Universe expected to decay in 10⁷⁸ years, much sooner than previously thought

https://phys.org/news/2025-05-universe-decay-years-sooner-previously.html

by pseudolus • 1 year ago

225 304 1 year ago

Etheryte• 1 year ago

So Hawking radiation moves the estimate from the previous 10^1100 to 10^78 years. That's a pretty drastic change, but naturally, not exactly something to go and worry about. Most of us would be lucky to make it to 10^2, so there's still some way to go.

busyant• 1 year ago

get your affairs in order.

coolcase5• 1 year ago

Another 10^3 would be good for humanity

lordfrito• 1 year ago

The exponent going 1100 to 78 is pretty large error... huge 93% reduction... hopefully they have high confidence in the new value, otherwise humanity might be looking at 1 more big problem this century.

immibis2• 1 year ago

It's actually a 99.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999% reduction and yes that is the correct number of 9's.

wewewedxfgdf• 1 year ago

Despite it being quite a way out it's still a little sad to think the end is coming.

rswail4• 1 year ago

"quite a way out"... is doing a lot of work in that sentence.

tobias_irmer• 1 year ago

To me that still sounds like forever.

MOARDONGZPLZ• 1 year ago

I hope they’re working on finding a way to massively decrease the net entropy in the universe after this.

andreareina• 1 year ago

Unfortunately there is as yet insufficient data for a meaningful answer

watt• 1 year ago

Crack on with it and don't keep us in the dark!

coolcase5• 1 year ago

The way to do that is to do the most unlikely things

dvh• 1 year ago

Previous studies, which did not take this effect into account, put the lifetime of white dwarfs at 10^1100 years

That's some kind of typo no? I've only heard previous estimates for white dwarf to be trillions of years, that is significantly shorter that 10^1100

Edit: never mind, by lifetime that me proton decay, not how long they shine light

vijaybritto2• 1 year ago

My shower is theory is that there are infinite universes getting created all the time and we can never know about it because we're restricted in this universe. I love having these talks with my daughter.

Y_Y• 1 year ago

There's a teapot orbiting the sun between Earth and Mars too.

A_D_E_P_T3• 1 year ago

That's almost the mainstream position in physics as of 2025 -- that cosmic inflation never stopped, that it produces universes beyond number, and we're in one pinched-off region of it.

You'd like this book: https://mitpress.mit.edu/9780262547222/an-infinity-of-worlds...

vijaybritto2• 1 year ago

This is beautiful!

hinkley10• 1 year ago

The trouble would be that even if we sensed other universes we might not be able to go there unless we can create our own pocket universes. There's no guarantee that an adjacent universe has the same rules of physics.

All of the enzymes in your body might stop working if you stepped into even a slightly different universe. You could just turn into a gas, and not in a good way.

m1117• 1 year ago

AI is going to take over anyways

coolcase5• 1 year ago

It'll be 42'd like everything else

Aetheridon• 1 year ago

so i wonder what comes after?

willis936• 1 year ago

A fun tool to think around such things are Penrose diagrams. Personally I'm a little dubious of strong claims of what will happen in the distant future since we have such incomplete models of physics today. It takes GUTs to predict the future.

https://youtu.be/mht-1c4wc0Q

voidUpdate• 1 year ago

The Credits

Lerc2• 1 year ago

If there is nothing left, does time pass? Does it pass but is meaningless? Does it no longer exist?

The same question goes for space. Is there any size to the nothingness? To go further when you have notions like inflation, can you have nothing that is increasing in volume? That would suggest a change in state an thus a sense of not yet ended.

It would be a weird thing for nothingness to change state. It seems like fertile soil for sci-fi. Imagine if space itself was kind of Turing complete and once the noise of matter ended it could start the real work, which of course would be simulating the next universe.

coolcase5• 1 year ago

There is a theory out there that once heat death is done distance is meaningless, therefore zero, therefore big bang again.

mr_toad2• 1 year ago

It would be a weird thing for nothingness to change state.

If there are no physical laws, there’s nothing to stop that happening.

rswail4• 1 year ago

That question makes no sense in terms of this discussion. The heat death of the universe means that there is no "after", just as there was no "before" the Big Bang.

The actual concept of time does not exist (at least in my humble year 12 physics understanding and having read Brief History Of Time a long time ago :) )

kergonath• 1 year ago

having read Brief History Of Time a long time ago :)

It pains me to say this, because it is a masterpiece of vulgarisation, putting arcane physics and cosmology within reach of (still decently-educated) normal people, but it is very outdated in a lot of respects. It badly needs something else.

I found some of Carlo Rovelli’s books to be quite compelling, but they are more focused on the topic of time and space-time. Not really the universe in the same way as Hawking’s were.

blueflow2• 1 year ago

It is written

  The researchers calculated that the process of Hawking radiation theoretically also applies to other objects with a gravitational field

but: doesn't this only apply if these objects if they have some sort of decay process going on? There are nuclides that have never been observed decaying. I would expect a white dwarf to burn out, go through radioactive decay (unstable nuclides -> stable ones) and end up as inert rock (stable nuclides) at background temperature.

dist-epoch2• 1 year ago

Regular "stable nuclides" stuff which falls into a black hole gets spit out as Hawking radiation, so no, this is a gravitational process, radioactive decay is a standard model one.

jfengel• 1 year ago

Hawking radiation doesn't require decay. Pairs of particles appear spontaneously. One falls into the gravitational field, losing energy.

