There is no real information in this article. Roger Penrose has, as he himself puts it, a crazy theory that a universe existed before the big bang, and that the heat death of the universe starts a new big bang. That's the kind of chat you have over a few pints on the weekend, because there is nothing worth "media"ing about.
It's really not a crazy idea at all, though. It's certainly less crazy than how much of established scientific canon would've appeared to the world when it was originally proposed. I would argue most of quantum field theory is much "crazier" than Penrose's CCC idea.
That said, as far as I know it falls into the body of theories that struggle to make falsifiable predictions, and of the limited such predictions it has made nobody has found data that validates them in a statistically significant way yet.
Ok so a beer talk question to the physicists: By any measure of order, there are more disordered states than ordered states, and therefore any random change is likely to be a change to a more disordered state, leading to the inevitable heat death of the universe. But if this decent into chaos is only about probability, then given infinite time even the infinitesimal chance of spontaneous order will have it's moment.
With infinite time will order spontaneously emerge from heat death?
There's a theorem "Poincaré recurrence theorem" which says if a system is finite, given infinite time, it will return to a state arbitrarily close to its initial state.
While the theorem itself is well proven, I can't find a physicist who can say one way or another whether this applies to our universe.
My apologies, but I believe that this theorem applies to a subset of possible systems with certain properties which are called "conservative systems," not any arbitrary system.
The objection hasn't been made in your SE question, so I assume I am missing something, but why does 'if a system is finite' apply to the universe? The 'given infinite time' would need to be a 'faster' infinite than universal expansion?
The food on your plate is finite, but if you're served more faster (no slower) than you eat it, then you won't empty the plate even given infinite time.
The observable universe would have to be a conservative system for Poincaré recurrence to apply to it. I don't think that's possible; isn't it leaking matter that looks like it won't come back?
I don't understand all the properties a system must have so the Poincaré recurrence theorem applies, but as long as we don't know whether the (entire) universe is finite, that's sufficient to show that Poincaré recurrence may be impossible. In that situation, we can either find information that makes it impossible for sure, or otherwise we know that we don't know.
‘Nothing else can affect us‘ doesn't contradict that, because ‘us‘ would cease to exist at the Poincaré recurrence time (if not earlier).
N.B. I'm just pointing out some basic things, while having no clue how much merit the idea has in the first place, even if the universe has finite state space and infinite time. (I mean just the idea of trying to apply the Poincaré recurrence theorem to the whole universe, not Penrose's work.) AFAICT the proof only says that almost every state recurs infinitely often. So if you picked some state at random as your starting state, it's essentially guaranteed that it will recur, but when it comes to applying this to the universe, isn't it presumptuous to regard the big bang as such a state?
Assume that the volume of the visible universe grows, and then consider a ball that just circles on larger and larger circles. Clearly, the ball does not need to get back arbitrarily close to where it started.
I like your reasoning. Feynman pointed out why this doesn’t work: you have to “borrow odd”, so to speak, in order to get any effect. Which means that your slight perturbation, although miraculous, ends up having little more than an infinitesimal effect over an even smaller amount of time.
Feynman put it way better than me though. It was in the Messenger Lectures series if you’re curious. 6 wonderful and accessible videos; his audience was primarily laypeople, not scientists. Quite enjoyable.
Feynman's argument was about why you can't have systems that decrease entropy continuously. It doesn't disprove that there can (and will) be downward fluctuations in entropy, which is what I believe the OP was asking about. As someone else mentioned this is the idea behind a Boltzmann Brain (which is a pretty fascinating concept).
Heat death leads to absolute uniformity throughout the universe and when that happens, when no two points of the universe differ in any way, the universe becomes a single point and then a big bang occurs, according to Penrose.
Basically when all particles are moving at speed of light, time becomes meaningless and you can consider space to be infinitely small. I.e. identical conditions to Big Bang
> With infinite time will order spontaneously emerge from heat death?
The theory is more that with "infinite" expansion, the universe becomes so spread out as to in spot become emptier than the vacuum energy, and a new universe spontaneously erupts in that low energy locale. In a very small nutshell.
This relates to one of my favorite wikipedia pages: The Timeline of the Far Future.
The relevant part is at the end. Essentially, given enough time, quantum effects will result in an entire new universe spontaneously popping into existence. That time is ~10^(10^(10^56)).[0]
But, the number of ways that all particles in the universe can be arranged is only ~10^(10^115). That number is much smaller than the time to just go 'pop, new universe'. So, the much larger number also becomes about the time it takes to just have a new universe identical to our current one just go 'pop, new universe'.
The other entries in that article are just as joyously mind-bending. I really really love that page!
[0] Side note: The time for a 'Boltzmann Brain' (a consciousness that just floats in the infinite void thinking away, somehow) to spontaneously appear is only ~10^(10^50).
Also, I forgot to mention that all these timelines are in years.
But then I thought about it and about any human unit of time really doesn't change the numbers much at all. Heck, even measured as units of 'age-of-the-current-universe', the extra 0s just fade into the rounding errors very quickly.
To be clear here, that is stating that however you measure time pretty much has no meaning at these scales.
> But then I thought about it and about any human unit of time really doesn't change the numbers much at all.
As the Wikipedia page[0] puts it:
> Although listed in years for convenience, the numbers beyond this point are so vast that their digits would remain unchanged regardless of which conventional units they were listed in, be they nanoseconds or star lifespans.
>With infinite time will order spontaneously emerge from heat death?
