change its camouflage. They are very good at this. When placed on a checkerboard, they do a pretty good job of matching the pattern. Well enough so that at a distance in a natural environment, they would blend in.

But fish that evolved to be flat bottom dwellers don’t all do it this way. Some, like rays and skates, flatten vertically without losing their symmetry. Still, these transformations are not nearly as drastic as caterpillars changing into butterflies, but they are striking for a non-insect.

This reformation happens during a stage of rapid growth—somewhat like our pre-teen years—when they suddenly begin leaning to one side when swimming. Then one of its eyes moves up the side of its head and over the top. Or it moves through its head to the other side. In some species this takes five days, in others just one day. And their behavior changes too, from swimming freely to a sedentary life on the bottom.

Some of these fish are large. The European plaice gets up to three feet in length (1 m). They spend their days hiding, buried in the sand, coming out at night to hunt for crustaceans and shellfish that they take into their mouths whole, crushing them with teeth in their throats. Some flatfish even eat lobsters and sand dollars, which don’t have much flesh in them.

Having both eyes on the same side of their head probably gives them 360-degree vision and might give them good depth perception where the visual fields overlap, but since their eyes swivel independently their brains probably process the input from each eye separately.

 

If you like this, please subscribe below to receive an email the next time I post something wondrous. It's free.

 

Attack of the bobbit worm

 

The bobbit worm's pincers are horizontal below its antennae. Jenny Huang, CC by 2.0 (adjusted).

One of the creepiest denizens of the seabed is the bobbit worm, named after the somewhat infamous couple, who—after the husband mistreated his wife—she taught him a rather severe lesson, and by her actions coined the word “Bobbittize”. This just adds to the horror of this worm’s terrifying appearance.

This bristle worm digs a tunnel down into the sand that’s long enough to comfortably fit its body with its hard exoskeleton, which can get up to nearly ten-feet (3 m) in length, although most are about three-feet long (1 m), with a diameter of one inch (2.5 cm).

They have two eyes, but are practically blind, so it uses its five antennae to sense its surroundings. During the day, with just its antennae and two pairs of pincers—retractable mandibles—poking out of its burrow, it waits for an unsuspecting fish, shrimp, snail, sea star, or worm to cruise by, or anything else edible that’s the appropriate size. The antennae move like worms, attracting prey. At night it extends a bit of its body out of the burrow and actively hunts.

When the prey gets close enough, with lightning-fast speed it extends up like a jack-in-the-box and seizes its prey with its sharp pincers, sometimes so strongly that it cuts its victim in half. When the prey remains intact, it injects venom through its teeth that stuns the prey, preventing it from struggling. Then it drags the victim down into its mucus-coated L-shaped burrow. Still, the victim can struggle enough to collapse the burrow’s entrance.

But in spite of all this, these worms aren’t carnivores—they’re omnivores—and they can live on seaweed, or algae and detritus they filter out of the water, or they will scavenge. If they feel threatened, they split themselves into a number of segments, each of which can regrow into a full worm. This is also one of the ways they reproduce, so they don’t mind.

When one of a shoal of fish, such as a bream, spots the worm’s antennae or if one is attacked, it swims vertically above the worm and spits streams of water at it, making the worm retract. Other fish—sometimes including fish of different species—may also join in, firing jets of water at the burrow. This makes them aware of the worm’s location, and might mark the burrow as a danger spot. It’s usually the juvenile breams that do this, not the adults, as they’re a bit more solitary, so it might be an educational lesson for the young.

Such mobbing behavior where prey team up to launch a coordinated attack against a predator is usually seen in birds, but also in some bovines, meerkats, ground squirrels, bees, ants, and freshwater bream called bluegills, which mob turtles, partly to drive them away from their nesting colonies. Humpback whales also mob orcas.

 

If you like this, please subscribe below to receive an email the next time I post something wondrous. It's free.

 

Megalodon

We’re not sure how big megalodons were, but this gives you a general idea. Compare it to the more accurate estimates below. Dinosaur Zoo, CC BY-SA 3.0.

The biggest known shark, and fish of any kind, was megalodon. We don’t really know how big it was since so far paleontologists have only teeth and a few vertebrae. It had cartilage instead of bone, and that doesn’t preserve well.

One estimate suggests it was plump and stalky, similar to great white sharks, and could get from fifty to sixty-five feet long (15 to 20 m). At the upper end, it would be roughly as long as a six-story building is high, or longer than an 18-wheeler tractor-trailer truck. Just think about that the next time you pass one on the highway. Imagine that it’s a megalodon swimming beside you, eyeing you with delight at having found a little snack.

Another estimate suggested it may have been longer and thinner, more like a mako shark, which would mean it was slower, less maneuverable, and unable to accelerate as quickly. While the second study refrained from giving an estimated size, one of its authors and their illustration indicated a range from fifty-five to seventy-nine feet (16.5 to 24 m).