The net energy loss comes from the gravitational field of the object, and its mass decreases. We don't have details on just what that means at a Standard Model level, but the net loss of energy means something is going to disappear even without any kind of previously understood decay.

dist-epoch2• 1 year ago

Pairs of particles appear spontaneously. One falls into the gravitational field, losing energy.

That's not really true. Even Hawking admitted that's it's a simplification he did for his popular science book of what really is going on.

https://www.youtube.com/watch?v=UxVssUb0MsA

mr_toad2• 1 year ago

No, all objects with non-zero temperature radiate heat. Stars, white dwarfs, black holes, even the universe itself.

blueflow2• 1 year ago

I said

  inert rock at background temperature

so radiated and absorbed heat should already be accounted for, right?

pixl975• 1 year ago

here are nuclides that have never been observed decaying

Aren't we pretty sure due to things like quantum tunneling that the probability of any quantum particle existing trends to zero given a long enough time?

cvoss• 1 year ago

The whole point of Hawking radiation is that a thing which famously shouldn't have a decay process (a black hole) in fact does have a decay process due to the interaction of gravity and quantum mechanics.

terabytest• 1 year ago

As someone who doesn’t know much about this, I'm curious:

If humanity survived far into the future, could we plausibly develop ways to slow or even halt the decay of the universe? Or is this an immutable characteristic of our universe, meaning humanity will inevitably fizzle out along with the universe?

saberience• 1 year ago

See The Last Question, by Isaac Asimov:

https://users.ece.cmu.edu/~gamvrosi/thelastq.html

Vox_Leone• 1 year ago

It's interesting to note, that the Universal AC in “The Last Question” did not hallucinate an answer.

Instead, its response—"INSUFFICIENT DATA FOR MEANINGFUL ANSWER"—is a model of intellectual honesty.

mykowebhn3• 1 year ago

Why, so we can extend the 10^78 years? I'm not sure you truly understand how large 10^78 years is, or even 10^10 years.

suddenlybananas• 1 year ago

While it seems doubtful that people will last that long, in 10^78 years, one would think those people alive at the time would want the universe to continue.

diego898• 1 year ago

Very strongly suggest you check out Isaac Asimov’s “The Last Question”

https://users.ece.cmu.edu/~gamvrosi/thelastq.html

brazzy• 1 year ago

Or, for an alternative and rather more in depth treatment, Stephen Baxter's "Manifold: Time"

krapp2• 1 year ago

The Second Law of Thermodynamics is an immutable characteristic of our universe. Entropy in a closed system (like the universe) is irreversible.

exe34• 1 year ago

It was set to zero once, so somebody somewhere/somewhen figured it out before.

yfontana• 1 year ago

We don't know for sure that the universe is a closed system.

felipeerias• 1 year ago

If we survive far into the future, we will learn a lot more about the structure and evolution of the Universe. It might be that the questions that our scientists can ask now will turn out to be trivial or meaningless to our descendants. Perhaps the Universe is far stranger than we can imagine.

ashoeafoot• 1 year ago

The origami of petal unfolding implies the rose blooms forever says all bugkind dwelling on the bud.

AnonC• 1 year ago

I’m not an expert on this, but I read this by Lawrence M Krauss (theoretical physicist and cosmologist):

“In 5 billion years, the expansion of the universe will have progressed to the point where all other galaxies will have receded beyond detection. Indeed, they will be receding faster than the speed of light, so detection will be impossible. Future civilizations will discover science and all its laws, and never know about other galaxies or the cosmic background radiation. They will inevitably come to the wrong conclusion about the universe......We live in a special time, the only time, where we can observationally verify that we live in a special time.”

A billion is just 10 to the power of nine, and that number of years in time is itself a long, long time that’s difficult to imagine. Looking at 10 to the power of 78 is…it wouldn’t matter much for us if it were to the power of 60 either. (I think!) I seriously doubt humans (as we know of now) can meaningfully affect the expansion or decay of the universe.

mellosouls• 1 year ago

In just 5 billion years? This surprises me, trillion I could understand, 5 billion is similar to the age of the earth.

Incidentally, the obvious counter to "our time is special, we have access to everything" is presumably what future civilisations think as well; the implication being perhaps we have lost something over the aeons that would shed light on our current mysteries.

I haven't read the book but it's an unconvincing extract, though I acknowledge a larger context may justify it.

glenstein• 1 year ago

Right so we're limited in time and resources, in a sense. Only some of the universe would be reachable within those 10^1100 or 10^78 years anyway. So we are limited by time but also what we can access.

What's fascinating to me is to consider the frontier of galaxies theoretically reachable within a given window, and the potential race to colonize them before they race away.

analog31• 1 year ago

This is a good reason not to throw away your old textbooks.

isoprophlex• 1 year ago

Is that right? Only 5 billion years until noone sees the background radiation and other galaxies?!

