Big Bounce Simulations Challenge the Big Bang
quantamagazine.org
quantamagazine.org
Every time cosmologists looked, the universe got bigger and suggested growth. The big bounce at no point in history ever looked right. Moreover, the big bounce kicks the bucket down the road. It ultimately has the same metaphysical issues.
I find the reasoning poor as well. "I don't like inflation" != "The universe ends in contraction". Yes, it's proven difficult to explain CMB smoothness, but this doesn't mean the big bounce is a better candidate than other non-empirical ideas.
I'm confident truth will be far stranger than big bounce fiction.
- Infinity: There is no beginning and something always precedes the 'current' step (e.g. the Big Bang occurred out of something)
- Discontinuity: There is a beginning. Everything suddenly started out of nothing.
While both options are hard to grasp for the human mind, the second one, which is the standard Big Bang also sits very uncomfortably with Physics' concepts and is the more 'disturbing' of the two. I think that's why people have been looking for alternatives to the standard Big Bang theory.
Infinity, is still unfathomable but at least it is easier to fit Maths and Physics around.
Even adding God to the mix still leads to these 2 options, because if the Universe was created by 'God' it implies that the Big Bang is not the beginning and that something (God) pre-existed. The idea that we might be in a simulation is equivalent to a creator God, just more hi-tech.
It really seems to me that these alternatives, infinity or discontinuity, are inescapable.
Arguably Maths requires this same discontinuity due to Gödel's Incompleteness Theorem. Consistent axiomatic systems require a Gödel sentence that is unprovable in the system; it requires a logical tautology or else your system will contain an infinite regress.
I think of a logical tautology as a kind of "something from nothing", but I suppose that is debatable. The implication of this property of axiomatic systems on reality is also debatable, but wouldn't any system we come up with to describe reality need to abide by these same rules?
I don't see the connection between these two statements. Yes, in a consistent system with a finite description, a statement in that system which can be interpreted as "the system [description of the system] cannot prove [this statement]" cannot be proven (also, where "can be interpreted as" is taken to mean the sensible thing that it should mean) (though, sufficiently weak systems can have languages incapable of expressing such a statement) .
But the second part of that sentence, after the semicolon, appears to be talking about something else? It seems like it is describing the Münchhausen trilemma , except applied to mathematical proofs, and giving an argument that a system needs axioms (and/or rules of inference). While a system of proof does need axioms and rules of inference in order to conclude anything, this is not because of the incompleteness theorem.
The two do not seem particularly connected to me. So, I don't see why you connected the two statements with a semicolon.
Perhaps I misunderstood what you meant by the second statement in the sentence?
Also, when you say "logical tautology", are you talking about purely logical tautologies, or are you talking about axioms? The way you are using it makes it seem like you are talking about axioms, which I wouldn't call logical tautologies. But maybe you do mean what I would mean if I was to refer to "logical tautologies"? In that case, uh, I don't think logical tautologies are all that much of a foundation?
https://plato.stanford.edu/entries/eternity/#DiviTime
See also:
It's similar in some ways to the concept of block time, in which there is no progression of time. The universe simply exists and the perception of the 'present' is an illusion. Similarly for Minsky the perception of reality or existence is an illusion.
Labeling something an "illusion" like that seems like a massive cop-out, made by a mapmaker to avoid confronting the fact that their maps don't fully represent the territory. Fossils weren't illusions, and I don't think the present or existence are illusions either.
I suppose if what you mean by "reality" is "perception", and if what you mean by "illusion" is also "perception", then what you mean by "reality" and "illusion" would be the same thing, namely, "perception", but, I don't think that's what you mean?
But even these models of an objective reality that come from quantum physics are not direct, as you had to build them in your mind through information you received through your senses, so this sense of an objective reality outside of your mind is also an illusion.
That’s not particularly relevant to a discussion about science and the Big Bang. In science we assume that multiple measurements by multiple people of the same phenomena gives us a good idea of the behavior and whether it matches our models. Our models will likely forever be incomplete but throwing our hands up in the air and trying to say “yes, but do we really know that” doesn’t seem helpful.