The answer may be yes or no in any particular axiomatization (model) of the physical laws, but depends strongly on the choice of model. Unlike a normal situation, when we talk about very-low-probability effects we are subject to any influence of "quantum gravity" and other "new/unknown physics" that may have a finger, however light, on the scale.
In the Standard Model I think the answer is yes, but we are already aware of some deficiencies (neutrino transitions).
> then given infinite time even the infinitesimal chance of spontaneous order will have it's moment.
Does this hold true for a 1/infinity chance event?
Or (not sure if this is analogous) if you choose infinitely many real numbers ~ unif(0, 1), is it guaranteed you will hit every number in that interval at least once? I'm not even sure the question is well-defined to be honest (at least not without making assumptions about infinities that we have no way to show hold true for this universe), but if it is, is the answer yes? It's not obvious to me.
The first is not well defined, the second is and as long as we are talking countable infinity, it is not. (In the uncountable case you are running into problems with definitions again.) As a matter of fact, you will not hit almost all numbers. However, you will almost surely have picked a point in any fixed interval, and that is meant with order reapers over long enough timescales.
For illustration, you are almost guaranteed to not win the lottery, but when you play again and again, then after something like 14 million times playing (for the German Lotto) you will win, and again after something like 28 million times playing, and so on, so you expect to often over long enough timescales, and you can start to impose additional constrains, for example winning with consecutive numbers, or the first few primes. And after a long enough timescale you start to win again with these additional constrains.
For example a complete brain capable of imagining it’s in a universe could spontaneously occur... (Boltzmann brain) but the catch is that there needs to be enough usable energy for it to function. So even if order suddenly occurs, heat death means an eventual limit to complexity.
Ultimately something needs to happen to cause a sudden reverse into very low entropy, ie another Big Bang or something of the like.
We’re talking like 10^50 years here before heat death ends thought so... the universe has some time still.
This is the Boltzmann Brain paradox -- given this probability system, it's much (not going to say infinitely... but practically so) more likely that your perception of this moment is a fluctuation in chaos than that the entire universe as you perceive it currently exists. The parallels to the simulation argument/doomsday hypothesis are, I hope, apparent.
> It's really not a crazy idea at all, though. It's certainly less crazy than…
When someone comments on the craziness of theories about before the big bang (and therefore the cause to which it was an effect), it is always worth remembering that the big bang itself was considered crazy by many initially.
The name even came from a dismissive description (with massive vocal air-quotes around "big bang") that just stuck as it is actually a good description (at least by dint of being catchy).
Crazy does not necessarily mean something is incorrect.
It really is. Every physicist has a dozen ideas like that they realize are stupid, have no evidence for and can't really be proven or disproven with current data.
We call them crazy to keep our selves from going off the deep end and talking about ufos, the foundations of mathematics or the genetic differences between races.
I'm kind of shocked there's nothing on the front page about Penrose winning the Nobel prize for physics. The guy is really a polymath, even accounting for his outlandish and sometimes discredited theories.
Even so, his black hole theory also had a long time coming to acceptance. What he says might be hard to prove, but it doesn’t sound totally absurd, and probably also isn’t an uneducated guess by someone who knows the math.
> a crazy theory that a universe existed before the big bang, and that the heat death of the universe starts a new big bang.
I realize this isn't what Penrose is saying, but is it really that crazy that random fluctuations will create the conditions for a new big bang in a universe at thermal equilibrium?
It's not useful to speculate about things that are unfalsifiable. That's why Penrose wants these things to be observable traces from before the big bang.
> It's not useful to speculate about things that are unfalsifiable.
I disagree. While such speculation obviously won't produce immediately useful data, where would we be today if noone had ever speculated about something which at the time could not be falsified? Case in point: the initial speculation on the existence of germs, which at the time was unfalsifiable.
From the arcticle: "By the early nineteenth century, smallpox vaccination was commonplace in Europe, though doctors were unaware of how it worked or how to extend the principle to other diseases."
So doctors were saving lives even though they had no idea exactly how or why it worked. They could neither prove nor disprove why it seemed to work, it simply did. The fact that it was unfalsifiable had nothing to do with the truth of the matter - it still saved lives.
I think there's a difference between untestable in practice, right now, and unfalsifiable even in theory. The latter case can never hold any practical value.
I think the point dumpsterdiver is making is that determining what is falsifiable or not is context/time dependent. As our understanding of reality changes over time so does our definition of what can be falsifiable.
> "Show me," you say. I lead you to my garage. You look inside and see a ladder, empty paint cans, an old tricycle--but no dragon.
> "Where's the dragon?" you ask.
> "Oh, she's right here," I reply, waving vaguely. "I neglected to mention that she's an invisible dragon."
> You propose spreading flour on the floor of the garage to capture the dragon's footprints.
> "Good idea," I say, "but this dragon floats in the air."
> Then you'll use an infrared sensor to detect the invisible fire.
> "Good idea, but the invisible fire is also heatless."
> You'll spray-paint the dragon and make her visible.
> "Good idea, but she's an incorporeal dragon and the paint won't stick."
> And so on. I counter every physical test you propose with a special explanation of why it won't work.
> Now, what's the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all?
> If there's no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists?
> Your inability to invalidate my hypothesis is not at all the same thing as proving it true.
> Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder.
Well, if the dragon exists it must have the characteristics of a dragon. Let's say it must be an animal with four legs and a tail. Currently it's unknown whether all animals are q-conscious[1]. Let's say it is discovered that all animals are q-conscious. Therefore the invisible dragon is q-conscious.