It’s thought they weighed around fifty-five tons (50 tonnes)—roughly equal to eighteen large elephants, or about twenty-five great white sharks. And a man could stand on one’s back and would be about as tall as its dorsal fin. It was quite a large shark.

Megalodon means “big tooth” and its teeth were certainly big—about the size of a man’s stretched-open hand. It had five rows of very large teeth—276 of them, most of which were replacements for those that broke off.

Some evidence indicates that they were partly warm-blooded—meaning they kept their body temperature higher than the water they swam in—just as great white sharks, mako sharks, and a number of other sharks do today, but not quite the way we do. Because of their size, they probably had an even higher body temperature than those sharks. This would have made them more active and able to swim faster and for longer distances, but it also would have required them to burn through more food.

Megalodons were swimming around for about twenty million years, which is pretty good considering our species has only been around for about 315 thousand years. They first appeared around 23 million years ago—about 23 million years after the dinosaurs went extinct—and they disappeared 3.6 million years ago. There is no evidence of any megalodons existing since then. If they had, there would definitely be signs of their existence. They were gigantic apex predators that required a huge amount of food to survive.

Now, these are jaws.

Their primary prey were whales, seals, large fish, turtles, and other sharks. They could have eaten an orca in about five bites with their huge mouths, the largest being eleven feet wide by nine feet high (3.4 by 2.7 m). Scientists estimate its stomach could hold a twenty-six-foot-long (8 m), 6.6-ton (6 tonnes) orca. A meal like that could last it for two weeks, but they probably didn’t eat a complete whale.

It looks like they enjoyed eating just the faces of sperm whales—as do mako and great whites—leaving the rest behind for other creatures to eat. Sperm whale noses contain a lot of fat and oils, which sharks used to love devouring. Modern sharks no longer kill sperm whales, but orcas do.

Most whales were smaller back then, although by around seven million years ago the largest sperm whales did get up to the same size as a megalodon, but after megalodons went extinct, whales were free from their primary predator. As a result, they were able to grow in size to become the largest animals on earth. Blue whales evolved after the megalodon’s demise.

It’s not possible for one to still be hiding somewhere. While there are some areas of the ocean that aren’t frequently explored, such as the Mariana Trench, there’s not enough food in the deep ocean to feed such a huge animal, so it would have to live closer to the surface, and there would be some traces if something was killing that many whales. While we do continually discover new creatures in the ocean, nothing is anywhere near megalodon’s size. If they were still around, they probably would have evolved into something much smaller, but so far there’s no evidence of that either.

Several things could have caused megalodons to die out. At that time the earth was getting colder and that could have greatly reduced their food supply. Also there was a large drop in sea level from 5.3 million to 2.6 million years ago. This shrank their coastal habitat, reducing both their prey and their living space. Scientists suspect they may also have suffered from competition with great white sharks, which had appeared on the scene by that time. Sea levels today are even lower than they were then, although they are now rapidly rising again.

There may have also been changes at the locations where megalodons raised their young. So far researchers have found four of these nurseries covering different periods of time. They’re in Spain, Panama, Chesapeake Bay, and Florida. Most of these are now inland. They indicate megalodons devoted time to caring for their young, which weren’t fully grown until the age of twenty-five.

Now, you may be surprised to learn that a toothed whale grew to be just as large as megalodon. A fossil of one was found from twelve million years ago, right in the middle of megalodon’s reign and at fifty-five feet (17 m), it was about the same size. And, being a toothed whale, it had teeth, perhaps for fighting off or eating megalodons. It’s called leviathan and is thought to have looked like a sperm whale, but where sperm whales only have teeth in their lower jaws, leviathan had teeth twice the size in its upper and lower jaws, and unlike sharks, whose teeth are embedded in their gums, leviathan’s teeth were embedded in bone.

 

If you like this, please subscribe below to receive an email the next time I post something wondrous. It's free.

The Fastest Thing in the Universe (What is Real? 27)

These posts make more sense when read in order.

Please click here for the first article in this series to enter the rabbit hole.

 

© KarstenLoewenstein, CC-BY-3.0 & GFDL.

Einstein’s interest in electromagnetism centered on the work of James Clerk Maxwell. In the 1860s Maxwell had come up with the unified theory of electromagnetism by combining magnetism with electricity. One feature of Maxwell’s equations was that they didn’t make sense unless light traveled at a set rate, no matter how fast the light’s source was moving.

Einstein took the constant speed of light and raised it to the level of a law of nature. While pondering the implications of this, Einstein realized that nothing can go faster than the speed of light, which in a vacuum is approximately 671 million miles per hour (1.08 trillion km/h).