That's... awe inspiring.

Strilanc• 1 year ago

Can you provide the source for that quote? 5 billion years seems way too soon.

The Hubble constant is currently approximately one doubling per 14 billion years [1]. So 5 billion years isn't enough to double the recession speeds. AFAIK there's plenty of galaxies receding at less than half the speed of light. Wikipedia estimates 150 billion years (6000x expansion) for all but the local group to be beyond the horizon [2]. So your quote seems to be off by two orders of magnitude.

[1] https://astronomy.stackexchange.com/questions/49248/interpre...

[2] https://en.wikipedia.org/wiki/Timeline_of_the_far_future

unsupp0rted• 1 year ago

Which leads one to wonder what phenomena we were too late to observe and which of our assumptions are therefore faulty

bee_rider2• 1 year ago

Well, the rest of us will likely die. However, you (the reader of this comment) will only have observed universes in which you don’t die. So, due to quantum immortality and all that, you’ll figure it out I guess. And in some sense humanity will not fizzle out; at least you’ll carry it along.

It is a big project, but don’t worry, you’ve got quite a while to work it all out. I would start working on it in earnest in about a million years. If you wait a couple billion, more of the stuff in the universe might have decayed, and the end result might be less interesting, I guess.

Please tell whatever else is around about the rest of us!

subscribed• 1 year ago

PBS Space Time vibes

GistNoesis• 1 year ago

Time is irrelevant. What matters are units of computations.

When things are predictable they can be simulated fast : A spinning ball in the void can be simulated for 10^78 years in O(1).

When things are fuzzy, they can be simulated fast : A star made of huge number of atoms is not so different than another star made of a huge number of atoms. When processes are too complex they tend to all follow the law of large numbers which makes the computations memoizable.

What you want is a way to prevent the universe from taking shortcuts in its computations. Luckily its quite easy. You have to make details important. That's where chaos theory comes to the rescue. Small perturbations can have big impacts. Bifurcations like tossing a coin in the air create pockets of complexity. But throw too many coins in the air and its just random and boring. Life exists on this edge where enough structure is preserved to allow enough richness to exist.

One way humans have found of increasing precision is the lathe, which lead to building computers. Build a big enough fast enough computer and you will run-out of flops faster than reaching the 10^78 endgame.

But you have to be smart, because computation being universal it means that if you are just building a big computer what matters will be what runs on it. And your universe can be reduced to a recursive endgame state of "universe becoming a computer running universe simulation of a specific type", which doesn't need to computed more than once and already was, or isn't interesting enough to deserve being computed.

That's why we live on the exciting edge before the Armageddon, boring universes having already been simulated. The upside being universe hasn't yet decided which endgame we may reach, because the phytoplankton aliens of k2-18b have not yet turned on their supercomputer.

TOGoS• 1 year ago

This is a wacky, seemingly out-of-place philosophical comment, yet I have had similar thoughts, so I give you an irreverent upvote.

thatguymike• 1 year ago

There's a very entertaining Dwarkesh podcast with Adam Brown about this: https://www.dwarkesh.com/p/adam-brown

mensetmanusman4• 1 year ago

Humans are the universe contemplating this.

BurningFrog• 1 year ago

The only serious answer is that we have absolutely no way of knowing that.

zero_bias6• 1 year ago

Hawking radiation is a very slow process; one can acquire additional matter (e.g., hydrogen atoms from interstellar or intergalactic space) to compensate for the matter loss

anshumankmr• 1 year ago

Here's some food for thought: there are perhaps some things that would be perhaps out of reach for all living beings for the conceivable future and beyond.

We are barely able to handle technological progress that would seem like stone age or even worse to a potential species that may exist at that time (ie those that may have such technology to stop the death of the very universe they are living)

They might just be indistinguishable from a god if there is one. And if they have enough power to perhaps prevent the death of the universe, they might have enough technology to just recreate another one. Or open a wormhole and transport to a new one or travel the multiverse or something.

Basically I feel if such kind of technology can be created to bend the universe to your will, it would be misused so badly, it might be catastrophic for the existence of such a species.

Extropy_• 1 year ago

This is the original paper: https://arxiv.org/abs/2410.14734

They say their findings set "a general upper limit for the lifetime of matter in the universe."

fsiefken• 1 year ago

Ok, well, surviving beyond 1 billion years and various extinction level events, asteroids, comets, nuclear wars, are are the first priority, we'll worry about this later.

Perhaps we can set up a secret program where AI randomly selects individuals based on merit, character to get the latest in life extension treatments, philosophical and spiritual education so they can guide us (with AI assistence) into the future and beyond the solar system.

If we survive, 'we' most probably don't exist by that time in any recognisable shape or form.

NoMoreNicksLeft2• 1 year ago

I suspect we have more immediate problems than "can we survive the next n billion years".

2OEH8eoCRo0• 1 year ago

There have already been close calls with nukes. No way in hell we last another hundred.

rTX5CMRXIfFG• 1 year ago

What values do you think we should optimize for?