Currently we don't really understand qualia, but one mainstream theory is that qualia are a different kind of thing to anything else we know about (i.e. are non-physical).
Let's say this theory is true, and, further, that a method for detecting this different kind of thing is detected. That the dragon is invisible, floats, is heatless, is incorporeal, doesn't matter.
The theory that there is a dragon in the garage is falsifiable by the observation that a scan for qualia results negative.
You could say "ah, but this dragon is the dragon of any-test-you-can-come-up-with-doesn't-work, therefore you can't come up with any test which would work". But that would be begging the question.
If you've not yet experienced H2G2 I suggest tracking down the original radio version before the books, TV, or more modern film - it is widely available to buy in various formats. It is justly recognized as a classic.
It seems not only has he made multiple predictions based on this theory, but he also is actively publishing research showing it may be true. Where do you get unfalsifiable from? There’s literally falsifiable claims being made.
There are a lot more books sold on speculative fiction than real astronomical insights. Clearly, such speculation serves a purpose and must therefore be considered useful.
A couple of theories regarding the ultimate fate of our universe are the Big Crunch (everything comes together) or the Big Freeze (everything drifts apart, forever). I agree that it's not hard to imagine that if a Big Crunch happened it could potentially create another Big Bang. That said, there's still no way to necessarily prove that.
I feel like this is a good time and place to bring up an idea that I sometimes like to entertain. It goes like this:
There is some number of dimensions that exist in total, which is a number higher than just the four dimensions that we are readily able to observe. Our universe exists within this higher dimension, alongside other universes.
Also, what we perceive as linear time within our universe might not be just a single dimension either. But even if it's not we can still treat it as though it was.
The laws that apply within each of these four dimensional universes as we might see them might or might not all be the same laws. I.e. all other universes might have the same laws as does ours, or some might be different, or all might be different. We can't know.
But the idea that I like to entertain is that these universes could serve some function within the higher dimensions.
For example, a set of many many parallel universes might each function analogously within the higher dimensions as to how cells function in our universe, and that analogously these parallel universes form a greater whole together as some sort of being that is made up of all of these.
Or another possibility might be that a universe could be able to develop within itself life that is able to sense the higher dimensions, and to break free of the universe within which it was created and to then continue existing in the higher dimensions beyond the end of the universe that created it. I imagine this not as human with more senses, but something very different. For example, the way it might come into existence in our universe could be through machinery that we create, with mechanical sensors that are able to pick up the other dimension(s), and with increased computational power the machines we create could in turn process all of the information available to it in order to construct something that somehow (yes, very vague sorry) is not limited by the reality of our universe itself.
But yeah, there is no scientific basis for said ideas. It's just something that I like to imagine.
It’s quite fun to speculate. If you’re into this sort of thing, you’d like lemmino on YouTube. Pick any one of his deep dives and you’ll end up listening to something pretty close to what you did here: speculation, in a tight straight jacket.
Part of the problem with dark energy is that so much of it is unfalsifiable in ways similar to these theories. Of course, the key difference is that we can measure the effect dark matter has on the universe, whereas thus far no more than 4 dimensions have ever been observed.
Sure makes drinking fun though. Take a sip and say a hypothesis. Like apples to apples but for physicists.
If I were having a pint with Penrose, I'd take it a step crazier: what if the earlier universe is actually this one? And our universe ends up in a Big Bang, which begets a new universe, which is the one we are now in.
According to CCC and to my understanding, it is sort of the case. The universe has undergone a "scale change" which marks the beginning of a new Epoch.
It's explained in this PBS Space Time episode much better:
If that's the case, then wouldn't we have some kind of special background radiation? Penrose stated that some things must be visible through background radiation right? (something with black holes of the preveious aeon)
If that's the case, then we might be able to observe that state and try to workout, whether we get to that same state.
There's BBC Horizon episode called "What happened before the Big Bang?" where Penrose stated that he used t to kinda roll his eyes when people asked what happened before because the question didn't make sense.
The whole episode is a wild ride including people from the Perimeter Institute proving soon to me how bizarre theoretical physics is at its frontier. Highly recommended watch.
Yeah Penrose idea is logical but then very vague on the proof side.
It obvious we re misrepresenting reality by saying it started with a big bang, and there must be a simple way out of infinite looping or creation from the void in higher dimensions.
But I stopped dreaming with Penrose because it always just stop at "but this is all just me saying it" kind of.
What, if some day or night a demon were to steal after you into your loneliest loneliness and say to you: 'This life as you now live it and have lived it, you will have to live once more and innumerable times more; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unutterably small or great in your life will have to return to you, all in the same succession and sequence' ... Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: 'You are a god and never have I heard anything more divine.'
Yeah I really like going back through 20th century science fiction and seeing echoes of contemporary topics or history in the varying and wild guesses we got back in the day.
IIRC Heinlein's 1940 "The Roads Must Roll" for example invents the Segway (a self-balancing single-wheeled vehicle used by engineers maintaining ultra-high-speed moving walkways that everyone commutes on).
I just read Asimov's "Breeds There a Man...?" (1951) and couldn't shake the feeling that it was echoing Thomas Kuhn's 1962 theory of scientific development.
Really? I honestly think it ranks pretty low on the scale Asimov's works. The 'big reveal' isn't very interesting or unexpected, and there aren't even any really interesting ideas explored in the work.
Then again, I'm apparently in the minority in my belief that the Foundation series isn't that good either and The God's Themselves is clearly his best work, so YMMV.
Congrats to Sir Roger Penrose, I think it's a fitting tribute that he named the 'warm' points after Hawking.
