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If someone were to die on the moon, would their body decay?

If someone were to die on the moon, would their body decay?


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I heard that the footprints of Neil Armstrong are still there, so I was wondering if someone were to die there, would they remain preserved, too?

If not how long would it take for them to decay?


I am assuming in spacesuit here, on the face (lit side) of the moon. Bodily degradation involves much more than external fungi and bacteria.

Cells that receive no oxygen or nutrients die. We talk of such tissue death as dry gangrene when it affects extremities, such as fingers, feet, etc. However, we also recognize gangrenous bowel, etc. which results in tissue necrosis.

Such necrotic cell death is the consequence of acute disruption of cellular metabolism, leading to ATP depletion, ion dysregulation, mitochondrial and cellular swelling, activation of degradative enzymes, plasma membrane failure and cell lysis [1]

Lysis is messy and wet. Combined with the fluids in our bodies, what one would end up with is a mushy, smelly degraded body, not a preserved body. For a while, anaerobic bowel bacteria would flourish (which smell terrible).

Add to this the extremes of temperature (253° F in the sun and -243° F in the dark.) The suit would have lost it's heating and cooling mechanisms, so the body would alternately spend 14 days in the heat and 14 days in the freezing cold depending exactly where it was (lets say the equator of the moon.) These freeze/bake cycles would further contribute to degradation through ice crystal formation and thawing.

Eventually, because there was no new substrate, degradation would come to a halt, but I'm not sure at what stage this would be. I assume, though, there would be a vast difference between a mummified body (done by dehydration) and a body left to degrade in a spacesuit.

[1] The mitochondrial permeability transition in cell death: a common mechanism in necrosis, apoptosis and autophagy, John J. Lemasters et. al, Biochimica et Biophysica Acta 1366 (1998) 177-196


Decay is a process where the body is digested by bacteria, fungi and other living things.

The moon has no known biological processes and while its possible for some microorganisms to survive in space, I think its generally understood that the lunar surface would not support life in a significant way, especially if the body is in vacuum.

Other processes would definitely take place. Mummification can result from the body dehydrating and direct exposure to solar radiation will also break down the corpse, but it will mostly leave the body intact.


I think the body would undergo decay. While it is true that the moon does not contain living organisms capable of decaying a dead human body, the human body itself contains huge load of bacteria→ on skin surface and gut which will continue to grow.

The aerobic bacteria will die out as soon as oxygen is removed which is very soon. The anaerobic bacteria will continue to grow and proliferate till substrate (dead human body) will cease to exist. This will be regulated as anongoodnurse has pointed out by the heat and light.

Further, the infectious status of the dead person will also matter. Any fungal infection can alter the rate of decay.


What happens to the unprotected human body in space?

As demonstrated by the ailments that plague ISS astronauts returning to Earth, we're simply not built for space. What would happen to a human fired out of an airlock?

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It's a recurring horror in sci-fi: the hull is pierced, a human is trapped without equipment in an airlock about to open, a door needs to be opened in order to expel something undesirable. With no air and almost zero pressure, the human body isn't going to last long without some form of protection.

But what does happen, exactly? Do your eyes explode outward while your blood evaporates? Well, no. The truth is both less dramatic and far more fascinating -- as we have discovered through accidents in space and in test chambers, and animal experimentation in the 1960s.

The first thing you would notice is the lack of air. You wouldn't lose consciousness straight away it might take up to 15 seconds as your body uses up the remaining oxygen reserves from your bloodstream, and -- if you don't hold your breath -- you could perhaps survive for as long as two minutes without permanent injury.

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If you do hold your breath, the loss of external pressure would cause the gas inside your lungs to expand, which will rupture the lungs and release air into the circulatory system. The first thing to do if you ever find yourself suddenly expelled into the vacuum of space is exhale.

The other things, you can't really do much about. After about 10 seconds or so, your skin and the tissue underneath will begin to swell as the water in your body starts to vaporise in the absence of atmospheric pressure. You won't balloon to the point of exploding, though, since human skin is strong enough to keep from bursting and, if you're brought back to atmospheric pressure, your skin and tissue will return to normal.