Now, I don't mean to say that you can't define senses of talking about "most sets" or "how common are sets with a given property". I believe some people working with category theory stuff came up with a sense in which the "amount" of finite sets (up to bijection?) is Euler's constant, e. So, I don't mean that you can't come up with a sense of "most sets" in which it is true that "most sets are infinite" or even a sense in which "almost all sets are infinite".
But you would have to both describe the sense in which you mean that, and also argue for why we should consider that to apply to our intuitive notion of what is "likely" to be true of the universe in which we live, rather than some other sense.
Also, the universe having existed for a finite amount of time, doesn't really mean that the, what, set of points in time (in a given reference frame) is finite. Like, maybe time is discrete, but afaiu, we have never observed anything that strongly suggests that it is, and everything we've seen is compatible with using, and we usually do use, mathematical description of which are based on infinitely divisible time (though, there are some things about the planck time and whatnot.) . So, if time is infinitely divisible, the amount of points in time would be infinite, not finite. So, even if one successfully argued that it be "unlikely" that the set of points in time so far be finite, it doesn't seem clear that the amount of time so far shouldn't be finite, because the amount of points in time could be infinite in cardinality while being finite in measure.
Even if you wanted to argue that the cardinality of amount of points in time should be at least [any cardinality you want], I still don't think that would be a problem, because the class of Surreal Numbers have ordered subfields of arbitrarily large cardinality (as well as having arbitrarily large cardinality in any interval), and I don't think we could do anything to really distinguish between points in time being infinitely divisible and like the real numbers, vs infinitely divisible and like one of the larger subfields of the surreal numbers.
You would have to argue that it be unlikely that something like the measure of the collection of points in time so far be finite, not just something like the cardinality of the points in time.
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> When you look at the axioms in first order logic the requirement of negation is suggestive of the idea that “nothingness” (i.e. something preceding a finite set) is a logical fallacy.
I cannot get any reasonable meaning out of this. First order logic doesn't even have a concept of "finite"/"infinite" or "finite set". I'm pretty sure this is just nonsense. Having the universe of discourse be empty is a totally valid model of first order logic.
Also, I personally prefer to reserve the "fallacy" to mean "a step in an argument which is not valid", and therefore would not apply it to a concept.
Also, "something preceding a finite set" does not, in my mind, at all correspond to "nothingness", so I don't understand why you equated the two.
The question of "why is there something rather than nothing?" is still absolutely valid, but my mind's open as to whether the answer necessarily involves either an infinity or a discontinuity.
Even if you assume that space-time has always existed, an infinity scenario, (though you then have interesting questions on the nature of time if nothing exists) you still need to explain the existence of energy/matter, which will still be either an infinity or a discontinuity scenario.
God exists outside time and space (is infinite) and created the universe by calling a potential into form.
Which of course still has the issue of infinity: where did God come from? And even: what does it mean to not be limited by time and space.
According to this[1] 'eternal' is now ambiguous enough to suggest either "outside of time and space" or "persistent through all time."
On nested-simulation views I suppose it becomes necessary to clarify which clock domain(s) we are talking about, in terms of persistence or time.
Off topic, but I always found it interesting that some people who otherwise reject the idea of a God latch onto that one. At some point it's all kind of religion.
Anyway, if Universe is infinite, it is infinite in all 4 dimensions. It cannot be infinite in just 1, 2, or 3 dimensions.
I mean... with the scale of the timelines being discussed, that makes sense.
They aren't suggesting that the expansion and contraction happens within thousands of years but billions of years.
I don't think there's anything dogmatic about keeping an open mind. If you want to see dogma at work, see a reply to another comment of mine here where I'm ranted at about what is or isn't 'Scientific' and questions being 'non-scientific' simply for pointing out that the Big Bang isn't a complete model of the origin of the universe.
There are a lot of unanswered questions in this area and it's far from clear to me at least how they will be resolved, but I'm very excited to find out. I just don't think mud slinging about dogma and being non-scientific is going to help with that.
However, I must say that once P. Steinhardt gave a seminar in my department, and he debunked two famous "predictions" of the inflationary theory (flat universe, scalar index n_s slightly less than ne) showing that papers published in the 90s claimed that inflation predicted "naturally" an open universe with a scalar index larger than one [1]. He used this to stress the fact that inflation can predict almost everything. I must say he sounded very convincing, he wasn't claiming that inflation is false, only that it is far from being a well-established theory, and that other hypotheses must be considered as well.