Both of them are my favorite popular-science authors. My apetite was whetted with Hawking's "A Brief History of Time", which led me to Sir Roger's "The Emperor's New Mind". Although relatively denser, with much focus I was able to understand the topics he covered (which were fascinating, and I still think about them) but I could never explain it back to you if needed!
Emperor's New Mind absolutely infuriated me when it came out. I waded through the whole thing only to find the it's thesis could be apparently boiled down to 'consciousness is spooky, you know what else is spooky? quantum stuff - microtubules are small, I bet quantum effects are involved'.
Now, I've no-doubt I'm doing the great man a disservice, but it felt like a very thin conclusion for such a fat book.
That's practically word-for-word the description of the book I've always given. "We don't understand consciousness, and we don't understand quantum mechanics, ergo...."
It's a pity, because that was those books were my first and only experience of Penrose for many years, and it was only much later that I learned of his much more interesting work in geometry and mathematics, and their use in physics, the study of crystals, etc.
Those are indeed fascinating, but what could be more interesting than the relation between consciousness and the Universe? Maybe you're preference is for the more solid ground of confirmed science, which is understandable, maybe you didn't have the patience to follow his thinking, which is ok too, but why go the extra step and caricature his arguments like this?
My undergraduate degree was in Cognitive Science. I took a large amount of neuroscience, psych, and philosophy. Discussing consciousness was the part I loved the most, and I had plenty of patience for plenty of writers.
My dismissal of his work on consciousness was based on those grounds. I think my "caricature" was fairly accurate, but if you think different that's fine, if you can elaborate.
The part I forgot above was that I also dismissed it on the basis of math, which is surprising given that Penrose is a greater mathematician than I'll ever be, but his whole reason to evoke "quantum" was that a Newtonian-based brain could not know that a "Gödel sentence" was true, so our brains must be non-Newtonian. It was absurd on the face of it (our brain's belief about statements don't constitute a formal logic), and was also well-criticized by other mathematicians, whose names I'd have to dredge out of my 20-year old essays.
Yes, I'm aware of the criticism and it might be that only a few of his speculations find ground in reality, or even none at all. Still, these dismissals are unfair and rouhghly equivalent to saying that for example, Darwin's "Origin of the Species" boils down to "life-forms are groovy".
As someone who took a number of mathetical logic classes between undergrad/graduate I always found this Gödel-sentence argument on the face-laughable, since the logical inconsistency was so easy to repair. My favorite critique of this was Hans Moravec's dialogue between Penrose and a robot AI, having resurrected his brain long past humanity's extinction: http://www.calculemus.org/MathUniversalis/NS/10/10moravec.ht...
Once you move into the realm of untestable vague hand waving statements, it’s not really even science anymore. Philosophical discussions that dress up like science are infuriating for anyone who went in looking for science.
I understand that for someone who appreciates science, but not philosophy, the book turning out as straddling those two fields might be a letdown. But that's not the authors fault since those books are not presented as academic research, but only informed by it.
Infuriating for me are philosophical discussions which don't draw substantially on science.
I felt let down by Penrose, because the book was dressed up as sonething it was not. By comparison Dennett and Pinker and Hofstadter were much more satisfying.
Yeah, of course you're doing him a disservice. Maybe try reading it a second time (and third too, why not), with more patience. It definitely doesn't boil down to what you just said.
See my reply on a sibling comment. Also, it's one of very few popular books that goes deep on the subject of Goedel's Theorem and the limit discoveries in logic and computability. A subject that in my view deserves to be more in our collective consciousness than even Quantum Physics since it's implications are likely to be even more profound.
If I remember right, that section didn’t differ substantially from Lucas’s argument, which I thought had already been effectively rebutted (eg in Godel, Escher, Bach). But maybe I’ll take another look and see if that’s fair.
Because free time is finite. If they read it three times and still decided it verbosely failed to make its case, why not read it two or three times more?
Can you cite a point or two where you think Penrose makes a strong case above and beyond "consciousness and quantum theory are both mysterious and are therefore probably connected?"
Of course. He talks about research on quantum effects in microtubules, for example. Of how the concepts of computability and consciousness relate, how quantum physics drags in this concept of consciousness into science hitherto imagined purely objective. There are so many interesting connections, which might well be directions science will investigate in the years to come. That's a big part of what the whole book is about.
The other part is where he describes how quantum physics, logic and consciousness are weird. That's basically just science popularization, coming from a top mind in both math and physics. To me, that's already enough to justify the price of admission: the time and mental effort of going through the book at a pace that assures comprehension, which does take some patience.
Imagine looking at a reactangle that gets thinner and thinner until it's just a straight line. And then imagine that you shift your point of view, to see that actually that line has depth, and from the side the "line" is actually a new rectangle.
It's not as though the new rectangle suddenly appeared: the new rectangle was always there as one face on what you now realise was a cuboid. However, from your original perspective you couldn't see that face.
This example is not exactly the same as what's described by CCC: I don't know if you could describe each universe as having "new dimensions", and instead of shrinking, each universe is stretching out to infinity, but the "change of perspective" part is a useful analogy I think: each universe only looks like it starts at a single point if you observe it from the the right frame of reference. If you could somehow observe our big-bang from the reference frame of the prior universe it would be indistinguishable from an infinitely spread-out empty universe.
According to CCC (AIUI), all of the infinitely many future universes have already started, but each universe will end before even an instant of time has elapsed for the next universe: that is, "time" as measured in one universe is on an entirely different scale from "time" in another universe.