It also won't affect your blood, since your circulatory system is able to keep your blood pressure regulated, unless you go into shock. The moisture on your tongue may begin to boil, though, as reported by Jim LeBlanc, who was exposed to near vacuum in a test chamber in 1965. LeBlanc's suit sprung a leak, and he remained conscious for about 14 seconds his last sensation was bubbling on his tongue (he was safely revived, as the researchers began repressurising the chamber almost immediately -- after about 15 seconds).

Because you will be exposed to unfiltered cosmic radiation, you can expect some nasty sunburn, and you'll probably also get a case of decompression sickness.You would not, however, freeze straight away, despite the extremely cold temperatures heat does not leave the body quickly enough for you to freeze before you suffocate, due to the lack of both convection and conduction.

If you do die in space, your body will not decompose in the normal way, since there is no oxygen. If you were near a source of heat, your body would mummify if you were not, it would freeze. If your body was sealed in a space suit, it would decompose, but only for as long as the oxygen lasted. Whichever the condition, though, your body would last for a very, very long time without air to facilitate weathering and degradation. Your corpse could drift in the vast expanse of space for millions of years.


Radioactive plutonium and uranium

All radioactive material, as it decays, can cause harm. As unstable radioactive isotopes, or versions of an element with different molecular weights, decay into slightly more stable versions, they release energy. This extra energy can either directly kill cells or damage a cell's DNA, fueling mutations that may eventually lead to cancer.

Plutonium, one of the radioactive substances that may be present at the Hanford site, has a half-life of 24,000 years, meaning that's how long it takes for half of the material to decay into more stable substances. As such, it sticks around in the environment, and in the body, for a long time.

Plutonium exposure can be very deadly for living creatures. A 2011 study in the journal Nature Chemical Biology found that rat adrenal-gland cells ferried plutonium into the cells the plutonium entered the body's cells largely by taking the natural place of iron on receptors. That study found that plutonium also can linger preferentially in the liver and blood cells, leaching alpha radiation (two protons and neutrons bound together). When inhaled, plutonium can also cause lung cancer.

However, because the human body still slightly prefers iron to plutonium for its biological processes, that preference could potentially provide avenues for treating plutonium exposure, by flooding such receptors and preventing plutonium from being taken in by the cells, the study authors noted.

In addition, a 2005 study in the journal Current Medicinal Chemistry found that there are some short-term treatments for plutonium exposure. Studies in the 1960s and 1970s identified agents, such as Diethylenetriaminepentaacetic, which can help the body remove plutonium faster. Other drugs, such as ones used to treat iron-processing disorders such as beta-thalassemia, or bone-strengthening drugs that treat osteoporosis, may also be useful for plutonium exposure, the study found.

Uranium, another radioactive element that may be present at dangerous concentrations in the PUREX tunnel, also can have harmful effects on human health. Uranium isotopes have half-lives ranging from 4.5 billion years to 25,000 years.

The biggest health risk people face after being exposed to uranium is kidney damage, according to the Centers for Disease Control and Prevention. People exposed to uranium may also experience lung problems, such as scar tissue (fibrosis) or emphysema (large air sacs in the lungs). At high doses, uranium can directly cause kidneys and lungs to fail, according to the CDC. However, studies have found that people who drink well water containing low doses of uranium do not show any marked changes in kidney function.

Like plutonium, uranium emits alpha radiation. Uranium may also decay into radon, which has been tied to an increased cancer risk in several studies, particularly in miners who are exposed to higher levels of the toxin.

It's not clear whether there are other radioactive substances in the Hanford site area, but radioactive forms of iodine and cesium can also cause problems such as thyroid cancer, Live Science previously reported.


This Is Your Body. This Is Your Body on Mars

In our daily lives, gravity is that pedestrian physical force that keeps us glued to the ground. You have to go out of your way -- climb a cliff face or jump out of a plane -- before it starts demanding your attention.

But we are constantly sensing the effects of gravity and working against them, largely unconsciously.

[Kevin Fong](https://twitter.com/Kevin_Fong) is a doctor of medicine who also holds degrees in astrophysics and engineering. He is an honorary senior lecturer in physiology at University College London as well as founder and co-director of its Centre for Altitude, Space, and Extreme environment medicine. Fong worked with NASA’s Human Adaptation and Countermeasures Office at Johnson Space Centre in Houston and the Medical Operations Group at Kennedy Space Centre in Cape Canaveral.