[1] http://physics.princeton.edu/~cosmo/sciam/index.html#facts
"The universe" is not an answer because information about causal events prior to a configuration space capable of recurrent relationships is inherently unrecoverable not non-existent. (Unobservable =\= causally impotent.)
This is why people are getting tired of scientism. Instead of being unbiased, some so called scientists are putting dogmas ahead of their observations and pushing for an agenda under the guise of science.
The force from the big bang was imparted in an instant yet gravity is a constant force. IANAP but surely at some point the accumulative force of billions/trillions/... of years of gravity overcomes the force imparted by the big bang and the universe compresses into a singularity again?
I'd really appreciate someone explaining why this isn't obviously the case.
To say it in another way, the energy used to expand the universe today is not only the initial force imparted by the big bang but is added to as part of quantum processes in empty space. However as the universe expands, the amount of matter (dark + luminous) does not increase so the proportion of gravity/matter to dark energy (the force that accelerates the expansion) is getting lower and we get an acceleration.
These observations exclude the possibility of a "big crunch".
Disclaimer: I am a statistician not a cosmologist but this is how I have understood it.
An interesting thing happens.
When you tear a quark away from it's antiquark, you get two quarks. The energy is equal to that required to bring another quark into existence. At this point, the rate of expansion is so vast that every quark in the universe has been forever isolated from one another, and then each bursts into a sea of high-energy quark-gluon plasma. The massive energy of expansion is rapidly consumed generating these quarks, and then the expansion slows, never stopping, but continues at a much slower rate.
Wait... we've seen this before. A quark-gluon plasma, rapidly expanding from a single point, in a universe isolated from all others.
Only expansion is required to generate new universes, forever.
Space is expanding.
Objects far apart are traveling away from each faster than the speed of light. Or more that the space between them is expanding faster then the speed of light. So those objects will never have any sort of interaction.
Only ways around this if space itself start contracting. (No known way for this to happen).
Or somehow the universe is a big circle, and going far enough brings you back to the starting point. Negative curvature.
We don’t have any good theories on this. Some highly interesting ones that move the problem up a level.
For Example one theory is our entire universe is inside a black hole created from the remains of a four dimensional hyper star.
The math seems to work. Soo cool. But then where does the hyper star come from?
It’s “turtles all the way down”, is the thought to lot of the best theories.
Or everything is a simulation, again math kind of works. No direct evidence, but neat idea. But who’s hosting the sever that’s running the universe.
Something from nothing problem is a real trouble maker.
I was also under the impression that an expansion of space would just reduce the gradient of the gravity along that space and not inhibit its propagation.
If like a bubble space has some form of surface tension then would there be a point that it can no longer expand? Gravity could then become dominant and force the contraction. -edit-> I guess that wouldn't contract the space though just the matter?
I promise I'm not being pedantic or contrarian for the sake of it but to further my knowledge, thanks for your input!
According to out current best cosmological model, Lambda-CDM (which, admittedly, is mostly a phenomenological model for things we only half understand, but still describes our current observations better than any competing model), gravity used to be the dominant force in the universe when it was smaller so that the masses were closer together until quite recently. But now it looks like the expansion, the "Lambda" term in "Lambda-CDM", the cosmological constant of general relativity, has become the dominant force in the universe, and the universe is slated to expand ever faster.
It could start to contract if Lambda were closer to zero, but it currently doesn't look like it might move there. But then we don't know why Lambda it there at all and what causes it not to be zero in the first place, as everyone expected it to be until about two decades ago (Einstein himself thought of the introduction of the term into his theory as a blunder, as it would obviously be zero in any sane universe.)
Maybe at the border of the universe there's a crunchy layer of mass that at some point gravity force will win over expansion.
Space is infinite and increasing.
Matter is fixed and static.
So a bigger infinity divided by a smaller infinity.
Which means density is heading towards 0. This is heat death of universe.
Now since dividing infinity by infinity is nonsense, this a sign our understanding is incomplete
Its programmers all the way up!
But really, awhile ago I settled on the belief that its very possible we're in a natural simulation. Natural, as in, the same way that plants are simulations of L-Systems or in particular the same way my GPU once spat out cellular-automata-like behavior in a glitch.