> According to CCC (AIUI), all of the infinitely many future universes have already started, but each universe will end before even an instant of time has elapsed for the next universe: that is, "time" as measured in one universe is on an entirely different scale from "time" in another universe.
This is superficially similar to the hyperreal numbers, where you can have a set of numbers up to infinity that is strictly less than another similar infinite set.
Is time longer (or shorter) in the next universe? That is, if we could compare seconds or minutes, would the ones in the next universe be longer or shorter?
You could either look at time in the next universe as being infinitely longer, or you could view it as being an entirely different axis from time in the current universe.
I suspect that physically, or even mathematically, it's impossible to draw a distinction between those two descriptions.
I think the argument is that once time stops being meaningful, distance does to, and then “the universe has infinitesimal size and is very hot” is no longer distinguishable from “it is massive cold and empty”.
Massive caveat: I’m not a physicist, and I regularly misunderstand “merely” relativistic physics.
Very interesting idea! Do you have any insights into what then determines the total mass of this new born, infinitesimal, hot universe?
From the infinitely huge and empty universe is born a new universe, but it has some finite total mass. I wonder what describes the amount of mass the empty universe turns into when a new cycle starts.
What you more likely mean is the "absolute" total of both positive and negative energies in the form of light/matter versus gravity respectively. Reminiscent of absolute convergence from mathematics [1]
Amount of gravitational energy is proportional to light/matter, so in theory, we should only need to solve for one thing - the amount of light/matter or the amount of gravity. Since gravity is non-renormalizable (mass -> gravity -> mass -> ........ -> gravity), it's not clear whether gravity or light/matter is more fundamental. They are clearly coupled but one doesn't necessarily cause the other.
Note that the zero-energy universe is highly speculative; in particular there is no good way to define the total energy confined to a volume at large scales and it's hard to say that "energy is conserved" in any way that's nontrivial. (A ready example is the apparent loss of energy in the redshifting of light due to Hubble expansion.)
He doesn't say it's a new universe, e.g. in an interview with Lex Fridman[1] he calls that out and says it explicitly isn't a separate parallel universe. It's more an argument that if you don't have mass because all the mass has decayed, through Einstein's relation of mass and energy and Planck's relation of energy and frequency, and frequency involving distance and time, with no mass, you lose notions of distance and time. Then the infinitly large distant future universe and the infinitely small distant past big bang become indistinguishable with the loss of "large" and "small" to distinguish them. They are both "at infinity", they both "contain" all the energy in the universe, and what we see as a tiny big bang, aliens on the other side saw as a huge expanded universe.
From what I (layperson) can tell, it's like the expand/crunch cyclic universe theory, but without the need to crunch back down again.
What I get from this, and I might be totally misunderstanding, is that we can see it loosely as "zooming out" (or the sake of simplicity) with each iteration, until you're looking at a tiny universe again? So that large vs. small is just a matter of viewpoint.
I'm not sure how to interprete it in that sense, or what the math looks like, I have only Roger Penrose saying "the math checks out" to go on.
Sounds like you're asking "is it really getting bigger endlessly and we take a larger distance as the unit value each cycle" and if so, that feels like the wrong kind of question when talking about distance not existing, but I don't know anything deep about it I've only heard him talk about it in interviews.
I don't really get why you can't reason the other way and say if there are photons and light, then there must be frequency, distance and time, therefore energy, and therefore mass. Heck, maybe that is the same reasoning; there, at the place of infinity, is all the energy and mass which ever was in the universe, all in one place. And what do you get when the whole universe is all in one place? A big bang? Transforming from matter to light (via stars burning and eventually Hawking radiation from the last things remaining: black holes) carries all the energy in the universe off into the distance. Where does it go? Off into infinity. If you take infinity as a place that means it all goes to the same place? Then that process is the "collapse" which brings everything together into the same place ready to be turned into matter again? That's my pop-science understanding of his proposal.
Well, that's not exactly fair; it does make testable predictions, which is nice, and they should be the kind of thing that we would notice anyway (IIUC) as we get bigger and better tools, which makes it cheap to test, which is also nice.
I agree that it's probably not THE ANSWER, though!
mostly hand waving (or quantum fluctuation, or branes, or something like this).
But, since the universe started once, and we are not sure how it got started, there is a chance for something like it to start again.
We will never know, but we do know that universes do start somehow, and the potential ability to detect previous/past universes is very intriguing for sure.
I don't think this is the argument. For someone "inside" the universe it may take an infinite amount of time (as in it will never be observed); however, for some observer in the future it will appear an infinite amount of time ago. Because angles are preserved for all infinity of time there is some information transfer.
Which of these 6 bullets is fringe? For example, is your first point "you need mass to have time. Massles particles don't experience time" a fringe concept?
The fringe idea is that a heat-death universe looks homogeneous and the Big Bang also looks homogeneous and so maybe we could potentially hook up the t=0 of one universe with the t=∞ of another and get rid of the “well but it takes infinite time to get from one universe to another” by handwaving of “yes but no particle in that universe actually experiences infinite time because they all become massless eventually, so it effectively takes finite time.”
Like, the principle that massless particles cease experiencing time itself is fine, albeit kind of hard to think about (it is a negation of an idea; because they don't experience time they cannot “experience” anything, so I could tell you that “they also see the entire universe except for the thing that emitted them as one point/ray straight ahead of them” but I mean they don’t actually “see” anything so I am describing a limiting behavior here).