Without the quadriceps, buttocks, calves, and erector spinae that surround the spinal column and keep it standing tall, the pull of gravity would collapse the human body into a fetal ball and leave it curled close to the floor. These muscle groups are sculpted by the force of gravity, in a state of constant exercise, perpetually loaded and unloaded as we go about our daily lives. That's why the mass of flesh that constitutes the bulk of our thighs and works to extend and straighten the knee are the fastest-wasting group in the body.

In experiments that charted the changes in the quadriceps of rats flown in space, more than a third of the total muscle bulk was lost within nine days.

Our bones, too, are shaped by the force of gravity. We tend to think of our skeleton as pretty inert -- little more than a scaffold on which to hang the flesh or a system of biological armor. But at the microscopic level, it is far more dynamic: constantly altering its structure to contend with the gravitational forces it experiences, weaving itself an architecture that best protects the bone from strain. Deprived of gravitational load, bones fall prey to a kind of space-flight-induced osteoporosis. And because 99 percent of our body’s calcium is stored in the skeleton, as it wastes away, that calcium finds its way into the bloodstream, causing yet more problems from constipation to renal stones to psychotic depression.

Medical students remember this list as: “bones, stones, abdominal groans, and psychic moans”.

The biological adaptations to gravity don’t stop there. When we’re standing up, our heart, itself a muscle pump, has to work against gravity, pushing blood vertically in the carotid arteries that lead away from our heart toward our brain. When deprived of the need to work against the force of gravity, the heart and its system of vessels become deconditioned -- slowly taking athletes and turning them into couch potatoes.

The system of accelerometers in our inner ear, the otoliths and semicircular canals, are engineered to provide the finest detail about movement, sharing their inputs and outputs with the eyes, the heart, the joints, and the muscles. These organs are not considered “vital” in the sense that they are not required to keep the human body alive. As a result, the essential role they play in delivering a finely calibrated sense of motion is often overlooked.

Like all of the best things in life, you don’t really appreciate what you’ve got until you lose it. Imagine a gently oscillating, nausea-inducing scene from which there is no escape. That’s what it feels like when the organs of the inner ear malfunction. And that can be caused by disease, drugs, poisons, and -- as it turns out -- the absence of gravity.

The impairments don’t stop there. There are other, less well-understood alterations. Red blood cell counts fall, inducing a sort of space anemia. Immunity suffers, wound healing slows, and sleep is chronically disturbed.

Deprived of the need to work against the force of gravity, the body becomes deconditioned — taking athletes and turning them into couch potatoes.

There are a number of formidable problems that accompany long-stay missions. The first is life support. How do we invent a system that can keep a crew of four alive for nearly three years?

For space stations, breathable oxygen requires electrolyzing a steady supply of water. But there is no easy way to resupply a team traveling to Mars, and so a number of ingenious solutions to this problem have been proposed.

One involves a grow-your-own approach to life support and nutrition. It turns out that if you grow 10,000 wheat plants, you can generate more than enough oxygen to breathe while removing the human waste gas of carbon dioxide. Better still, you have a partial source of nutrition. For a while, the Space Center had a team of four volunteers locked up in a hermetically sealed tube, subsisting pretty independently on this self-regenerating, hydroponically grown life-support system.

And that’s all great -- until you factor in the possibility of crop failure.

Another solution, discussed at a European Space Agency human space-exploration symposium, would be to grow vats of algae (which might be easier to sustain than wheat and would also provide a source of protein). Between that and the wheat plants, you could get halfway to a diet of pizza-like food -- bread coated with flavored algae -- and massively reduce the weight and volume of the food and life-support apparatus required for a Mars mission. A Frenchman who specialized in the field of regenerative life support told me how this might work, going so far as to explain the recycling of urine and the use of feces as a source of fertilization.

“You see,” he shouted above the din of the bar, “these people who go to Mars, they will literally ’av to eat their own shit.”

If that hasn’t put you off the trip already, then consider the radiation hazards. As far as anyone can tell, the background radiation we would be exposed to while traveling between Earth and Mars should be within safe limits … unless there’s a solar flare. A solar flare is like a neutron bomb going off next to you. Energetic particles -- charged helium nuclei, neutrons, protons, and the like -- would pass through our body, wreaking havoc and irreversibly damaging cells. (Lead and other heavy metal coating wouldn’t help when it comes to highly energetic heavy particles.)

Even if we figure out a way to negotiate the radiation and build a life-support system that is at least partly regenerative, we keep getting back to the most elemental problem: having to contend with the absence of gravity.