Ygg2• 1 year ago

Good. Maybe now they can prove Hawking radiation in something that isn't a bath tub. Or an oven.

Ekaros• 1 year ago

One more argument not to do anything about climate change. After all universe is going decay shortly...

thom• 1 year ago

Ah, just time for another bath. Pass me the sponge somebody, will you?

andrewstuart• 1 year ago

How can the universe come from an infinite point and have no Centre.

acuozzo• 1 year ago

The center is everywhere.

laxd2• 1 year ago

Imagine blowing up an infinitesimally small balloon. Nowhere on the surface will you find the center. Also, as the other comment says, the center is everywhere. We are on the inside of the big bang.

stavros• 1 year ago

Oh no! What are we going to do about this?

maaaaattttt2• 1 year ago

I suppose this time is expressed in earth years? Or what would this duration mean on a Universe scale? Also given the nature of space-time (the time and gravity relationship) wouldn't time be almost still once, let's say, year 10⁷⁷ is reached?

pixl975• 1 year ago

Isn't time relative?

If you were in a place where time was still you'd have no idea it were the case. Time would still tick at one second per second. You could only tell when you looked at some other object/patch of space that had a different ticking clock.

maaaaattttt2• 1 year ago

Time is relative, absolutely (I had to do it, sorry). I guess in these articles they mean 10^77 years for an observer on earth. My understanding is if I was, somehow, waiting inside a black hole it would take much less time for me to observe the universe decaying. And if i'm not mistaken, then I wonder what does that mean for the universe as a whole. Maybe the question doesn't make sense when taking the whole universe as being the "observer"...

rswail4• 1 year ago

People will be gathering at the Restaurant At The End Of the Universe with Douglas Adams as the host.

chasing• 1 year ago

Probably on a Thursday. I never could get the hang of Thursdays.

octocop• 1 year ago

the term "sooner" in this case is, you know, relative

jmclnx• 1 year ago

Because the researchers were at it anyway, they also calculated how long it takes for the moon and a human to evaporate via Hawking-like radiation. That's 10^90 years.

Well I can predict the next trend, launching very rich people's body into space so it will last 10^90 years :)

pixl975• 1 year ago

Depends what you mean by last.

Over periods of time that long it's much more likely you'll run into some other object, say fall into a gravity well or something like that.

Even if you don't, pure erosion from neutral hydrogen and space dust will have disintegrated your capsule long before then.

JohnMakin2• 1 year ago

Bad news for Boltzmann brains

matheusd• 1 year ago

Is it though? It is my understanding that the quantum fluctuations that give rise to BBs will still exist, even after (and specially after) the evaporation of black holes (perhaps assuming no Big Rip).

JohnMakin2• 1 year ago

It's just a joke but the average number of years for a spontaneous quantum fluctuation to produce a boltzmann brain was calculated at something like 10^500 years. You're right that the processes involved would still remain barring some kind of big rip event.

x1000• 1 year ago

Not a physicist, but I see it this way too. My understanding of Boltzmann brains is that they are a theoretical consequence of infinite time and space in a universe with random quantum fluctuations. And that those random fluctuations would still be present in an otherwise empty universe. So then this article has no bearing on the Boltzmann brain thought experiment or its ramifications.

layer82• 1 year ago

They may not actually happen: https://arxiv.org/abs/1505.02780

red75prime• 1 year ago

Why they should be limited to our universe?

dan_can_code• 1 year ago

Damn. That ruins my retirement plans

bdangubic• 1 year ago

just in time for your 401k to recover :)

KingOfCoders• 1 year ago

One of my favorite Wikipedia pages

https://en.wikipedia.org/wiki/Timeline_of_the_far_future

lattalayta• 1 year ago

In video form: https://www.youtube.com/watch?v=uD4izuDMUQA

tarsius• 1 year ago

For dramatic effect, my monitor turned off right after "By this point, distant galaxies and starts are receding so fast that their light has become undetectable."

rwoerz• 1 year ago

My favourite sleep aid video.

alexey-salmin• 1 year ago

There's also this lovely musical video https://www.youtube.com/watch?v=FMJNta-okRw

The "no more strength, no way out" part kills me every time I watch it.

butlike4• 1 year ago

Seems like unproven mumbo jumbo after about the halfway point

VagabundoP2• 1 year ago

Here's my favorite youtube version of this:

https://youtu.be/uD4izuDMUQA

thih92• 1 year ago

in 10k years (…) the average length of a solar day will be 1⁄30 of an SI second longer than it is today.

Looks like a new test case scenario for libraries that handle time/date.

Timon3• 1 year ago

Am I misreading something, or isn't that already in 1,000 years?

timewizard• 1 year ago

Insertion of a leap second every month.

AnotherGoodName• 1 year ago

Well at least the datetime library would be a perfectly reasonable place to handle leap seconds. The place that outputs the timestamp to a human readable format wouldn’t at all be that hard pressed to add a second when printing out the local time with timezone considered. It really wouldn’t add that much complexity.

Could you imagine if anyone was stupid enough to think the right place to handle such a thing was the internal counter of seconds rather than the datetime library though? Ha! That’d be ridiculous right! Imagine all the bugs if someone put something that’s only relevant to local timezone time printing there! It’d cause so many unexpected bugs!

