Hacker News new | past | comments | ask | show | jobs | submit login
Timeline of the Far Future (wikipedia.org)
168 points by nixass on May 17, 2020 | hide | past | favorite | 112 comments

Related ideas that seem kind of obvious but haven't seen them mentioned anywhere yet:

1. We live in the most interesting 200 year period of Earth so far in its 4.5B year history. The rate of progress has never been so high, one notable example of why this period is special and unprecedented is that it's the first time humans or any species has visited the Moon. It's quite a mind-blowing coincidence.

2. Human history will probably look like a sigmoid curve - long period of stagnation followed by rapid progress followed by a long period of stagnation. We were born into a very short period of something like 1000 years with the highest rate of progress. After that, we'll gradually enter an equilibrium in which things won't change much (or a period in which history will just repeat with minor variations). The year 300,000 will look similar to year 301,000 - despite being separated by a millennium - this is unthinkable at this point in time. You can't keep inventing novel technology and art at current pace for a million years. Has there been any debate about how this long period of equilibrium could look like?

Progress is already winding down. Deisel engines, airplanes, splitting the atom, computing, antibiotics...all huge but not recent developments. With the exception of the internet, what have we done recently? Maybe human genome project? Renewable energy? Practical neural networks?

Now, we've spent the last few decades refining these ideas, but we're hitting some peaks. How much more efficient can we make an engine? Can we really get off fossil fuels when they're used for everything ranging from fuels to plastics to fertilizers. We've been working on solving cancer for decades and haven't made much progress. We're still nowhere near widespread nuclear fusion and have abandoned nuclear technologies almost altogether outside of the US Navy. Computing is all about shrinking things, but we're starting to hit walls and practical quantum computing still appears to be a distant dream. AI is still nothing like we'd hoped it would be. We're no closer to understanding the brain in a way that would lead to an AGI. More physics research occurs in a matter of months than a decade at the turn of the century. Have we reconciled relativity and quantum mechanics yet? Are we any closer to GUT? I suppose there have been some advanced in our understanding of the universe due to the new instruments we've put into orbit. Nanotechnology is still essentially science fiction outside of some nanotube devices.

> genome project? Renewable energy? Practical neural networks?

Isn't that enough? (And you left out quantum computing. Smart phones. GPS. Composite materials. Autonomous vehicles. I could go on.)

Not to mention a whole new JavaScript framework every other week.

Laughed out loud at this. Nailed it.

Humans: A short lived species that produced some interesting grammars.

Yes the planet got destroyed. But for a beautiful moment in time we figured out how to center HTML elements both horizontally AND vertically!

Indeed. Half the things on this list happened after 2010.


I wrote it in 2016. I should make a new list.

I did not leave out quantum computing which is nowhere near practical right now and maybe never will be.

GPS is a good technology. Autonomous vehicles work fine for the 90% use case, but will likely never reach that last 10%.

Quantum computers and autonomous vehicles are more promise than fact, otherwise you might want to throw fusion energy in there as well.

> The year 300,000 will look similar to year 301,000 - despite being separated by a millennium - this is unthinkable at this point in time.

The Fermi Paradox is rooted in the idea that if alien intelligences were doing things that we could recognize, we should have seen them by now.

Perhaps they do exist, but have progressed so deeply into the unthinkable that we can't even.

Perhaps we will as well.

You may have seen this resolution to the Fermi Paradox, but if not I thought I'd post it: https://arxiv.org/abs/1806.02404

"The Fermi paradox is the conflict between an expectation of a high {\em ex ante} probability of intelligent life elsewhere in the universe and the apparently lifeless universe we in fact observe. The expectation that the universe should be teeming with intelligent life is linked to models like the Drake equation, which suggest that even if the probability of intelligent life developing at a given site is small, the sheer multitude of possible sites should nonetheless yield a large number of potentially observable civilizations. We show that this conflict arises from the use of Drake-like equations, which implicitly assume certainty regarding highly uncertain parameters. We examine these parameters, incorporating models of chemical and genetic transitions on paths to the origin of life, and show that extant scientific knowledge corresponds to uncertainties that span multiple orders of magnitude. This makes a stark difference. When the model is recast to represent realistic distributions of uncertainty, we find a substantial {\em ex ante} probability of there being no other intelligent life in our observable universe, and thus that there should be little surprise when we fail to detect any signs of it. This result dissolves the Fermi paradox, and in doing so removes any need to invoke speculative mechanisms by which civilizations would inevitably fail to have observable effects upon the universe."