If we are in a simulation, we've got no prior on what the world "above" us might be like. Oftentimes I see the theory shot down with "Our universe is too big and complex, theres no way any computer could be big enough to simulate it!" which is valid if assuming scale and physics anything like ours. But that's not a reasonable assumption here. It could be that the computational power of a cheap smartphone in the above world is similar to what a supercomputer the size of Jupiter or even Sun or any scale really for all we know. But that still assumes a programmer. If computing is done a lot in the above world at that sort of scale, our universe could be the result of a hardware glitch. That specific scenario may be quite unlikely, its just the extension of the GPU creating cellular automata by chance that I mentioned earlier. There's many other ways for algorithms of simulation to naturally emerge from reality just existing and things within it creating new sub-systems, which from within such a system, appear to be "something from nothing". So in a sense, it seems most likely that whatever the case is we are likely not one the "first layer" of reality, we are "simulated" within sub-layers. So then the interesting question is not how did this particular something come from nothing, but how can anything come from nothing, in the very first place, ever, at all? Once something exists, while scientifically we'd want an answer for how to get from there to here, its just a matter of what exact process that is.
Big bang only makes sense to a particular energy/time/space limit. All the energy that came to be all the universe already existed. What happened 'before that' doesn't even make sense. I was told that 'creation' type language is a misunderstanding of the big bang.
Is that not still the way it works?
The quantity of nodes in a branching tree of causal events can grow larger without time or space if there is no reccurance for any given state to be compared to another.
From the "gods eye view" the tree "grows" even if there's no internal information which can be used to recover any space/time prior to reccurance.
We have wiggle room for planck epoch because that time was after singularity, meaning that we have information from that time (however little of it is left).
Closest we got to science here is by extending the time and space axis across the diagrams point of origin. This is where idea of singularity being in heart of higher level universe black hole (or past universe’s collapse) comes from. Its inpossible to verify black hole idea due to deletion of information, but collapse/crunch should be observable in distant future of the universe. Perhaps dark energy still has some tricks up its sleeve?
https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology#Emp...
The fact that Penrose’s work is possible and ongoing is proof enough that scientific discourse on the matter is open and possible.
Science never has final say on what’s impossible. Until (if ever) we have a grand unified theory that perfectly coheres all we find and ever find, you cannot claim to know of an impossibility.
For example, an easy proof you’re wrong would be simulation theories. In that case, the Big Bang is just a sub-simulation inside a bigger universe. Can you prove we aren’t in a simulation? If not, then you cannot make any claim about how it’s not scientific to talk about before the Big Bang. We just don’t know, so taking the positive is an error.
In context of scientific debate, no Simulation theory exists. Only hipothesis, and a very weak one, considered it’s not falsifiable. Hence its treatment as curiosity and thought experiment by scientific community.
Your hypothesis needs to meet some requirements in order to be scientifically viable to research. You cannot throw out scientific method out of window because it appears „close-minded” to you.
Until proof appears that singularity is not errasing information, scientific approach is to find a proof that there’s no singularity as threshold between old and new universe within a cycle. And argument for that is currently based on interpretation of some features pf cosmic background, which is scientifically debated.
Personally, I’m stumbling on understanding physical fields. This looks like another field is being added, which is nice in some sense, but why do we have the number of fields that we do and what conditions are needed to create/sustain physical fields?
It's only an issue if you think about space and time as separate things. I find it makes (a little) more sense when you understand that time is a function of spacetime. Therefore if you're happy with space not existing prior to the big bang (which people do seem to be OK with) then automatically time didn't exist either, and hence 'before the big bang' ceases to be a problem.
“it just did” has never been a satisfactory answer inside of churches or seminaries. That is why almost all the metaphysical discussion in these areas of human thought are around why we exist (in human terms).
“it just did” has been a satisfactory answer outside of churches or seminaries. This is why almost all discussion of why there is something rather than nothing in secular academia is ‘meh, impossible to know, don’t worry about it’
Think of time as "it prevents everything happening at once". Before there was time, nothing prevented everything happening at once, without space nothing prevented everything happening in the same place, so everything happened at once and in the same place. That everything happening made so much noise that it created space and time in a very big bang.