Gibbon1• 1 year ago

At 10^78 years we could use 512 bit time stamps and be safe from overflow and measure all the way down to Planck time.

joquarky4• 1 year ago

Time is so /weird/ that I don't know how computers will ever wrangle it comprehensively.

Just consider the weird but valid scenario in relativity where A can occur before B, B before C, and C before A. I'm not sure how you would wrangle something like that in a data format.

slicktux• 1 year ago

Great wiki page! It even mentions Boltzmann Brains! “ This infinite future could allow for the occurrence of massively improbable events, such as the formation of Boltzmann brains.”

platz• 1 year ago

Boltzmann Brains usually mean something is wrong in your cosmology

paulpauper• 1 year ago

So given these finding, that page will need to be overhauled a lot

burnt-resistor4• 1 year ago

To survive beyond 1 Gy from now, life will need to move underground where the water is and hopefully much cooler than the eventual surface. Also, such life may/will become necessary to relocate to Mars, hopefully taking resources with them. (I don't say "us" because of likely dramatic evolution.)

zmgsabst• 1 year ago

1 Gy ago, life wasn’t multicellular.

I don’t think we have the ability to meaningfully predict such scales.

thombat• 1 year ago

The only reason that the subsurface rock is cooler than magma is being able to conduct heat through to a cooler surface. When that surface becomes exterminatingly hot and remains so for a while the subsurface will be heating up too. Since the sun is estimated to remain a red giant for about one Gy it will become hotter than the surface.

Timwi• 1 year ago

At that scale of time, it's not implausible that we have the technology to relocate Earth itself by then (e.g. increase its orbit).

evtothedev• 1 year ago

I feel like you could build an entire meditation practice around reading this article.

azemetre• 1 year ago

That or existential dread.

NKosmatos• 1 year ago

It pairs well with https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe

zem• 1 year ago

and with http://www.geoffreylandis.com/infinite.htp

grues-dinner• 1 year ago

If Reid Malenfant or Jim Bolder aren't involved, this isn't the deep time future I'm interested in.

mediumsmart• 1 year ago

so many years - and how many miles?

belter• 1 year ago

Did Broadcom acquire this Universe?

IamLoading• 1 year ago

If humans end up existing at 10^77 years. You would hope and imagine that they would be prepared for the decay?

recursive2• 1 year ago

Well, that's only 10% of the way there, so they'd still have most of the time left.

hinkley10• 1 year ago

Let the grandkids worry about it. Now would you be a pal and hand me another another atomic mimosa?

hathym• 1 year ago

with what's going on, not sure if human will exist in the next 10 years

foobarkey• 1 year ago

My pet theory: all atoms decay back to hydrogen given enough time, gravity pulls them together, stars form, the universe is one big loop that self resets :)

ewzimm• 1 year ago

You're in good company. Something similar, minus the hydrogen phase, is proposed by Roger Penrose: https://en.wikipedia.org/wiki/Cycles_of_Time

6gvONxR4sf7o• 1 year ago

I went to a talk of his on CCC ages ago, and it was such a fascinating combination of geometry, causality, and asymptotics. I have absolutely no clue whether it's reasonable physically, but independent of that, it's just a really elegant fusion of topics in a fun to think about way. Worth a read for anyone who just appreciates elegant new ways of combining mathematical structures.

mensetmanusman4• 1 year ago

Apparently time ceases when absolutely all mass is gone, because mass is required for a clock.

This of course requires the decay of protons.

HideousKojima• 1 year ago

My pet theory:

The Big Bang happened at the "north pole" of spacetime. Eventually all matter and energy will reach the "south pole" and recombine. The Big Crunch theory will never die!

vlovich1232• 1 year ago

The big bang happened at the center of the universe and every point of space is the center of the universe at all times. You could argue that the center of spacetime is definitionally the Big Bang since that’s when time is believed to have started to exist in the first place but we don’t have a good grasp of how to define the center of a 4D physical structure where one dimension is time which doesn’t seem to really act like the other dimensions.

layer82• 1 year ago

The evidence about the accelerating expansion of the universe would seem to contradict that theory.

vlovich1232• 1 year ago

Not necessarily.

A) We don’t know if all derivatives are >= 0. e.g. if the jerk rate is < 0, then you’d expect contraction eventually. Similarly, if the derivative of the jerk rate is < 0 & so on. So even accelerating expansion could eventually lead to contraction.

B) We don’t have a lot of very highly compelling evidence that the universe is actually accelerating (at least nowhere like we do for the Big Bang). For example, alternate models have proposed that our apparent perception of the expansion is simply as a result of the effect of non-uniform gravity throughout the universe & that the vaccuum of space between galaxies has even less time dilation and that’s what make it look like things are expanding.

In other words, I’d put the model of a permanently expanding universe as less likely to actually match reality.

chasil• 1 year ago

The proton itself that forms the hydrogen atom might decay (we don't know yet; we do know that neutrons decay after 15 minutes).

https://en.wikipedia.org/wiki/Proton_decay

hinkley10• 1 year ago

Neutron decay is one of those things that I forgot between college physics classes and today and it was sort of surprising to rediscover it.