Another explanation for the Fermi paradox I had heard, which certainly is less rigorous than the linked article but easier to understand is:

The root of the paradox is that with so many planets in the universe (in the order of 10^24), there must be more life in the universe. But even with this unbelievably large number of potential planets, if creation of intelligent life on a planet requires only 24 independent parameters to be favourable, and each of them are favourable with a probability of 10%, then we should expect intelligent life in just one planet: ours.

There is a slim chance that we are the first ones with sentience ever. That would totally explain Fermi paradox.

Why not? We are definitely the first on this planet, and we don't try to dispute this fact using probability measurements.

The planet has an observable fossil record, whereas extra-solar heavenly bodies are still largely inscrutable.

Of course. But if we didn't have this evidence, the logic of the Fermi paradox would lead to conclusions that we just can't be the first ones because the probability for it is so impossibly low.

Low probability compared to what though? This makes less sense to me on closer inspection. I agree that there may be some meaningful observation in there, but it's hard to even figure out what the paradox or observation is.

An individual (or hive mind, whatever) living in the year 300,000 AD may very much dispute the claim that progress has stagnated. It's entirely possible that civilization has continued an exponential expansion (within limits) from now until then. As such, history is one continued exponential.

Provided that this civilization still is not bumping against the thermodynamic computational limits of space by several orders of magnitude, then the Fermi paradox is still a paradox.

That's how an exponential works, every point sees itself as a privileged point, right before it increases massively.

Right, on one hand I feel blessed to be alive, as with all of you, in what is certainly the most important time in human history. Beside the effects of every technological advancement which currently exists at a transitional period, the greatest moment of birth and rebirth in history could be upon us, thanks to the Holocene extinction event we have triggered. Whether or not we capitalize upon our special place in history remains to be seen.

But I also know I'm missing out on the true space-faring age, the Humanitarian Revolution, the Quantum Age where we begin to fully exploit the laws of QM, the Last World War, extra-solar colonization, etc.

Eventually, if we don't kill or exhaust ourselves with impatience, technology will be solved with respect to providing enough energy and resources for every conceivable human. Then, the real challenge begins. Providing for a population beyond its basic needs becomes an entirely political affair. We may be arrested on the lower levels of Maslow's Hierarchy of Needs for quite some time.

Will humanity observe a similar exponential advancement in humanitarianism as it has with technology? How important is humanitarianism to Fermi's Paradox and the Drake Equation?

Enough energy for every human individual is already a solved problem, although not necessarily sustainably. It's not even economically prohibitive to switch to sustainable options, there's just insufficient incentives at this time. The great travesty is that, when incentives are put in place, the Holocene damage will be difficult to stop and impossible to reverse.

Our own survival chances seem to be a fraction not close to unity, but not close to 0 either. Give it 75% to be optimistic. After that, robotic seed space ships could be a buffer to protect from subsequent cataclysms. That does nothing to answer the questions of Fermi's paradox, unless you low-ball to 1.0e-6% chance of survival. Doomsayers guessing such a number are not generally taken seriously.

Looking elsewhere, we have almost unlimited wiggle room in the chance of photosynthesis evolving. Traits that evolved multiple times in Earth's history are inadmissible to this discussion, but several critical traits evolved only once. Fertile but desolate planets are, based on current science, probably abundant. As a typical reasonable human, this is a perfectly sufficient speculative answer.

As I understand your remarks, you basically believe what Fukuyama stated in The End of History and the Last Man. This has largely been proved to be wrong on many counts and even Fukuyama himself disavowed many of his earlier ideas.

Humanity is currently facing, and is going to face in the near future, multiple very hard challenges, which are unlikely to be solved purely by technology, the most serious of which is the changing climate.

The more likely future, in my opinion, looks like a regress to an earlier state of "progress" with long-term fluctuations as the changes manifest themselves with various degrees of severity.

> We live in the most interesting 200 year period of Earth so far in its 4.5B year history.

People have been saying this for centuries now. And they will probably continue to do so in the future. Our rate of progress looks so high because we are living in it. Cut to another two hundred years and 2000 will look just like 1800.

For the last few centuries maybe. Your underestimating how utterly anomalous has been the last about 200 years. There's a clear contrast between that and all prior 200 year periods. The idea of progress is relatively recent, 2 thousands years ago it basically didn't exist (from the book Sapiens).

From where I am standing, 1800 doesn't look anything like 1600.

This is the optimistic scenario!

There's no shortage of reasons why there might not be humans at all in 300,000 AD.