Whether you can stitch universes together like this is very very fringe but props to him for being a physicist and looking for some sort of observable consequence of a theory that could have otherwise just been a “yeah the math could go either way on this, think of it that way if you want to but there is no pressure.”
I don't think passing through "infinite time" is a fringe concept in modern physics. It is well accepted that passing the event horizon of a black hole involves traveling through infinite coordinate time from the perspective of an outside observer; however if you change your coordinates to that of the object falling into the black hole, you will see that it takes finite time to pass the horizon.
I think that’s almost it, but not quite (big grains of salt here, I’m trying to remember a talk from a decade ago). I went to a talk of his, and iirc it wasn’t stitching t=0 to t=infinity. It’s was stitching t=0 to t=big enough to be homogeneous enough, but there are still itty bitty remnants of patterns left that might be detectable today.
He reuses a lot of his slides, the one that I have a picture of speaks about taking the boundless expansion and performing an “∞-compression” which I am taking to be a conformal rescaling of the state of the universe at infinity, but I must cede to you that this may be a misunderstanding because he also says on this slide that the Big Bang involves an “∞-expansion” and he certainly doesn't believe that the Big Bang was an infinitely long time ago. In any case what I remember beyond this was that he figured that the expansion at the end of a universe could be used to locate the “cosmic inflation” of a universe _before_ its Big Bang, in the heat death of the prior universe, and it was my impression that it was this “evolution to infinity” of the prior universe but I might be totally mistaken.
Curious. Would you think that if Penrose is correct, that each subsequent universe's timeline would be deterministically exact replays of the former universe, or would they have some degrees of freedom to develop differently?
I mean, whether it’s deterministic is really hard. We’re talking about extensions of quantum field theory and there have existed both deterministic and nondeterministic accounts of quantum mechanics, the deterministic ones generally lagging the nondeterministic ones substantially.
But whether it’s _exactly the same_, I think Penrose would say that they are _almost never_ the same. The question would be whether the Big Bang of this universe is perfectly mirrored in its final state and I think Penrose would say “well all the stuff that happened in the middle probably had some sort of effect on how the thing ended up.” So if we are seeing the black holes of some other universe’s death writ large on our cosmic microwave background, then I can’t imagine our black holes will eventually look exactly the same, will they? (Keep in mind, I’ve only met Penrose once and I embarrassed myself thoroughly at the time, so my guesses about what he would say are terribly terribly weak predictions.)
But maybe they will be the same. I talk a lot on HN about the impact of fixed-point theorems on US politics, but they would also apply here. If the universe has an infinite number of sequences one might expect that it starts to converge on a situation where the black-hole-patterns in are the same as the black-hole-patterns out. Now if that happened one might imagine that, if that fixed point supports life, then there is an infinite replay of nearly-identical life experiences across the many many eons of universe, and then if we treat our existence as “choose a conscious person across the eons to be” we would almost surely randomly choose someone in the oft-repeated universe. And so yes, we would be very likely to say that our universe's end would lead to another universe wherein the exact same people living out the exact same lives having the exact same discussion on Hacker News, haha.
I am a Christian and so these sorts of things are a sort of idle speculation, a joke to laugh at rather than something to inform today’s experience, a slacking-off between meetings rather than a contribution of deep value. But it’s certainly fun and funny to think about.
Maybe the previous universe's black hole evaporation ripples cause enough chaos effect for the new universe to be different so even though the whole system is deterministic, it could always be different because of that effect. We live in a PRNG.
Edit: OOh I have an idea. What if the quantum effect is deterministic but appears random we experience are in fact ripple effects from the previous universes? Has anyone ever tried to measure quantum behavior in multiple simultaneous experiments in a kind of geometrical matrix system to see if there are shapes of correlation?
1. Fringe as in the edge, something completely new very few others are pursuing: idea or viewpoint which differs from the accepted scholarship in its field.
2. synonym for pseudoscience.
CCC is fringe in the first sense. It's not my or other layman job to join discussion or have an opinion. We can just watch the discussion. It does not seem to make sense to other physicists. The observational parts are also questioned. https://www.preposterousuniverse.com/blog/2010/12/07/penrose...
> is your first point "you need mass to have time. Massles particles don't experience time" a fringe concept?
The way it is stated, yes.
A correct statement of an innocuous truth of relativity is that the concept of "elapsed time" doesn't apply to massless particles at all. It only applies to particles that travel on timelike worldlines, and massless particles travel on null worldlines.
However, that correct statement does not imply either that massless particles don't experience time, or that you need mass to have time. Null worldlines in different directions can be used to define time.
In view of my other comment, I should make clear that I don't actually think the first bullet is necessary to Penrose's model. If "time passes" during the period after all black holes have evaporated and before the cosmology "recycles" itself, that does not seem to me to be a problem for the model. (Which of course doesn't mean the model is necessarily right, just that this particular issue doesn't seem to me to be a problem for it.)
The first point is a simple consequence of Relativity, and is as non-fringe as it can be. In fact, there was a nice youtube video about it recently… here: https://www.youtube.com/watch?v=HU6t8QvGZmA
Particles with mass decaying to massless is pretty fringe. To my knowledge, there are no mechanisms for electrons to decay (except for meeting a positron, I suppose).
According to Hawking, they will all eventually evaporate. For supermassive black holes speculated eventually to swallow galaxy superclusters, this will take on the order of 10¹⁰⁶ years.
I think the lack of any remaining mass is exactly what leads into a timeless infinity (heat death), which is then, from a reference point outside the universe, indistinguishable from an infinitesimal singularity, which can then kick off a new big bang.