We also know that electrons eventually decay but it's something like 10^26 years, which is long enough to say that probably not many electrons in the solar system have decayed since the universe was born but the universe is really stupidly big, so it absolute numbers that could still be a lot of dead electrons. Maybe a solar system's worth.

Surprisingly there is no wikipedia page for this. Just rando articles.

butlike4• 1 year ago

BRB, setting my pomodoro timers to be 15min instead of 20min to account for my brains neutron decay eating up all my inspiration

kgwgk• 1 year ago

Iron is the most stable atomic nucleus (at least if we don’t consider Nickel-62).

ThrowawayTestr• 1 year ago

Heat death is just so depressing.

burnt-resistor4• 1 year ago

Maybe we should siphon off hydrogen and helium from the Sun for storage elsewhere in the Solar System to reduce the burn rate to prolong the usable lifetime of its fuel? And build a Dyson sphere. ;D

amelius• 1 year ago

But will the sequence of events be exactly the same in each loop iteration?

cryptonector• 1 year ago

Well... black holes don't evaporate into hydrogen, but into light and various light particles. The hydrogen left over at the heat death will necessarily be too diffuse due to the expansion of the universe. It can't light up again like that. Perhaps the computer in The Last Question was hallucinating at the end.

A_D_E_P_T3• 1 year ago

It's nonsense.

See this comment on their previous paper: https://arxiv.org/abs/2306.07628

The authors of the comment show that the "gravitational pair-production" rate used in the work in OP comes from truncating the covariant heat-kernel (proper-time) expansion of the one-loop effective action at second order in curvature, an approximation that is valid only in weak-field regions where all curvature invariants satisfy |R| · ℓ² ≪ 1 (where ℓ is the Compton wavelength). When that same expression is pushed into the high-curvature interior of a neutron star -- where the inequalities fail by many orders of magnitude -- the series is no longer asymptotic and its early terms generate a spurious imaginary part. Because the paper's entire mass-loss mechanism and lifetime bound follow from that uncontrolled imaginary term, its conclusions collapse.

Simply put, it doesn't even correspond to known experiments. It's entirely driven by a narrow artefact and has no physical basis.

PaulHoule• 1 year ago

The authors wrote a reply to that comment

https://arxiv.org/pdf/2308.12326

I think about how some relativists think you could see a Hawking Radiation like effect if you're accelerating

https://en.wikipedia.org/wiki/Unruh_effect

although the idealized case of endless acceleration implies a certain kind of horizon

https://en.wikipedia.org/wiki/Rindler_coordinates

maybe the horizon doesn't matter much,.

A_D_E_P_T3• 1 year ago

There's a lot wrong with that reply -- it mostly just shifts the goalposts without answering the central objections raised in the comment.

Much of the reply revolves around whether the mixed invariant G=E⋅B appears at leading or higher order in the QED Schwinger result. But the comment's critique used the constant-field Schwinger problem only as a check that the authors' master formula fails against a case with an exact answer; the real complaint is that the same failure occurs for curved-spacetime examples where the exact result is known to vanish. Debating G is fine, but you can't ignore the gravitational case either.

The reply repeatedly says the comment is "outside the realm of applicability" of the formula -- as though that were the comment's fault! But if the formula cannot survive the very checks the authors themselves hold up (Schwinger with B≠0, Ricci-flat space), the burden is on the authors to (severely) restrict their own claims, not on critics to ignore the failure modes.

LegionMammal978• 1 year ago

Naively speaking, these predictions seem like they should be very sensitive to all sorts of effects, some better understood than others. It's odd how many commenters here treat headlines like these as settled fact, instead of one team's calculations based on assumptions that may be wildly off.

zero_bias6• 1 year ago

Very strange prediction indeed, the object need an event horizon for hawking radiation to occur

lawlessone• 1 year ago

i'll have to move that meeting forward.

jeff_carr• 1 year ago

/remindme in 10^60 years

wwilim• 1 year ago

Better get around to painting those Warhammer minis soon

hinkley10• 1 year ago

I gotta start working on my reading backlog. Luckily I already returned all my library books.

tsumnia• 1 year ago

Glad to see my Collapsing Universe Theory is starting to happen

1970-01-01• 1 year ago

Upgrade to Universe 2.0 before our EOL date of 10⁷⁸ and receive a free 10⁸ month trial of Universe+ with cosmic karma monitoring and additional features such as dark mode.

usui• 1 year ago

I... I thought we already had dark mode..

kridsdale12• 1 year ago

No. The CMBR of the current universe gives a nice comforting grey. Upgrade today for VantaBlack cosmos, guaranteed no EM at all!

JRCharney• 1 year ago

I wish the universe would give me the option not to restart and apply this update right in the middle of a project! It's not like I was working on something or had my browser tabs the way that I like them.

butlike4• 1 year ago

Will I need a TPM module though?

speckx• 1 year ago

Time to dig into that game backlog on Steam.

charlieyu1• 1 year ago

It's the first time I see unicode exponent numbers actually get used

foreigner2• 1 year ago

My HN reader displays this topic as "Universe expected to decay in 10 years, much sooner than previously thought".