Progress matters, but not as much as one would think. On the grand scheme of things, it's grossly overrated. When a human is brought to this world, everything is new to him or her, whether it's seeing a bird in the sky, meeting people, creating a family, growing crops or reading a story to a child. There is no reason to believe that in a lifetime a person would be able to enjoy all of the ever growing number of things that are available to experience in any meaningful way.

The length of a lifetime itself is subject to progress, and with hope it'll eventually grow longer. And arguably, it's only due to progress that we now have more things to experience than we have time for; it wasn't true for vast majority of human history.

For a more detailed description of the future, see Stapledon's Last and First Men.

> we'll gradually enter an equilibrium in which things won't change much


> The year 300,000 will look similar to year 301,000


> You can't keep inventing novel technology and art at current pace for a million years.

Will we run out of technologies to discover and art to create? Why? When?

We live in the most interesting 200 year period of Earth so far in its 4.5B year history

Even granting you the anthropocentric premise, the idea that the last 200 years are more interesting than any other similar period is not at all obvious.

The progress in the last 200 years is completely incomparable with anything prior to that. Per the book Sapiens, the idea of progress is relatively new, people used to believe that things would stay the same or decline.

The progress in the last 200 years is completely incomparable with anything prior to that.

Again, rather an unobvious claim. A greater leap than the Industrial Revolution, the Renaissance, the budding of Western Civilisation with the Greeks?

Perhaps it is, but unless you have a link to proof of this, it's best not to speak in such dogmatic terms, and accept that this is just a view you hold.

Human history will probably look like a sudden, massive, and apparently-inexplicable upward spike in global atmospheric CO2 content accompanied by mass extinction.

> After that, we'll gradually enter an equilibrium in which things won't change much (or a period in which history will just repeat with minor variations).

Not necessarily: https://en.wikipedia.org/wiki/Technological_singularity

Not even GAI can beat known physics unless new physics come into play.

I do not see how physics prevents huge changes in our technology. We cannot say we know almost everything about nature at all.

Examples: room temperature superconductivity, efficient solar cells, quantum computer and much more.

>You can't keep inventing novel technology and art at current pace for a million years.

Or can you?

Even the sigmoid is a somewhat optimistic picture. Another possibility is a bell curve, where due to resource depletion we eventually end up back near where we started. It's interesting to imagine how over time the scientific knowledge we've obtained with our particle accelerators and space telescopes and electron microscopes would decay in the absence of high technology. If it has been 800 years since anyone has directly observed a Higgs particle or a molecule of DNA, what reason would there be to remember accurately what it was, or even to remember it at all? People of the future might end up thinking that the Higgs was a deity worshipped by us people of the past, given all of our references to the "God particle".

You assume we will lose all record of our discoveries so far, which has some precedence with Roman sewage treatment being forgotten, but we are much better at keeping records and we have too many artefacts from this period that will naturally prompt curiosity to future generations.

Even if some unforseen solar event disables our electronics for a millennia, and we devolve into infighting, the winners will still be those with the technological superiority, mechanically gas-powered or otherwise.

The only threat I can envision is a wild asteroid, but then it's game over for all of us.

Not being facetious, but how do you define progress?

I mostly mean technological progress, I don't have a precise definition.

"You can't invent", AI might.

I don’t know what about “200 year period” is particularly exciting. For us humans, maybe... but the 4.5 billion year time-span suggests you’re taking a wider view. From the planet’s point of view there’s just a mass extinction going on whilst the anthropogenic climate change gets into full swing. It’s neither exciting nor unprecedented.

Mandatory Isaar Arthur links:

- Civilizations at the End of Time: Iron Stars [1]

- Civilizations at the End of Time: Black Hole Farming [2]

- Boltzman Brains and the Anthropic Principle [3] [4]

[1]: https://www.youtube.com/watch?v=Pld8wTa16Jk&t=1080s

[2]: https://www.youtube.com/watch?v=Qam5BkXIEhQ&t=10s

[3]: https://www.youtube.com/watch?v=9UfQb_-XAuY

[4]: https://www.youtube.com/watch?v=GrK9EaQRp2I

Fun fact: this link has already been submitted 27x on HN


Best to fish for the nontrivial threads:


Thanks dang! I did know the comments command


Reminds me of how the Graphing Calculator Story has been submitted around a similar number of times. I don’t mind it.


I thought I had seen this posted here before. Regardless I re-read the entire thing every time it is posted.

Me too. And every time I get to oceans boiling out I get somewhat depressed and worried for my children. No kidding.