In our daily lives, our physiology is maintained by only intermittent exposure to gravitational load -- the standing up and stomping around we do during the day. Indeed, when researchers want to mimic the effects of microgravity here on Earth, they simply send a bunch of people to bed.

From this realization grew the idea that we might prescribe gravity like a drug, giving it in short but large doses. NASA went out and built it. Early results from NASA’s Artificial Gravity Pilot Project suggested that the heart and muscles might be usefully protected in this way. It would be surprising if bone didn’t benefit too. But the inner ear and its organs of accelerometry are a different story.

Sadly, it doesn’t seem that we’ll find out the answers anytime soon. In 2009, just as the artificial-gravity project was ready to enter a more comprehensive phase of investigation, a series of budget cuts tore through NASA. The strategy that would have seen a short-arm centrifuge investigated thoroughly on the ground and then made ready for flight aboard the space station was canned.

Excerpted and adapted from Extreme Medicine, by arrangement with The Penguin Press, a member of Penguin Group (USA) LLC, A Penguin Random House Company. Copyright Kevin Fong, 2014.


How long would bodies be preserved on the Moon? If astronauts died there, what would happen to their bodies?

Say Buzz Aldrin and that other guy (fun right?) happened to be stranded and ate the cyaniade outside the lunar lander, how would their body decompose? In the suit.

The lunar surface temperature at the equator fluctuates between 100 Kelvin and 390 Kelvin (116C). Apollo 11 landed at 0.8° N, 23.5° E. If there were any that bacteria could survive extreme temperatures(??) they might have an opportunity to decompose the bodies. Also cyclic thawing and refreezing would slowly start turning the bodies to slush. Eventually the materials of the suit would become damaged either through metal fatigue, ice crystals forming, or micrometeorites, this would result in a a leak, all the gasses and liquids would evaporate and escape. At which point the freezing thawing cycle would stop.

I have no idea how long it would take for the suit to start leaking, or how far along the freezing/thawing cycle would be.

After that point the only things that could further degrade the bodies would be radiation exposure breaking down organic molecules, cyclic heating and cooling from exposure to the sun causing metal fatigue etc on the suit, micrometeorites and ionized lunar dust

Would they still be recognisable as human bodies in 1 million years? I have no idea.


7 Be An Ice Cube

If you don&rsquot like getting your feet wet, you could always try promession, or freeze-drying your remains. The proposed method of promession would use liquid nitrogen to freeze-dry your corpse while extracting the water, which comprises 60 percent of our bodies.

Bodies would be frozen at around minus 200 degrees Celsius (� °F) so that they become extremely brittle. They would then be vibrated with sound waves until they turn to dust, with the exception of any fillings or surgical implants. The dust would be collected and handed back to the family. [4]

You could put the dust in a biodegradable coffin and bury it so that it turns into compost in around a year. But, then, what do you do with the compost? The problem seems to be never-ending. Ultimately, however, the company that would have offered promession went under before any remains could be promessed.


WATCH: This Is Exactly What Happens When You Die

Death is everywhere. Every single minute, an average of 100 people die somewhere in the world, and we humans aren't great at coming to terms with that, or the inevitability of our own demise. But understanding how our bodies end up when they finally give out is a crucial part of knowing how they function in life, so AsapSCIENCE is here to take us through a blow-by-blow account of death, according to science.

Within seconds of death, your body's supply of oxygen will be depleted, and your brain activity surges. This might sound a little counter-intuitive, seeing as dead people don't have thoughts, but you can think of this activity as the last dying bursts of activity from neurons that are no longer supported by oxygen and hormone production.

The body's stores of adenosine triphosphate (ATP) - the body's main source of energy - are also depleted, so following any last-second twitches, your muscles will totally relax, including sphincter. This means if your bowels were full at the time of death, they won't be for very long. (We told you this would be morbid.)

In light-skinned people, your body won't start taking on that stale deathly hue until about 15 to 20 minutes after death, at which point the lack of blood flow to the capillaries starts to drain the colour out of you.

And if that sounds gross, think about this - because your heart has stopped pumping, there's nothing pushing your blood around your body, so depending on how your body is positioned when you die, the blood will end up pooling around down the bottom.