1) so much non-fringe it boggles my mind. This is basic.
2) let's say 50% fringe, at most.
3) 25% fringe. Most of the relevant science buys into this, and not just b/c it sounds nice.
4) Reasonable conclusion, if the stated theory was true. 25% fringe.
5) This is a multiplication of uncertain conclusions, so let's go with 75% fringe.
6) A conclusion of 5), which would be detectable. At most as much fringe points as 5), since it can be falsified.
There's always wikipedia to grasp basics, and then there's Ethan Siegwl with Starts with a Bang, and if you're still interested there's a lot more including astronomy and physics papers. astronomy.stackexchange.com, physics.stackexchange.com and even your local university.
Edit: Since this has been downvoted, I'm genuinely interested in the reasons and especially the facts you obviously have which I don't. Please let me know where I was wrong!
For someone who found f=ma challenging (especially when it got to general motion and tensor math), this page of comments commits me to days of Wikipedia and pulling down Hawking's books from my bookshelf backdrop, yet again. Thanks, folks.
I don't get the heat death theory. Particles can move away from each other without end. The universe gets wider and wider meaning sparser and sparser. So you could imagine that at infinity there would be nothing in it. But, you can never reach infinity, that's the definition of it. So the universe never becomes "empty" even if it expands without ever stopping.
The basic idea is that in the end, all matter is in black holes, the rest is radiation. You need matter in order to define space, so if there is no matter, space or rather the original space doesn't exist anymore.
You can contract all the radiation (that doesn't have a notion of space due to the lack of matter) into a new point and start something like a big bang.
I think of it as redefining the space that makes the universe, rescaling the size of the whole universe. Anyway, that's my personal take on this so far.
That's my understanding as well, but there are some well-established features of the universe that make this more plausible.
We know that our spacetime is in anti de Sitter space which is a type of hyperbolic geometry. In this geometry, infinity can be thought of as the edge of a sphere containing our universe.
Matter is equivalent not only to energy, but also to frequency and wavelength. Once all matter decays to photons and those photons hit infinity, there isn't anything remaining in the universe that provides any sense of scale. It could be argued that the concepts of frequency, wavelength, time, and length cease to exist.
Since you no longer can measure scale, all those photons at infinity look very similar to the photons in the primordial soup of the big bang. Furthermore there could theoretically be information transfer as the pattern of photons on the sphere vs. the pattern of the primordial soup (visible today as the cosmic background radiation) would be the same.
It is only from the reference frame of some physical observer inside the universe that it takes time for them to reach infinity.
From the reference frame of a photon, not only does it instantly arrive at infinity, but infinity and its original position one in the same since length is contracted to zero.
No explanation on how "expansion of space" fits with it. Did space expansion reverse and collapse back at one point? To restart their expansion after a new Big Bang?
No, the conformal cyclic universe is weird in that there is no contraction that actually happens. Things keep expanding out into forever and that’s part of why the CCU works.
What happens is that the one universe becomes really boring-looking when you look at it from the perspective of one universe, so you use one of your mathematical freedoms (that everything looks the same under a conformal mapping) to shift your perspective. Conformal maps are their own interesting field of mathematics, let me tease you by saying that the usual Mercator map projection has this really nice property that if you zoom in on the map to get a "correct" close-up of any city, you get something that looks angle-for-angle correct at the city scale, you just have to zoom in less on, say, Bogota than Reykjavik because the poles are zoomed so much larger than the equator. By choosing other position-dependent scale factors you can instead get, say, the stereographic projection which has the same basic rule but now which direction is "north" always points to the center of a circle and now Bogota is bigger than Reykjavik, but they still both look "correct" locally, they are just out-of-scale at these longer distances. These angle-preserving deformations of space are called conformal maps. Actually, if you accelerate in any given direction the stars you see all crowd in towards the direction that you accelerate, but they do it conformally. So like the Pleiades will still look to first order like they look now as they squish in towards the direction you are going.
Anyway, there is a subset of physics called quantum field theory and a subset of this subset is called conformal field theory and during the heat death of the universe the QFT becomes a CFT and so you get this freedom to apply conformal mappings, the physics doesn't care and the equations stay the same. Penrose's idea is that if you choose the conformal mapping just right this heat death looks suggestively like a Big Bang for a different universe. So maybe from the perspective of this universe, the universe is ending in a heat death off at infinity, but maybe there is a perspective of a different universe where that same homogeneous ending was actually a homogeneous starting point. You redefine things like "distance" and "time" and stitch together the infinite future of one universe with the Big Bang of another. But like that other universe does not ever itself contract, the contraction comes in this redefinition of everything meaningful. The words of the old eon cease to have meaning and you use the words of the new eon.
If there is no matter and nothing that has any attributes depending on time, then distance and duration becomes meaningless. In conformal geometries scale doesn’t matter so the incredibly immense and microscopically tiny are geometrically equivalent. There’s no contraction, rather a kind of re-scaling.
I'd like to know if the idea allows for the transmission of information from one aeon to the next? If so, how much information? Enough to write a short message in ascii, or to encode a vast library of the most exquisite artifacts discovered in a search whose genesis lies in the infinitely distant past? What about the mind state of a creature, and instructions for its reconstitution? Is it possible to as it were, throw oneself into the next aeon?
Yes, see the "CCC and the Fermi Paradox" paper [1] by Gurzadyan and Penrose himself talking about exactly that.
You can also look into "Information Panspermia" [2].