I have often thought about what it would be like in the far, far future. After the age of baryons comes to an end, we would also see an end to structure: you cannot build anything out of leptons larger than a positron and electron orbiting one another, delicately, at a distance. No chains, no three-way bonds or glorious carbon four-way bonds, just a froth of electrons, positrons, and variously-flavred neutrinos and anti-neutrinos.

If the Big Rip were to happen, one might imagine civilizations forming around the event horizons of black holes ("dead stars still burn") fizzing out Hawking radiation, getting ever closer to avoid the Big Rip, a controlled fall designed to balance against the stretching of space while harvesting what you could get from Hawking radiation. I've seen projections, sketches, really, of computation that involved states only changing as energy became free, and so these civilizations would be almost frozen in amber to outsiders but ticking along from their vantage point, up until the black holes' "temperature" drops too far below the ambient themal bath. The decay gets faster and faster as the curvature of the event horizon increases, so that civilization's end would have an incredible speedup right before the black hole itself evaporated.

The last bit you mention reminded me a lot of The Physics of Immortality (Frank J. Tipler, 1994) which I first read in when I was thirteen or fourteen years old. This was before it had been proven that the cosmological constant existed and was positive, so he was musing about how a quantum computer instantiated in the final moments of a Big Crunch would have asymptotically infinite processing power and could simulate everybody who ever lived (and everybody who didn’t actually live, but could have, too).

An electron-positron bound system decays in under a nanosecond:



> If the Big Rip were to happen

That's a really big If. Since we're well into the realm of fields-on-General Relativity in this paragraph, you'd have to add one or more additional fields to provide a "fifth force" (thus, in these sorts of approaches quintessence) to overcome the other known fundamental interactions among the other fields of the Standard Model, of which there are more than three. The fourth, gravitation, is poorly modelled as a force when we are dealing with clearly relativistic gravitation, as is the case with [a] a black hole or [b] the appearance of lots of empty space around all sources of gravitation.

Nobody has yet made a consistent interacting model of quintessence, where the interactions reflect those of the Standard Model or gravitation, so nobody can really do anything but handwave about what extra interactions from "fifth force" fields would do with respect to e.g. the Higgs mechanism. Additionally, I say fields because when one gets into the weeds of formalizing a quintessence field theory one ends up with self-interactions -- additional interactions in the new parts added to the Standard Model.

Quintessence theories are interesting to probe the structure of theories (mostly quantum field theories in curved spacetime), but are really not interesting for studying the physically observed cosmos with our present level of understanding of the Hubble parameter, or the mechanisms that generate the "true" metric.

Without these extra interactions, there is good reason to believe that there won't be a big rip: at smaller scales, stars, planets, people, pocket computers, molecules, atoms, are in no danger of being locally disturbed by the metric expansion of inter-galaxy-cluster space.

> around the event horizons of black holes ("dead stars still burn") fizzing out Hawking radiation

Hawking radiation appears surprisingly far from the event horizon, rather than near it[1] and for a black hole whose near-horizon exterior is gentle enough an environment to support any sort of structure (space-stations, say, and especially ones that can support life as we know it) the Hawking radiation is virtually always going to be colder than the cosmic microwave background measured in local coordinates by a near-horizon observer. If you want to be fanciful, you are much better off erecting a very large scaffold around a very large black hole, and then "mine" it with a bucket. [2]

- --

[1] Unruh [2007], http://inspirehep.net/record/775859?ln=en from which the DOI link will take you to the cc-by-nc-sa pdf.

[2] Brown [2012], PRL preprint https://arxiv.org/abs/1207.3342 has a quick overview and decent bibliography notably Gibbons in [11].

I agree, hence the "if;" I tend to be very conservative about new forces introduced and the like, no matter how exciting. I remember the search for the "fifth and sixth" forces decades ago, as well as the more recent failure of the EM drive.

Oh, I was not thinking of extracting energy via the Penrose process or anything similar. Rather, I was considering the need for baryons to create structure in a universe without many of them to go around. That'll be the next level of scarcity once you have switched to a civilization that only increments state changes as energy becomes available ... what do you build stuff out of? Baryon farming will be it.

Personally, I rather doubt the math will work out. I think baryons will fall apart one way or another on a scale that will probably outstrip most black hole evaporation unless a civilization was very crafty about trying to find the black holes that were below the usual three solar masses and instead opt for the little ones.

It's a fun thought experiment.

> baryons will fall apart on a [lonnnng] scale

I doubt it. A more practical problem might be keeping baryons from falling into black holes or escaping to infinity (in which case, nobody will care if they decay or otherwise disintegrate eventually).