Here’s where it starts to get counterintuitive. Since the speed of light remains the same in all frames of reference, if you had a rocket with a headlight and it was traveling at half the speed of light and you turned that light on, you would think that the photons shining from the light would zip away at one and a half times the speed of light, but it doesn’t work that way. Light in a vacuum always travels at the speed of light. That’s its maximum and minimum speed. If you release some photons in a vacuum, they will shoot off as fast as they can, or as slow as they can, depending on how you look at it. Either way, it’s the same thing since light always goes at one speed.

If two remotely controlled racecars collide head on and each are going 100 mph (161 km/h), then the speed of the collusion will be 200 mph (322 km/h)—the vehicles’ speeds combined—but if two beams of light meet—they can’t collide and will pass right through each other because they have no mass—their meeting will be at the speed of light, not the speeds combined. It can’t be faster.

Since the speed of light is constant in all frames of reference, this presents a problem. If you’re sitting in your backyard and you turn on your flashlight, the photons shoot away from you at the speed of light, but if you are inside the Red Queen’s Maserati spaceship traveling at close to the speed of light—which is not really possible—and you turned on a flashlight inside the ship, its light would still move away from you at the speed of light, taking into account the slight reduction in speed because of the atmosphere in the ship. You would expect it to slowly move out of your flashlight, but it doesn’t. The speed of light is a constant, no matter what your frame of reference is. But remember, space and time—or rather, spacetime—are distorted at this speed.

By now you’re probably thinking that this doesn’t make sense and can’t be right. That’s pretty much what the world’s physicists thought when Einstein published his ideas and they worked hard to disprove them, but the experiments sided with Einstein. And they are still being confirmed today.

I said it’s not possible for a ship to travel close to the light speed. This is a consequence of his famous formula E = mc², which says that energy is equal to mass, when mass is multiplied by the speed of light squared to convert it into the same units as energy. This means that mass (the amount of matter, disregarding volume) and energy are essentially the same thing and equivalent as far as the equations go. So, the faster a ship goes, the more kinetic energy—the energy of its motion—it gains and the more massive it becomes. As you approach the speed of light, your mass would increase towards infinity, preventing you from reaching light speed. If you were to go faster, your mass would become negative, which doesn’t make sense. You’d also go backwards in time. Energy has no mass when it’s in the form of electromagnetic waves, such as light or radio waves which is why they travel at light speed, but without mass you can’t have a spaceship.

Now, the ship’s stationary mass doesn’t change. It’s the energy you put into it to make it go faster that increases. The mass in the E = mc² equation doesn’t refer to mass like in a rock—it’s the stationary mass, plus kinetic energy acting like extra mass.

As you near the speed of light and your mass approaches infinity, the amount of energy needed to reach full speed also moves towards infinity. In addition, measurements and time shorten as your velocity increases, so as you near light speed, the ship becomes two-dimensional in the direction of travel and time would almost stop. This is a consequence of Einstein’s special theory of relativity and we’ll look at that more closely in a bit. Only massless objects—photons, and possibly zero-mass neutrinos and gravitons (if they exist)—travel at the speed of light. And they don’t have to build up to that speed; they are created at that speed. In a vacuum, that’s the only speed they can go.

For objects with mass, you put in energy to make them go faster. Light doesn’t work that way. If you add energy, or the falling effect of gravity, it increases the frequency of light’s waves. Thus if you have red light and pump in energy, you can shift it to blue or ultraviolet light, or push it to x-rays or gamma rays. But you can’t make it go faster.

Theoretically you can travel farther than the speed of light allows, but you’d have to use a wormhole as a shortcut. There are also hypothetical anti-mass particles called tachyons, which arise from a quantum field with “imaginary mass”, that can go faster than light—and for some viewers, backwards in time—but so far no one knows whether they actually exist.

Some galaxies are moving farther apart faster than the speed of light allows, but this doesn’t violate that law because it’s the universe itself that’s expanding. The galaxies aren’t moving faster than light, the space between them is growing because new space is being created, as we’ll see later.

Esmail Golshan Mojdehi, CC BY-SA 3.0 (adjusted).

As a side note, light travels at exactly 299,792,458 meters per second, confirmed to an accuracy of less than 0.01 micron per second (0.0000004 inches, which is the same size as a water molecule). One single-watt light bulb can produce a billion billion photons per second and they will take off across the universe as long as they don’t hit anything. If you turn on your flashlight and point it at the moon, if at least one photon makes it through the atmosphere and beyond without being deflected, it will reach the moon in 1.3 seconds.

To put this in perspective, if you could drive to the moon (238,855 miles), at 60 miles it would take you 166 days to get there, while light does it in 1.3 seconds. And if you could fly at the speed of light, you could go around the earth’s equator almost eight times in a second. Point your flashlight at the sun and your photon would arrive in 8.3 minutes. To Alpha Centauri—a triple star system that are some of our nearest stars, beside the sun—would take 4.3 years. Toward the Andromeda Galaxy, it will take 2.5 million years for your photon to reach its destination.