Relevant bits:
> "From our own limited and relatively extremely
primitive perspective, much more promising would undoubtedly be electromagnetic signals (although neutrinos just
conceivably present us with another possibility). The conformal invariance of Maxwell’s equations allow us the possibility of such signals surviving the crossover from one aeon to the next-provided that the wavelength is long enough
to avoid excessive scattering by charged particles in the early stages of the subsequent aeon."
> "Alternatively, there is the idea of information panspermia, introduced in [12],
and attributed as ”Solution 23 to Fermi paradox” in [2], i.e. the propagation of the ”life codes” by the use of such
signals, like the bit strings of human genome and of other species of terrestrial life"
If he means there was a time "before" time, wouldn't we need some metatheoretical notion of time to even state that? Like how can we state that in our system if our time begins at the big bang? I don't get it
That is part of the definition I suggested. If we knew it was there, then it would be part of our universe. It's a one-way valve on knowledge but I still think it is useful to define it.
There is plenty of work to be done on the definitions. Should we like to, we could have a more rigorous natural language regarding observables by defining a boundary for where the physical universe begins and ends. Shrödinger's wave function does not appear to be part of the physical universe but yet we have an odd kind of observation of it in the form of experimental verification of theory. The space of theoretical physics then becomes part of the greater universe.
I think Penrose's ideas warrant more precisely defined language.
I'm not sure! I have thought about it a lot though.
On one hand yes, it feels like it should be the same. On the other hand, it is not parsimonious to create another space when there is plenty of room left in this one.
Should we define another universe as something which never has and never will interact with our universe? If so, anything we can observe of seemingly another universe is in actuality part of our universe.
The topic seems like it could use a consensus about what the words it uses should mean and not mean.
> If so, anything we can observe of seemingly another universe is in actuality part of our universe.
Yes, this is how I would interpret the definition of THE UNIVERSE. My personal interpretation of "another universe" would be something like- a multidimensional vacuum populated with matter/energy that currently exists from our inertial frame of reference, and there is nothing linking our own sparsely populated vacuum to this other universe. i.e. if you can observe it, then it's not a different universe. As Penrose states, this is merely an earlier version of the same universe, which existed before the Big Bang.
Here is a different prediction, a timelapse, of the fate of our universe (as told by Brian Cox), which assumes the universe will continue expanding...
I have this idea that the singularity inside a blackhole is a tiny point in space with almost uniform energy distribution. From the perspective of the tiny space, it is not tiny at all, and could actually look like a big bang locally.
Anyone know how virtual particles would fit into this model? If these particles pop in and out of existence even for small amounts of time out of nothing, then it’s impossible to have a universe just full of massless particles?
Numbers aren’t really that useful when it comes to advanced geometric transformations like thus. If you’re interested in the theory behind it there are quite a lot of videos on YouTube about it, from pop science interviews to presentations at conferences.
I don’t understand how we can observe something (“warm spots”) that by its construction should be unobservable. If it’s observable, doesn’t it exist in normal time/space?
I like a big crunch way more than a big rip or a heat death. That means things never really end. A heat death or a big rip sounds like there would be an ultimate end to everything. A cyclical universe means that there would always be life and that there always has been life, no?
I'm jumping off the deep end here, but it's funny that Hinduistic mysticism has come to the same conclusion (the universe iterates through cycles). It says that we're currently in the 84th iteration (if I'm recalling correctly).
It might be bad form to nitpick a nitpick, but whether a statement is a speculation depends on how much information it is based on. We don't know how they came up with the number, so we don't know if it's speculation. We can't say it's not speculation for the same reason. Now, if I were to say that this anecdotal data-point is scientifically significant, that would be speculation.
Proof doesn't really matter. Most theories you have in your life are unproven. Scientific hypotheses should be falsifiable which means unproven. There are dozens of comments in this section making unproven claims that you don't seem to have taken issue with. You just don't like this one in particular because its associated with a religion.
They should be falsifiable and they should make predictions under various conditions and be right about them for the hypothesis to be considered a theory. Does this have them? Usually successful hypotheses have a body of work behind them, say like Newton’s principia or Darwin’s origin of species. They usually have corollaries and extensions which extol the same truth in various ways. Rest is opinion/speculation - just because it is religion I won’t give it a free pass.
If you make thousands of random claims, it's only natural some of them will end up being true. It doesn't mean Hinduism has any predictive power. I'm not saying it doesn't, I'm just saying we cannot determine that from this one data point.
I think it's best to take this stuff as stories, as in something that invites you to suspend disbelief and takes you places. There isn't a need to feel reserved about believing it, because you just explore it and then put it down. I find that mythology stimulates the naive aspect of my mind, which feels good and nourishes creativity.
I’ve also found it very useful to be able to explore the various mysticisms with an open mind of disbelief, because I find useful patterns that lead me to new ways of thinking about the world I do believe.
One of the things I like about metaphysical myths is that when you learn about more of them you realise that you had unconsciously come to believe myths that you got from your environment when growing up. It can be a big deal to, for example, realise that you've been thinking about the universe as something that has a beginning and an end, because then you can consciously evaluate whether you want that belief. What story you tell yourself about existence is a big deal.
We have a universe that expands and expands, and all mass decays away, and in this crazy theory of mine, that remote future becomes the Big Bang of another aeon.
Hawking Rings, Delayed Choice Double Split Experiment and Fermi's paradox imply that the universe came into being and time started when a quantum superposition was in a place where if collapsed would create humanity.
These physicists today can get away with making the most outrageous claims and everyone swoons around them without challenge. There is no evidence of a previous universe to our own. Period.