There's evidence (from the solar system and from gravitationally bound multi-body systems outside it) that there is to all practical purposes no metric expansion of space within clusters of galaxies, which are the largest known gravitationally-bound system, nor any subsystem within such clusters. A hypothesis that involves the metric expansion (or a "fifth force" form thereof) disintegrating atomic nuclei is at this point very far-fetched.

Instead, let's consider a "swiss cheese" cosmology where in the large galaxy clusters are homogeneously and isotropically embedded within a "cheese" of expanding Robertson-Walker spacetime. Each cluster can be represented by an eventual vacuole -- a hole in the cheese -- initially filled with gas and dust. They are "eventual" vacuoles because gravitational collapse will tend to condense the gas and dust into the centre.

Mathematically, in the large these vacuoles can be represented as Lemaître-Tolman-Bondi-style collapsing dusts, where we can recurse, with subsystems like galaxies also behaving over long timescales as LTB collapsing dusts, likewise galactic nebulae and star systems. Everything inside a galaxy cluster tends to condense; and all galaxy clusters end up with more space between them over time.

In solving "swiss cheese" cosmologies, or recursive LTB-style systems, we can employ an Israel-Darmois thin-shell junction as a boundry between the subsystems on which we can stitch together fractions of geodesics of matter and light travelling across the junction. For example, simplifying by among other things employing maximal spherical symmetries, an isotropically radiating star sends photons across the nearest junction into its isotropically radiating nearly spherical galaxy; the galaxy shines into its cluster across a junction; the cluster shines into the "cheese". We can study the flow of radiation out of the topmost LTB vacuole into the "cheese". We can also study the flow of thin wispy stuff -- the CMB, but also radiation, neutrinos, and cosmic rays from distant galaxy clusters -- from the cheese into the vacuole.

For physically plausible arrangements of this sort of model, galaxy clusters barely change their mass-energy at late times (i.e., from ca. ten billion years ago to the practically infinite future), even though some gas (in the most general sense of baryons, photons, neutrinos, and so on) escapes them. Adding in colliding galaxy clusters (like Bullet) in small numbers doesn't really change this picture.

The baryons and other gas that remain within the "topmost" thin-shell pretty inevitably condenses into ever larger sets of black holes, which merge into ever larger black holes at the centres of each vacuole. Hierarchical supermassive black hole mergers might keep these giant black holes always colder than what's left of the ever thinning, ever colder cosmic background, or at least they will gobble up practically all the baryons in today's "topmost" holes-in-the-cheese, save for the small amount that drifts out into the expanding cheese (too slowly to ever fall into a second vacuole, but fast enough to escape their parent vacuole forever).

In the far far future -- ignoring the Boltzmann Brain problem -- baryons will probably only exist in the "cheese" at great distances from the ultramassive black holes that ate all the others. The Boltzmann Brain problem isn't so bad: very occasionally baryons will spontaneously appear very briefly before disappearing again. However, such fluctuations can generate implications for black hole evaporation.

>50,000 years - The length of the day used for astronomical timekeeping reaches about 86,401 SI seconds due to lunar tides decelerating the Earth's rotation. Under the present-day timekeeping system, either a leap second would need to be added to the clock every single day, or else by then, in order to compensate, the length of the day would have had to have been officially lengthened by one SI second.

I guess we have another annoying clock problem to work on once we get done fixing the Y2038 and Y10k bugs.

Some of Stephen Baxter's [1] books in the xeelee sequence explore a sci-fi version of this [2]; it's a fascinating ride, if you are interested in thinking of how sci-fi has dealt with this..

[1] https://en.m.wikipedia.org/wiki/Stephen_Baxter_(author)

[2] https://en.m.wikipedia.org/wiki/Ring_(Baxter_novel)

Made me think of the Dancers at the End of Time books, although they're more philosophical than sci-fi.


Btw, what I don't get about black holes: why is everyone so fixed on the event horizon and calls everything below 'a singularity'?

From our point of view, of course, we don't have much use for it. But inside it might be rather interesting. For one thing, everything under the event horizon is unlikely to be homogenous. Captured matter is likely to form a much less object in the center of the hole, with a much smaller radius. Between EH and this 'core' many things can happen. For example, if matter forms N accretion disk spinning around the hole and just above the EH, why should it stop doing the same thing after it goes below? Only because we no longer can see it doesn't mean it stops existing and loses all energy and angular momentum. Or it does?

> why is everyone so fixed on the event horizon and calls everything below 'a singularity'?