I suppose the question comes to, what is time? I imagine "time" to be a degree of freedom through which something can change. I understand some see time to be related to entropy, and that it's an emergent property of this thermodynamic property but this seems too limiting. It would seem entropy is more-so an explanation for the arrow of time, but not time itself.
If time is defined as the dimension through which something can change then should time not be fundamental to any cosmological theories that extends beyond the Big Bang?
The same is true of "space" for the same reason. A causal network without reccurence (a tree) has no way to compare objects since there are no horizontal relations and it cannot "look" at backwards relations.
A non-reccurent causal tree has multiple instances of "here" and "now." But without anything to compare a given here/now to the concepts are internally meaningless.
Not "something". Everything. Like "What is possible to happen? Everything is possible". If you can't divide that possibility by time period, everything possible will happen with probability of 1. How improbable is that universe will happen during 1 trillion years? Very improbable. But if you can't tell in how many years universe will happen, it just will exist.
> but what does that mean for this to "happen all at once"
If you don't have time to make difference between two things happening one after another, they will happen both at the same exact "time".
> If time is defined as the dimension through which something can change then should time not be fundamental to any cosmological theories that extends beyond the Big Bang?
The problem is, time depends on local state of space. More energy/matter in a chunk of space means time is slower relative to other chunks of space. So when you try to go into past with mass in chunk of space increasing into infinity, that time notion breaks.
There is no timeline by which to order cause and effect.
I would argue that the second sentence implies the first isn't true. You can't imagine that there is no time if you're saying things can't happen without time. What I said doesn't mean things can't happen, it just means they happen in a way that doesn't require time to exist (which could be everything happening in the same irreducible instant, or in any order, etc.)
How does this notion of time become decoupled from space?
One way I imagine it is that "time" as a concept encapsulates at least two properties:
1) The degree of freedom (i.e., dimension) through which things can change; and 2) The unidirectional flow of causal events
Relativity seems more concerned with defining time in terms of casual events (e.g., event horizons) than its dimensionality. If we define "fundamental time" as a dimension that allows for change can it then be decoupled from space?
ds^2 = dx^2 + dy^2 + dz^2 - dt^2
Thinking in terms of 3 dimensional euclidean space, this makes sense. If you fix your 3 dimensional coordinate system and pick 2 points in space, you can have:
ds^2 = dx^2 + dy^2 + dz^2
Simmilarly, in the 4 dimensional spacetime defined by the metric:
ds^2 = dx^2 + dy^2 + dz^2 - dt^2
The only complication here is that rotating your axis under the Lorentzian metric require the Lorentz transform; whereas rotating them under the Euclidean metric requires the Galilean transform.
The coupling described here involves no notion of causality. Nothing in the metric prevents a path from traveling in both directions along the time axis.
Further, if two events have are separated by a negative ds^2, then all observers will agree on the order in which they happened, though they will not agree on the length of time that passed between them, or the relative positions.
Note that I'm using your version of the equation for the definition of ds^2 > or <0, though in general I've seen it expressed the other way around, ds^2 = dt^2 - (dx^2+dy^2+dz^2).
We can distances with ds^2 < 0 timelike, and ds^2 > 0 spacelike. We say that events with a spacelike cannot influence each other; but there is nothing in relativity that requires that (unless you introduce causality as an additional assumption, which we generally do).
This gets more messy in general relativity when you allow for large masses (read. Black holes).
In the case of a non spining black hole, we spacetime is described by the Schwarzschild metric. Expressing this metric in spherical cordinates, you find that when you pass the event horizon the sign of dt^2 and dr^2 flip, where r is distance from the singularity. This means a "timelike" seperation means that events are closer to each other in the time dimension; and events with a "spacelike" seperation are farther from each other in time. That is to say, "time" behaves in the way we think of as "space", and "space" behaves the way we think of as "time".
Actually, time does not exist. It's simply the rate of change of matter.
Intrinsically information about prior contingencies are unrecoverable "before" recurrence. But unrecoverable is not "non-existent."
There's another way to approach all this. Start by asking: what's the one thing I know for certain? It's hard to say any more than it certainly seems like something is happening. Investigate this sheer fact of "seeming." See what the seeming is like before you apply any metaphysics on top of it. What happens when you do this extremely precisely?