Since nothing is faster than light, spaceships can’t dodge light weapons, such as high-energy lasers or photon torpedoes, as they do in movies. They would hit you before you knew they were fired. It’s the same with dodging bullets. It can’t be done. The average bullet travels at 2,493 feet per second, so it would pass through you before your brain could register the muzzle flash, let alone respond to it.

 

If you like this, please subscribe below to receive an email the next time I post something wondrous. It's free.

 

I'll post more in this series when I can. There's a lot more to cover.

In the next posts we'll go deeper down the rabbit hole by continuing to explore Einstein's revelations, quantum physics, the multiverses, and other interesting topics affecting reality, such as whether the universe is a simulation and the peculiar nature of time.

Stepping Way Outside the Box (What is Real? 26)

These posts make more sense when read in order.

Please click here for the first article in this series to enter the rabbit hole.

 

Albert Einstein holding an Albert Einstein marionette around 1931. He joked that the puppet wasn’t fat enough, so he crumpled up a letter and stuffed in under its jacket.

If you say the word “genius”, most people think of Einstein. He is one of the world’s most famous scientists, if not the most famous. Following the publication of his strange theories, he quickly became a celebrity—particularly in America, perhaps partly because of his resemblance to America’s great literary genius, Mark Twain.

When Einstein was about four or five years old, someone showed him a compass and he was fascinated by the fact that the needle always points north. He wondered what the invisible force was that kept the needle steady. It was like magic and he wanted to know how such a thing was possible. As he grew older he focused on learning all about electromagnetism, which led him into physics.

At the young age of 26, he published his special theory of relativity which revolutionized our understanding of the universe. That was in 1905 and at that time physicists knew that the speed of light travels at a defined speed from the work of James Clerk Maxwell forty years earlier. Einstein took this and Galileo’s rule that the laws of physics are the same in all non-accelerating frames of reference and—casting other assumptions aside—showed how these two things raised some rather strange implications.

Here are the basics. Special relativity deals with objects in uniform motion relative to those that are considered stationary and insists that the results of experiments performed in both situations will match. In the order that I will discuss them, the implications are:

• Mass and energy are equivalent (E = mc²). Material objects can approach, but not reach, the speed of light.
• Time is not absolute and depends on the observer’s frame of reference. Two people may experience the passage of time as the same, but they would no longer be in sync. This is time dilation.
• Space is not absolute and depends on the observer’s frame of reference. Two people can measure an identical distance, but to each observer, the other’s will appear to be shorter. This is called length contraction.
• For two simultaneous events, one may be seen before the other by one observer, and in reverse order for another observer. This is failure of simultaneity at a distance.
• Time and space are not separate things, but are a unified spacetime.

Let’s take a closer look at these, but we’ll skip over how they arose from the special theory of relativity. Instead we’ll look at what these things mean.

One of the results that came out of this was his famous equation, E = mc². Energy equals mass multiplied by the speed of light squared. Einstein’s formula means that matter is a concentrated form of energy. Fortunately it’s not easy to release it. If the average person could release all the energy packed away in his or her body, the resulting explosion would equal that of more than 66,000 nuclear bombs like the one the United States used to destroy Nagasaki, Japan. Going the other way, it also means that photons of light can create matter, and physicists have accomplished that.[1]

Nuclear fission and fusion can release or absorb energy depending on which elements are involved. Nuclear fission splits heavy elements into lighter ones by dividing an element’s nucleus into two or more smaller nuclei. Fission is used in atomic bombs, while fusion is used in hydrogen bombs.

During fusion, the sun, for example, fuses lighter elements into slightly heavier ones, which releases energy that comes to us as sunlight. Plants turn the sunlight back into mass to form their leaves and such. After eating the plants, we convert it back into energy to run our bodies. Energy is converted into mass and mass into energy. It is just a temporary change in its state.

Both mass and energy come in different forms. Mass can be inertial mass or gravitational mass. Common forms of energy include nuclear, electrical, kinetic, elastic, thermal, chemical, radiant, gravitational, and potential. But the overall amount of energy and mass in a closed system never changes. That’s the First Law of Thermodynamics—the conservation of energy. Einstein added mass to that law, since he showed that energy and mass are equivalent. The difference is in its state, and that is temporary.

 

If you like this, please subscribe below to receive an email the next time I post something wondrous. It's free.

 

Click here for the next article in this series:

The Fastest Thing in the Universe

---

[1] Jeffrey Winters, “Let There Be Matter”, Discover Magazine, December 1997, p. 40, https://www.discovermagazine.com/the-sciences/let-there-be-matter, November 30, 1997.