They don't. The event horizon is at r = 2M. The singularity is at r = 0. There is an interior region in between, so the singularity is not "everything below" the horizon, and I'm not aware of any reputable source that says it is.

> why should it stop doing the same thing after it goes below?

It's not that infalling matter will suddenly change its behavior as it crosses the horizon: it won't.

It's that infalling matter has very little time once it crosses the horizon, before it hits the singularity. For example, in a 1 solar mass black hole, it's only 10 microseconds from the horizon to the singularity. Since the time is linear in the mass of the hole, that means that for, say, the 3 million solar mass hole at the center of the Milky Way, it's only 30 million microseconds, or 30 seconds, from the horizon to the singularity. And even for the most massive hole we've observed, 66 billion solar masses, it's only 660 billion microseconds, or 660,000 seconds, or less than 8 days, from the horizon to the singularity. On a cosmic scale these times are very, very short.

> it doesn't mean it stops existing and loses all energy and angular momentum. Or it does?

Any energy and angular momentum of matter falling into the hole gets added to the hole's mass and angular momentum.

> It's that infalling matter has very little time once it crosses the horizon, before it hits the singularity. For example, in a 1 solar mass black hole, it's only 10 microseconds from the horizon to the singularity.

Why should it be hitting the singularity at all? Why can't particles have a stable orbit just under the event horizon? Is it because the orbit speed would exceed the speed of light?

> The singularity is at r = 0.

Also, why singularity at all? Neutron stars compress to a certain density and then stop compacting any further. Of course, gravity in black holes is stronger, but why people think that all matter would compact into a singularity? Can't it be a very dense object where compacting force is compensated by matter density limit? (i don't know the exact term in english, sorry)

> Why should it be hitting the singularity at all?

Because the singularity is in the future of every event inside the horizon. It's a moment of time, not a place in space. It can't be avoided because tomorrow can't be avoided.

> Why can't particles have a stable orbit just under the event horizon? Is it because the orbit speed would exceed the speed of light?

That's one way of looking at it, yes.

> why singularity at all?

Because that's what the math of GR predicts.

> Neutron stars compress to a certain density and then stop compacting any further.

Neutron stars have a maximum mass limit. So do white dwarfs and every other kind of stable compact object. Anything over that maximum mass limit has to collapse into a black hole.

> Can't it be a very dense object where compacting force is compensated by matter density limit?

Not for objects above the maximum mass limit. See above.

> Neutron stars have a maximum mass limit. So do white dwarfs and every other kind of stable compact object. Anything over that maximum mass limit has to collapse into a black hole.

See, this is the crux. From what I read in GR theory, once the neutron star gets over mass limit, the gravity becomes that big that light can't escape it any longer. OK. Light can't escape. Buy why would a matter suddenly work radically differently under the event horizon?

Imagine an asteroid, which has an escape velocity of 1m/s, so it's inhabitants can launch pinballs to outer space with a simple catapult. This asteroid eventually collides with another one, with an escape velocity of 2m/s, so pinballs wouldn't leave the body's gravity field. Nothing really changes on the asteroid, all physics processes work in the same regular way.

Why should it be that different with neutron star vs black hole? NS with ~3 solar masses has radius ~10km, and is a giant lump of neutrons packed together. To me it looks like BH should be the very similar lump of neutrons, just so heavy that light can no longer escape. So what? It should still be a spherical lump of neutrons underneath, just denser.

> From what I read in GR theory, once the neutron star gets over mass limit, the gravity becomes that big that light can't escape it any longer.

No, that's not what happens. What happens is that if a neutron star just under the mass limit gains some mass, it collapses into a black hole. It does not just change a little bit. It changes a lot.

There is no such thing as a static object that is "just short" of being a black hole. A theorem called Buchdahl's Theorem says that no static object can be smaller than 9/8 of the Schwarzschild radius for its mass, i.e., 9/8 of the size of a black hole of the same mass. That means there is a finite gap in size between any static object and a black hole. So any transition from some static object, whether it's a neutron star, white dwarf, or anything else, to a black hole can't be a small continuous transition.

> why would a matter suddenly work radically differently under the event horizon?

It's not "matter" that "works differently", it's the geometry of spacetime itself. The geometry of spacetime inside the event horizon is simply different from what you are used to, and has different properties than those your intuition is familiar with. One of those properties is having a singularity a finite time in the future.

> To me it looks like BH should be the very similar lump of neutrons, just so heavy that light can no longer escape. So what? It should still be a spherical lump of neutrons underneath, just denser.