As the video above explains, the longer this 'blood pooling' is left to sit, the more your skin will take on a reddish-purple discolouration, which will hit its maximum intensity at around the 12-hour mark.

It's not the nicest thing in the world to think about, but the way our blood pools and discolours our skin can tell coroners a whole lot about when we died, and how we were positioned at the time of death.

At around 3 to 6 hours after death, your body will experience the infamous process of rigor mortis. This occurs because when your cell organelles start deteriorating, they release calcium into muscle cells, and these bind to proteins that are responsible for muscle contraction. This means that your body will completely stiffen up, and you could be stuck in a really strange position for as long as 24 to 48 hours after death.

By this point, hopefully someone has found you, because decay is well and truly on its way. I'll let the boys from AsapSCIENCE explain all the gory details of that process in the video above, but let's just say you're going to get up close and personal with a little thing called putrefaction, and it's about as pleasant as it sounds. Enjoy.

And now that you know the science behind what happens to the corpse, check out the video below of the world's largest body farm, which is giving scientists the opportunity to learn even more about what death does to our bodies, thanks to a number of donated corpses. Warning: this is not easy watching, please mentally prepare yourself before clicking play!


What happens during the dying process?

The Scout motto is "be prepared," but it's hard to be prepared for death, be it our own or a loved one's. Too much is unknown about what dying feels like or what, if anything, happens after you die to ever feel truly ready. However, we do know a bit about the process that occurs in the days and hours leading up to a natural death, and knowing what's going on may be helpful in a loved one's last moments.

During the dying process, the body's systems shut down. The dying person has less energy and begins to sleep more and more. The body is conserving the little energy it has, and as a result, needs less nourishment and sustenance. In the days (or sometimes weeks) before death, people eat and drink less. They may lose all interest in food and drink, and you shouldn't force them to eat. In fact, pushing food or drink on a dying person could cause him or her to choke -- at this point, it has become difficult to swallow and the mouth is very dry.

As the person takes in less food and drink, he or she will urinate less frequently and have fewer bowel movements. The person may also experience loss of bladder and bowel control. People who are dying may become confused, agitated or restless, which could be a result of the brain receiving less oxygen. It can be disconcerting and painful to hear a loved one so confused in his or her last days.

The skin will also show the effects of slowing circulation and less oxygen -- the extremities, and later, the entire body, may be cool to the touch and may turn blue or light gray. Some skin may exhibit signs of mottling, which is reddish-blue blotchiness. As the person gets closer to death, it will become harder and harder to breathe. Respiration will be noisy and irregular it will sometimes seem as if the person can't breathe at all. When there's fluid in the lungs, it can cause a sound known as the death rattle. It may be possible to alleviate the gurgling and congestion by raising the person's head. If the dying person is experiencing pain, he or she will usually be given medications to manage it.

When we're watching someone die, we may have a preconceived notion of how the person should handle death emotionally and spiritually. It's important to remember that every person experiences dying differently. Some people have the need to say goodbye or to hear from another person before death, some don't. Some people prefer to partake in religious rites, while others may remain silent until the end and pass away when everyone has left the room. Doctors and other professionals who manage end-of-life care advise loved ones to take their cues from the dying and avoid projecting their own desires or needs onto the person. They also urge loved ones to continue speaking comfortingly to a dying person -- hearing may be one of the last things to go.

Clinical death occurs when the person's heartbeat, breathing and circulation stop. Four to six minutes later, biological death occurs. That's when brain cells begin to die from lack of oxygen, and resuscitation is impossible.


How Body Farms Work

In order to understand how body farms work, it helps to know some basics about human death and decay. Though it sounds pretty macabre, it's perfectly normal for your body to go through some radical changes when you die.

To begin with, when your heart stops beating, your body's cells and tissues stop receiving oxygen. Brain cells are the first to die -- usually within three to seven minutes [source: Macnair]. (Bone and skin cells, though, will survive for several days.) Blood begins draining from the capillaries, pooling in lower-lying portions of the body, creating a pale appearance in some places and a darker appearance in others.

About three hours after death, rigor mortis -- a stiffening of muscles -- sets in. Around 12 hours after death, the body will feel cool, and within 24 hours (depending on body fat and external temperatures), it will lose all internal heat in a process called algor mortis. The muscle tissue begins to lose its stiffness after about 36 hours, and within about 72 hours of dying, the body's rigor mortis will subside.

As the cells die, bacteria within the body begin breaking them down. Enzymes in the pancreas cause the organ to digest itself. The body soon takes on a gruesome appearance and smell. Decomposing tissue emits a green substance, as well as gasses such as methane and hydrogen sulfide. The lungs expel fluid through the mouth and nose.

Insects and animals certainly take notice of all this. A human body provides sustenance and a great place for insects to lay eggs. A fly trying to find its way in this crazy, mixed-up world can eat well on a corpse, and then lay up to 300 eggs upon it that will hatch within a day.

Maggots -- the larvae that emerge from these eggs -- are extremely efficient and thorough flesh-eaters. Starting on the outside of the body where they hatched, maggots use mouth hooks to scoop up the fluids oozing out of the corpse. Within a day's time, the maggots will have entered the second stage of their larval lives, as well as burrowing into the corpse.

Moving around as a social mass, maggots feed on decaying flesh and spread enzymes that help turn the body into delectable goo. The breathing mechanism of a maggot is located on the opposite end of its mouth, enabling it to simultaneously eat and breathe without interruption around the clock. While a first-stage larva is about 2 millimeters long, by the time it exits the third stage and leaves the body as a prepupa, it may be as large as 20 millimeters -- 10 times its initial length. Maggots can consume up to 60 percent of a human body in under seven days [source: Australian Museum].

The environment in which a dead body is placed also affects its rate of decay. For instance, bodies in water decompose twice as fast as those left unburied on land. Decomposition is slowest underground -- especially in clay or other solid substances that prevent air from reaching the body since most bacteria require oxygen to survive.

Now that we know more about human decay, we'll look at a group of people whose workplace smacks strongly of it: forensic anthropologists.

It once was commonly believed that nails and hair continued to grow on a dead body. To the casual observer, it would seem true. However, this visual effect is caused by shrinkage of the skin, scalp and cuticles.


Physics and the Immortality of the Soul

The topic of "life after death" raises disreputable connotations of past-life regression and haunted houses, but there are a large number of people in the world who believe in some form of persistence of the individual soul after life ends. Clearly this is an important question, one of the most important ones we can possibly think of in terms of relevance to human life. If science has something to say about, we should all be interested in hearing.

Adam Frank thinks that science has nothing to say about it. He advocates being "firmly agnostic" on the question. (His coblogger Alva Noë resolutely disagrees.) I have an enormous respect for Adam he's a smart guy and a careful thinker. When we disagree it's with the kind of respectful dialogue that should be a model for disagreeing with non-crazy people. But here he couldn't be more wrong.

Adam claims that there "simply is no controlled, experimental[ly] verifiable information" regarding life after death. By these standards, there is no controlled, experimentally verifiable information regarding whether the Moon is made of green cheese. Sure, we can take spectra of light reflecting from the Moon, and even send astronauts up there and bring samples back for analysis. But that's only scratching the surface, as it were. What if the Moon is almost all green cheese, but is covered with a layer of dust a few meters thick? Can you really say that you know this isn't true? Until you have actually examined every single cubic centimeter of the Moon's interior, you don't really have experimentally verifiable information, do you? So maybe agnosticism on the green-cheese issue is warranted. (Come up with all the information we actually do have about the Moon I promise you I can fit it into the green-cheese hypothesis.)

Obviously this is completely crazy. Our conviction that green cheese makes up a negligible fraction of the Moon's interior comes not from direct observation, but from the gross incompatibility of that idea with other things we think we know. Given what we do understand about rocks and planets and dairy products and the Solar System, it's absurd to imagine that the Moon is made of green cheese. We know better.

We also know better for life after death, although people are much more reluctant to admit it. Admittedly, "direct" evidence one way or the other is hard to come by -- all we have are a few legends and sketchy claims from unreliable witnesses with near-death experiences, plus a bucketload of wishful thinking. But surely it's okay to take account of indirect evidence -- namely, compatibility of the idea that some form of our individual soul survives death with other things we know about how the world works.

Claims that some form of consciousness persists after our bodies die and decay into their constituent atoms face one huge, insuperable obstacle: the laws of physics underlying everyday life are completely understood, and there's no way within those laws to allow for the information stored in our brains to persist after we die. If you claim that some form of soul persists beyond death, what particles is that soul made of? What forces are holding it together? How does it interact with ordinary matter?