And it's not wrong, that _is_ much sooner than previously thought!

munificent• 1 year ago

I mean, it's already decaying. So it will be decaying in 10 years too.

It's really a question of when it will stop decaying.

Bluestein• 1 year ago

There go my vacations! :)

nkrisc• 1 year ago

It used to be decaying. It's still decaying, but it used to, too.

shikon7• 1 year ago

If there is nobody left to observe when it stops decaying, will it ever stop decaying?

Traubenfuchs• 1 year ago

Complete/Finish might be clearer.

isk517• 1 year ago

Considering 10^1100 years was the previously postulated time to decay then, assuming the Netherlands Research School for Astronomy is correct in their 10^78 years calculation, 10 years is still significantly closer to the correct date.

mensetmanusman4• 1 year ago

What’s it called when the exponent is off by an order of magnitude, ha..

mhh__• 1 year ago

If these trends continue.... Ayyyy

ianburrell• 1 year ago

Firefox displays 10^78 with boxes for superscript. Chrome doesn't have any problem.

burnt-resistor4• 1 year ago

It could either be your fonts and/or your particular platform. I've seen this sort of thing before elsewhere, I think on Windows with certain fonts IIRC. I opened it on Firefox 138.0.1 on aarch64 for mac and there weren't any artifacts.

deepsun• 1 year ago

I'm on Firefox -- no problems. Both on Android and Linux.

kulahan• 1 year ago

Displayed just fine in Brave as well, for the curious.

kiwijamo• 1 year ago

Firefox on Android mobile displays it fine. Probably an OS level font issue.

joshdavham• 1 year ago

My HN reader [...]

What reader do you use? I've only ever used vanilla HN.

Lord_Zero• 1 year ago

I use harmonic

foreigner2• 1 year ago

Hews 2 on Android. I have a Pixel 6. Generally I'm satisfied with Hews 2, it just rendered this particular title in a funny way.

moomin• 1 year ago

Good time to take out a 30-year mortgage.

graypegg• 1 year ago

Damn... got to adjust the roadmap. Universe heat death milestone just got moved up.

seydor• 1 year ago

Bad news for my proton decay stocks

feverzsj• 1 year ago

That's really bad news for immortals.

hinkley10• 1 year ago

Better make friends with the creation immortals so you get invited to their parties.

cozzyd• 1 year ago

good news, we'll never need more than a 512 bit time_t

divbzero• 1 year ago

Relative to that time scale we are still, at ~10¹⁰ years, in the opening moments of the universe.

hinkley10• 1 year ago

If an age of the universe passed for every year the universe has already existed, we'd still have some time left at the end.

unzadunza• 1 year ago

According to The End of Everything (https://www.goodreads.com/book/show/52767659-the-end-of-ever...) decay is only one of the ways it all ends. Unfortunately most (all?) the other ways happen way earlier.

fuzzer371• 1 year ago

So... Who cares. No one is going to be around even 10^3 years from now. It doesn't help anyone to know, and there's nothing we can do about it.

the__alchemist• 1 year ago

I am suspicious this attitude is responsible for much personal and environmental destruction. I wonder how we can remove it from humanity; it is one of the most dangerous pervasive mindsets for our, and the biosphere's survival.

JesseTG• 1 year ago

If anyone here happens to be immortal, how will you plan around this?

nottorp2• 1 year ago

In the long run we're all dead aren't we?

vasco• 1 year ago

And taxes

nottorp2• 1 year ago

I believe most jurisdictions stop taxing you when you're dead.

thebruce87m• 1 year ago

You were dead before. On average you’ve been dead the whole time.

deadbabe• 1 year ago

When we’re dead, I know we don’t feel anything, but when the universe also becomes dead I wonder if we’ll not feel anything to a degree that we didn’t even know possible, a death beyond death, if that makes sense. It’s like not only are we dead and gone, but our entire life is gone so thoroughly that it’s like it never even happened, and if it never even happened, what the hell is this moment we experience now? Just a passing illusion as a universe explodes?

Workaccount2• 1 year ago

That is about within a factor of 1000 of the number of atoms in the universe. So divide the universe into 1000 compartments of equal atom count, and there is about 1 year left for each atom in there.

To put this in perspective, a drop of water is about 1 trillion groups of 100 billion atoms (or 100 sextillion atoms).

So, we got some time left.

JadeNB2• 1 year ago

That is about within a factor of 1000 of the number of atoms in the universe. So divide the universe into 1000 compartments of equal atom count, and there is about 1 year left for each atom in there.

This sounds tedious, but it might help to realize you can just gather all the atoms together first, and then count only every 1000th one.

fallingknife• 1 year ago

I was thinking that since apparently Hawking radiation applies to all objects (I thought it was just black holes), maybe it would be interesting to try to actually observe it on the moon. But then I ran the numbers and, if the authors are correct, the moon is losing about 1 electron mass to Hawking radiation every 10^37 years!

BlandDuck• 1 year ago

"Estimate of the remaining time before universe decays expected to be revised 10^76 times before its finally over"

(conservatively assuming the estimate will be revised about once every hundred years as we learn more).

jpease• 1 year ago

Accepting table reservations now, you won’t want to miss this.

hinkley10• 1 year ago

Sorry I'm busy that day. Can we schedule for the following... oh. How about the previous Tuesday?

Vasniktel• 1 year ago

OMG, the economy

tgma• 1 year ago

Could be just one accidental Ctrl+C away.

kqr2• 1 year ago

TLDR: Hawking radiation can cause things besides black holes to evaporate.

  Man and moon: 10^90 years

Because the researchers were at it anyway, they also calculated how long it takes for the moon and a human to evaporate via Hawking-like radiation. That's 10^90 years. Of course, the researchers subtly note, there are other processes that may cause humans and the moon to disappear faster than calculated.

wpollock• 1 year ago

Diets not working for you? Try the new Hawking radiation weigh loss plan! Guaranteed to lose half your mass in only 10^45 years!

beau_g• 1 year ago

Bad news for Bryan Johnson, he will have to adjust some of his long term plans

paulmooreparks• 1 year ago

In 1975, physicist Stephen Hawking postulated that contrary to the theory of relativity, particles and radiation could escape from a black hole. At the edge of a black hole, two temporary particles can form, and before they merge, one particle is sucked into the black hole and the other particle escapes.

Hasn't this explanation been discredited for a while?

https://bigthink.com/starts-with-a-bang/hawking-radiation-bl...

Black holes are not decaying because there’s an infalling virtual particle carrying negative energy; that’s another fantasy devised by Hawking to “save” his insufficient analogy. Instead, black holes are decaying, and losing mass over time, because the energy emitted by this Hawking radiation is slowly reducing the curvature of space in that region. Once enough time passes, and that duration ranges from approximately 10^68 to 10^103 years for black holes of realistic masses, these black holes will have evaporated entirely.

https://bigthink.com/starts-with-a-bang/hawking-radiation-re...

zero_bias6• 1 year ago

Both explanations are merely simplifications of a truly complex phenomenon, so both are valid. Reducing space-time curvature is equivalent to the absorption of a virtual particle with negative energy

zombot• 1 year ago

Darn, I'll have to cancel my party plans for that weekend.

weregiraffe• 1 year ago

Oh no, all my plans for the 10^100 year celebration party!

zero_bias6• 1 year ago

Evaporation isn’t as bad as false vacuum decay. I thought the news would be about that. Fast vacuum decay would be much worse, as civilization can withstand matter loss but not the ultimate false vacuum decay

haarolean• 1 year ago

ultimate

Who knows? Maybe when and if that happens, civilizations will be advanced enough to try to reverse this: manipulating the local Higgs field, pocket universes, and counter-decay waves

zero_bias6• 1 year ago

The problem is that false vacuum decay spreads at the speed of light, leaving no time for preparation, and the laws of physics would be completely altered without warning. Perhaps future civilizations could resist it, but with our current understanding, it’s a doomsday in a blink of an eye

ximm• 1 year ago

Damn, I had planned to go shopping on that day!

lvncelot• 1 year ago

I always assumed that an event horizon was a necessary condition for hawking radiation (or the Unruh effect, for inertial frames). Interesting that this apparently isn't the case, and the authors rather predict all objects with mass to have this property.

gigatexal• 1 year ago

Other gravitational bodies radiating via hawking radiation is a bold claim. Has this work been validated? Challenged? Confirmed?

nomercy400• 1 year ago

I wonder how you decide to measure things in years on this scale. I mean, in about 10^10 years, the whole concept of a 'year' will stop to exist. What will you do then?

I would expect something like 'tera-seconds', or something related to a cosmological constant but at cosmological scale, like the time to decay hydrogen or number of caesium vibrations for example, but then scaled at AU scale. A value not related to time or space.

mr_mitm3• 1 year ago

A year is defined in multiples of caesium vibrations. Not originally, obviously, but in this context it is. You cannot nearly measure any of these time periods precisely enough that any of this matters anyway.

scotty79• 1 year ago

This is as removed from any observation and predictive utility as counting angels on the head of a pin.

odyssey7• 1 year ago

There’s no way that we happen to exist in just the first 10^78 years of eternity.

tomcam• 1 year ago

Now I feel like an idiot for paying off my house

nopelynopington2• 1 year ago

But I just bought a house in the universe!

revskill• 1 year ago

Why ?

nopelynopington2• 1 year ago

Well I didn't know it was going to decay so bloody soon

xunil2ycom• 1 year ago

I better update my will.

rendall• 1 year ago

I don't know why 10^78 unsettles me more than 10^1100 does.

keepamovin• 1 year ago

Aw fuck!!

I was looking forward to curing a few more deaths and bringin the Bitchun Society to yet more barbarian tribes in the outer reaches. I wonder if all my whuffie will last that long? I really don't want to deadhead so hopefully there's plenty more interesting things to do in the tail end. Hahaha :)

Universe expected to decay in 10⁷⁸ years, much sooner than previously thought

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