No, that's not what a black hole is at all. A black hole is vacuum inside. It is not an ordinary object made of matter. It is made of very unusual and counterintuitive spacetime geometry. Nothing else.

As for the matter that originally collapsed to form the black hole, it continued to collapse until it reached zero size and formed the singularity. It isn't there any more. While it was collapsing, its physics was the same as for any other body of collapsing matter; nothing about that changed when it fell below the event horizon. But the black hole is not made of the matter that collapsed.

The "black hole" concept you are describing would make sense in Newtonian physics (and indeed John Michell in the 1700s proposed a similar model of a Newtonian gravitating body with escape velocity greater than the speed of light that worked like this), but it is not possible in GR. GR is not the same as Newtonian physics.

Are there similar predictions but on a short time scale. Like from now until 10,000 AD?

Culture, technology, and geology (and hey, everything else, biology, astronomy..)

I find it hard to try and see what the future may hold, and it seems that is the case since we're at an event horizon of human culture change. Talks of singularity already having come upon us is relevant in terms of predictability to a certain extent, but I kind of feel comfortable to say that humanity will indeed stabilize in at most 5k years, since we're already hitting marginal returns in technology investments. There might be two more singularities that can unlock more unpredictability: AI and biology.

I was always looking for some “realistic” SciFi for the next let’s say 500-1000 yrs. I couldn’t find anything that didn’t include some stuff that was clearly coming out of the Fantasy domain

Well, 120 years ago moon landing was from fantasy domain too :)

Fair enough :)

AI overtaking humans and maybe some kind of merging with that is bound to be a big change. Bit hard to see beyond that.

There's this, but it only goes to 2280: https://en.wikipedia.org/wiki/Timeline_of_the_near_future

Looking at the future of humanity section:

> 10,000 - If globalization trends lead to panmixia, human genetic variation will no longer be regionalized, as the effective population size will equal the actual population size

> 10,000 - Humanity has a 95% probability of being extinct by this date, according to Brandon Carter's formulation of the controversial Doomsday argument, which argues that half of the humans who will ever have lived have probably already been born.

So in 10,000 years we're either all going to look the same or we'll all be dead? Yikes.

Those aren't (and aren't implied by the article to be) the only two options. Globalization could recede (or at least not progress); the Doomsday argument could be totally wrong (it's logically sound, but based on some strange statistical assumptions); or we could colonize other planets to a point that would both inoculate us against most extinction scenarios and create isolated genepools, just to name a few others.

"no longer be regionalized" implies greater but not absolute homogeneity to me. There will likely still be variation, but it won't be associated to different countries or continents as it is now.

So, a slim chance racism will cease to exist.

There was an artistic video about the far-future timeline, part of it was post-humans first jumping form star to star, then making new stars from hydrogen, then splitting stars into small stars to conserve hydrogen, then sitting out the rest of their existence around one last decaying star.

Anyone remembers that video? Wish I could find it now.

Heat death is also the central plot of Asimov's short story, "the last question": https://en.m.wikipedia.org/wiki/The_Last_Question

I came across that just yesterday funnily enough through Scott Adams going on about a podcast featuring it. (American Red Pilled, Let there be light)

I haven’t watched them again now to check if it’s one of them you’re searching for, but these two videos have been posted everywhere last year:

[1] https://youtu.be/uD4izuDMUQA

[2] https://youtu.be/SUelbSa-OkA

+1 for that first video

Some events have a 5k years period between them but the first one "far" in the future is 10k years from now. I wonder though, are there any imminent or very likely event to happen between today and the next 5k years? I mean, that would fall in the categories listed there...

For Europe that would certainly be post-glacial rebound. Gulf of Bothnia cut off from the Baltic Sea, and England slowly sinking (many people would have strong opinions about it, I guess). Netherlands and Venice are a league on their own with sea flooding problems.

Then pale skin and blonde/red hairs evolved when humans started to reclaim land after withdrawal of glacier in the same region of Europe, so 5k-10k years is sufficient for a new appearance feature in humans to evolve.

Makes cleaning the garage seem a bit futile.

certainly, why bother? :-)

In the same vein there was a joke that goes something like this:

A professor is giving a lecture and he says:

-"In 4 billion years Andromeda will collide with our galaxy".

Somebody in the audience stand up and says:

-"Excuse me! did you say 4 billion or 4 million?"

-"Four billion"

-"Dude... you worried me there for a moment.."

The most mind-bending parts are those that occur beyond Heat Death.

Roger Penrose has really mind-bending observation and theory about the time past heat death in the 'Cycles of Time'.