Everything we know about quantum field theory (QFT) says that there aren't any sensible answers to these questions. Of course, everything we know about quantum field theory could be wrong. Also, the Moon could be made of green cheese.

Among advocates for life after death, nobody even tries to sit down and do the hard work of explaining how the basic physics of atoms and electrons would have to be altered in order for this to be true. If we tried, the fundamental absurdity of the task would quickly become evident.

Even if you don't believe that human beings are "simply" collections of atoms evolving and interacting according to rules laid down in the Standard Model of particle physics, most people would grudgingly admit that atoms are part of who we are. If it's really nothing but atoms and the known forces, there is clearly no way for the soul to survive death. Believing in life after death, to put it mildly, requires physics beyond the Standard Model. Most importantly, we need some way for that "new physics" to interact with the atoms that we do have.

Very roughly speaking, when most people think about an immaterial soul that persists after death, they have in mind some sort of blob of spirit energy that takes up residence near our brain, and drives around our body like a soccer mom driving an SUV. The questions are these: what form does that spirit energy take, and how does it interact with our ordinary atoms? Not only is new physics required, but dramatically new physics. Within QFT, there can't be a new collection of "spirit particles" and "spirit forces" that interact with our regular atoms, because we would have detected them in existing experiments. Ockham's razor is not on your side here, since you have to posit a completely new realm of reality obeying very different rules than the ones we know.

But let's say you do that. How is the spirit energy supposed to interact with us? Here is the equation that tells us how electrons behave in the everyday world:

Don't worry about the details it's the fact that the equation exists that matters, not its particular form. It's the Dirac equation -- the two terms on the left are roughly the velocity of the electron and its inertia -- coupled to electromagnetism and gravity, the two terms on the right.

As far as every experiment ever done is concerned, this equation is the correct description of how electrons behave at everyday energies. It's not a complete description we haven't included the weak nuclear force, or couplings to hypothetical particles like the Higgs boson. But that's okay, since those are only important at high energies and/or short distances, very far from the regime of relevance to the human brain.

If you believe in an immaterial soul that interacts with our bodies, you need to believe that this equation is not right, even at everyday energies. There needs to be a new term (at minimum) on the right, representing how the soul interacts with electrons. (If that term doesn't exist, electrons will just go on their way as if there weren't any soul at all, and then what's the point?) So any respectable scientist who took this idea seriously would be asking -- what form does that interaction take? Is it local in spacetime? Does the soul respect gauge invariance and Lorentz invariance? Does the soul have a Hamiltonian? Do the interactions preserve unitarity and conservation of information?

Nobody ever asks these questions out loud, possibly because of how silly they sound. Once you start asking them, the choice you are faced with becomes clear: either overthrow everything we think we have learned about modern physics, or distrust the stew of religious accounts/unreliable testimony/wishful thinking that makes people believe in the possibility of life after death. It's not a difficult decision, as scientific theory-choice goes.

We don't choose theories in a vacuum. We are allowed -- indeed, required -- to ask how claims about how the world works fit in with other things we know about how the world works. I've been talking here like a particle physicist, but there's an analogous line of reasoning that would come from evolutionary biology. Presumably amino acids and proteins don't have souls that persist after death. What about viruses or bacteria? Where upon the chain of evolution from our monocellular ancestors to today did organisms stop being described purely as atoms interacting through gravity and electromagnetism, and develop an immaterial immortal soul?

There's no reason to be agnostic about ideas that are dramatically incompatible with everything we know about modern science. Once we get over any reluctance to face reality on this issue, we can get down to the much more interesting questions of how human beings and consciousness really work.

Sean Carroll is a physicist and author. He received his Ph.D. from Harvard in 1993, and is now on the faculty at the California Institute of Technology, where his research focuses on fundamental physics and cosmology. Carroll is the author of From Eternity to Here: The Quest for the Ultimate Theory of Time, and Spacetime and Geometry: An Introduction to General Relativity. He has written for Discover, Scientific American, New Scientist, and other publications. His blog Cosmic Variance is hosted by Discover magazine, and he has been featured on television shows such as The Colbert Report, National Geographic's Known Universe, and Through the Wormhole with Morgan Freeman. His Twitter handle is @seanmcarroll

The views expressed are those of the author and are not necessarily those of Scientific American.

The views expressed are those of the author(s) and are not necessarily those of Scientific American.