Suppose that the correct metaphysics is that you are ultimately the primordial ground of being, that (paradoxically) weaves itself into apparent realities. What we think of as physical reality is just one instance. It transcends parameters like time and causality, but can give rise to them of its own will. Being the primordial ground of being, nothing logically prevents you from knowing this ultimate truth directly and unequivocally (unlike if you were really just a human).
As it so happens, the preceding paragraph describes how you would (re)arrive at this knowing. Or at least, that's what's suggested by various mystical traditions. As far as I can tell, there's definitely something to it.
[1] "There is no way to distinguish between the scenarios by collecting new data. What we’re left with is our choice of prior credences. We’re allowed to pick priors however we want. [...] We have every right to give high credence to views of the world that are productive and fruitful." —Sean Carroll, The Big Picture (p.91)
For whatever reason, it makes more more anxious than it should. The concepts involved are so far removed from my brain's understanding of reality that it makes me uncomfortable.
Usually it is nothing to worry about, except when you get obsessed by it and it starts to control aspects of your life because you build a worldview around it or try hard to avoid it or explain it away: then it is called an existential crisis. But what it really means is that the mind gets overwhelmed by the fact that the universe is orders of magnitudes more complex than what the self has ever encountered in our daily lifes. Our brains have evolved so that bipedal apes that migrated from forests into the steppes can survive and cooperate in groups. It was never meant to be confronted by questions of this dimension, but yet here we are.
You can make your peace with it, and embrace it. It can also be a source of endless curiosity, spirituality and creativity.
Somehow the perspective of my life just being a tiny sparkle in the grand scheme of things would render any stress moot.
There is no reason that a superintelligent AI cannot do the following: create superintelligent theories about the universe (using superintelligent intuition), create superintelligent tools to prove its superintelligent theories, leading to superintelligent empirical observation, ultimately producing the answer to the question of our existence far faster and far more eloquently than is predicted.
Existential anxiety isn't per se about the relative size of self to the world but more about the inability to grasp and control the understanding of it. Pretty much everything living strives to "control" things, and in the case of human beings this applies to mental things too. Controlling things on a mental level is usually about understanding them, not necessarily about bending them to our will.
Anxiety is tied to a difficulty in dealing with perceived lack of control (over others, over our emotions, over the future..), and existential anxiety is an example of anxiety when it comes to existence. We simply don't know enough to say something that cements control.
Thankfully one of the coping mechanisms is humour, so I'll leave the reader with the very well known Douglas Adams bit:
“The story so far: In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move.”
I decided to accept the Douglas Adams perspective: In an infinite universe, an infinite number of seemingly improbable things will inevitably happen, including a random number of particles ejected from astronomical explosions collecting together in one spot in such a way and for just enough time to create life as we know it, and for some of that life to think, "Why am I here?", before entropy rips all of it apart again a cosmic blink later. We exist because in an infinite universe, all things that can happen will happen, including you. There's even a universe in which a god did in fact create everything... which is an interesting question: How do we know if we're in that universe or not?
https://en.wikipedia.org/wiki/Boltzmann_brain and https://en.wikipedia.org/wiki/Quantum_suicide_and_immortalit... ?
That's fantastic.
Not the dread of an insignificant existence, rather, the dread of an unending existence.
I always wondered whether other people experienced this too, now I know. Thanks!
I take solace in some way that I am not alone in this and that there are other groups of trillions of atoms somewhere else in spacetime pondering the same questions with the same intensity.
Like you're about to touch something that could cause everything to blink out of existence.
It actually causes physical discomfort and an increased heartrate and rapid breathing, like you need to turn back, NOW.
If you approach with a healthy nihilistic attitude, it's just cool stuff but doesn't matter(because nothing matters and as a nilhilist that's OK). But if you're chained to upholding or championing something, the existence question may become an enemy, one that is so hard to dismiss that it drains you.
Curiously, Latter Day Saints (aka Mormons) have taught for over a century that essentially the Big Bang theory is incorrect and that matter has always existed and that when the Earth was created God simply "organized" existing matter rather than conjuring something out of nothing.
Putting aside their other beliefs I thought this was an interesting curiosity in this context.
Growing up LDS there was never any existential angst as I became more educated and there was never a need to overcome any cognitive dissonance as I learned evolution or cosmology- the baseline belief is a very sci-fi one of the first super-consciousness (God) taking upon itself the shaping of spiritual (dark matter?) and then physical matter and making pathways for other intelligences to master the same. No ex-nihilo involved.
Even if the LDS specific conceptions have all the details wrong, the overarching idea is completely plausible.
Why is a universe that has always been in existence, cycling through different states, any more sensible than one that pops into existence only to ultimately fizzle out? Both require the presupposition of some kind of uncaused system. Gathering evidence pointing toward one or the other is key.
I do think that the Big Bang maps better to Western religious cosmogony (matter was created ex nihilo) and Big Bounce to philosophical materialism (matter is the fundamental substrate of the world), but that shouldn't bias a scientist against the Big Bang.
Anyone here able to weigh in on that?
Why can't it be Everything?
i.e., instead of imagining the Universe as a white dot on a black canvas, how about thinking of it as a black dot on a white background?
The big bounce avoids this particular problem.
Although I guess that makes sense. After all it's spacetime, not space. So if the expansion rate is higher than the speed of light, then you don't have the black hole problem.
> Over billions of years a contracting scale factor brings everything a bit closer, but not all the way down to a point. The dramatic change comes from the Hubble radius, which rushes in and eventually becomes microscopic
All the matter of universe at a microscopic radius? That doesn't avoid the problem.
With this continuous (eternal?) contraction and expansion, I'm reminded eerily of a heart beating, or something breathing...
As far as being too big, that's not quite it. Everything is moving away from each other because of the big bang, but astronomers realized that hey, gravity should be slowing that down. So they tried to measure the deceleration of the expansion of the universe. Instead they found it's accelerating.
There's a lot of theories as to why, but right now it's just called "Dark Energy" because no one really has a full understanding of it. Space itself seems to be stretching out, becoming larger.
Will the acceleration of expansion continue forever? Maybe someday it will slow and reverse? No one is sure yet.
Therefore we can either: a) Fit the models to fit the data. b) Invent more physical phenomena to make it fit the data (quasi particles in physics).
There is nothing wrong in doing that, but there is severe arrogance of saying that "the bing bang happened" where in reality we just have a hypothesis.
And even "the most widely accepted by CONSENSUS" hyptothesis doesn't make mean is actually TRUE.
It's perfectly fine to make new theories, but at the end of the day we simply don't know enough: and yet the mainstream/every kid believes in the the bing bang to the extend as religous people believe in God.
Here are some PBS Space Time videos on the subject:
Why the big bang definitely happened: https://youtu.be/aPStj2ZuXug
Did time start at the big bang: https://youtu.be/K8gV05nS7mc
Whats wrong with the big bang theory: https://youtu.be/JDmKLXVFJzk
“In the beginning, there was nothing, which exploded”, now, a lot of non-scientists like to repeat this statement, but no credible scientist has ever said this, nor believes it. So its unfortunate that this statement is used to deride the big bang theory. The big bang describes a series of events that happened to the universe following its existence in an extremely hot, dense state. We have a ton of evidence that the universe was once in such a state. Perhaps our understanding of this state will eventually lead to a theory of the origin of the universe, but the big bang theory as it stands does not claim to explain such an origin. — Matt O’Dowd, PBS Space Time
The "theory" of evolution is the same thing. We have no "proof" of it. But of course we do. Evidence is all around us, being evaluated in a multitude of ways by a multitude of people using different sources of data making similar conclusions supported by experiments and evidence. This is basically how we define "fact".
Of course somebody may stumble onto something that blows the whole equation up, but barring that, we have sufficient confidence to say it's fact. Granted the big bang theory is harder to observe, study, and experiment. Doesn't change how it's viewed by science.
(TFA opens with this. It suggests the possibility of something that may blow up the equation. Great. Similarly, if somebody can find something that disproves evolution that would be pretty ground-breaking, but the more established a fact, the higher the burden of proof.)
So this wasn't a model fitting the data. In fact it was an accidental observation which agreed with a model that had been suggested much earlier. The fact Penzias and Wilson weren't even looking for it makes it even more unbiased. Wilson, I believe, was also a solid state person (as were many prominent physicists in the 20s and 30s).
https://en.wikipedia.org/wiki/Georges_Lema%C3%AEtre
He "initially call[ed] it the 'hypothesis of the primeval atom'."