After 10e100 years when there is only massless particles like photon's left and black holes have evaporated, time essentially stops existing. Photons, gluons and gravitons just go without any new events to infinity.

What you're describing is still technically Heat Death. I'm talking about after that. Technically, if anything can still evaporate, you're not yet at true Heat Death.

But infinity is a larger number than even the exceedingly unlikely probability of Entropy spontaneously reducing, just like there's a finite possibility of all the air deciding to move to the other side of the room without any external actions. Quantum fluctuations can produce stuff from nothing, they just never do with any appreciable probability.

But Infinity swallows up even Heat Death.

Also listened to this and was mind-blown. But my take away was that at this point photons can then "make it to infinity" which sort of meant they will get through to (or cause?) the next big bang. Maybe all the photons combine and cause the big bang? One thing I didn't understand was that he said this meant that signals could make it through to the next iteration of the universe. However my understanding was that all photons are scattered by the surface of last scattering (CMBR), so how could this be possible?

Spontaneous entropy decrease that leads to Big Bangs at least every 10^10^10^56 years.

Well after heat death and "final" energy state of the Universe.

10^10^10^56 years sounds like a long time, but it's way smaller than infinity... Imagine Graham's number, which is still finite and thus much smaller than infinity... https://en.wikipedia.org/wiki/Graham%27s_number

Can't those photons scatter off each other?


Similarly for the other bosons, they can probably scatter off each other, mediated by virtual particle-antiparticle pairs.

Energy of photons is too low after a while. No gamma photons.

Ah, but that merely reduces their probability. Over an infinite timeline, anything with a small but still finite probability of happening will eventually happen (and, I think you could say, happen an infinite number of times...).

A prediction for 1.1 billion years in the future:

> The Sun's luminosity has risen by 10%, causing Earth's surface temperatures to reach an average of c. 320 K (47 °C; 116 °F). The atmosphere will become a "moist greenhouse", resulting in a runaway evaporation of the oceans.[65][70] This would cause plate tectonics to stop completely, if not already stopped before this time.[71]

Would somebody be able to ELI5 the connection the Earth's average temperature and plate tectonics?

Not a geologist, but I rember reading something about this a while back, so this might be BS. I believe it's because the water being pulled down at the subduction zones (where one plate gets forced down under another) help lubricate the whole process. I think that without that water I think the mantel becomes too stiff.

>The red supergiant star Antares will likely have exploded in a supernova. The explosion should be easily visible on Earth in daylight

How would that look like? Can't imagine it.

The wiki links seem to say that they expect the supernova to register at -12.5 apparent magnitude. The sun has an apparent magnitude of -27, and the full moon has an apparent magnitude of -12.

So the supernova will first appear as a single dot approximately as bright as a full moon hanging in the sky. I don't know how large the explosion will appear, but the article on the Crab Nebula (https://en.wikipedia.org/wiki/SN_1054) which was probably observed by Chinese (and other) astronomers in has some descriptions, as well as a simulated image of the skyscape the astonomers may have seen. SN 1054 was estimated to have an apparent magnitude of -6, so like 250 times dimmer than they think Antares will be.

Venus is visible in daylight but not that easy to find. So maybe the Antares supernova would be like a brighter Venus.

thank you for this wonderful rabbit hole into Boltzmann Brains! https://en.m.wikipedia.org/wiki/Boltzmann_brain

Still too early to invest in real estate on Lōihi, dammit. Post-glacial rebounds in Scandinavia and Canada are much more promising.

Somewhat related: "The End of the World", which is an 8-episode podcast which presents some of the ways how the world could come to an end.


I love this kind of long term timeline.

One science-fiction author writing about far futures is Stephen Baxter.

So, GWT 3 won't happen ever. OK.

There is a lot of awful naming throughout the scientific community, but "Milky Way" has long been my personal least favorite.

'...the Andromeda Galaxy will have collided with the Milky Way, which will thereafter merge to form a galaxy dubbed "Milkomeda"'

Now it's my second least favorite.

"Galaxy" and "lactation" share etymology. Funny, isn't it?

…and it's not like the scientific community even existed when Milky Way was named like that in English.

Maybe you'll prefer the original (dead-language) Latin version: Via Lactea. Sounds cooler to me, maybe because it's a Dead language name.

Incidentally that is exactly what we call it in Spanish.

Fun tangential fact: "Star Wars" in Spanish is known as "Galaxy Wars" (La Guerra de Las Galaxias.)

Sounds like how the Ancients in StarGate series would call it.

Well "Andro-milk" sounds like a muscle supplement..

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact