Did the universe Absolutely begin?

[JhonnyDx]

Did the universe Absolutely begin?

 

[phinds]

Did the universe Absolutely begin?

Your question is extemely vague. What does "absolutely begin" even mean?

In answer to what I THINK you are asking, the answer is we don't know

 

[JhonnyDx]

Absolutely begin, In the sense of undeniable, and very, very likely.

 

[phinds]

Absolutely begin, In the sense of undeniable, and very, very likely.

Then the answer remains, we don't know.

 

[JhonnyDx]

What is more likely?

 

[phinds]

What is more likely?

We don't know. It's turtles all the way down.

 

[Chalnoth]

There's no way to know at present what happened (if anything) before our region of space-time began.

One reason for this is that cosmic inflation, which is one of the prevailing models for the early universe, wipes out almost all information about what the universe was like prior to inflation. Without evidence, we can't say what happened before that (if anything).

 

[JhonnyDx]

The question is not knowing what was "before" (because time would also have begun), but if at some "moment" there was no universe.

 

[houlahound]

The universe we currently live in begins at every given moment.

 

[phinds]

The question is not knowing what was "before" (because time would also have begun), but if at some "moment" there was no universe.

And again, we don't know. I take it you are just not going to take that for an answer and you are going to continue to ask questions that end up at the same place. Seems like a waste of time, but good luck.

 

[Chronos]

If you are asking if a state unlike like that of the current universe preceded it, the answer is clearly yes. If you are asking if a state of absolute nothing preceded that of the currently known universe, that's more complicated. It starts with an argument in semantics [like how you define 'absolute nothing'?]. In the philosophical sense, absolute nothing never has and never will exist anywhere in the universe. That would imply a ponderable property enabling you to distinguish it from a pure state of nonexistence.

 

[PeterDonis]

if at some "moment" there was no universe.

What does this mean?

The fact that you keep on getting vague responses is because your questions are vague. I would advise taking a step back and thinking very carefully about what, exactly, you want to ask. It might help to ask yourself, what observations could we make (even if they're not at all practical, just possible in principle) that would tell us whether the answer to your question is yes or no? If you can't think of any, that's a red flag that your question is too vague.

 

[rootone]

If 'there is no Universe' then there is no anything.
Nothing happens.
Ever.

 

[lifeonmercury]

Scientists really need to get to the bottom of this. These questions are bugging a lot of people and it would help to have some answers.

 

[Drakkith]

Scientists really need to get to the bottom of this. These questions are bugging a lot of people and it would help to have some answers.

Hey, if you know a way to see past the CMB, invent brand new mathematical, philosophical, and scientific concepts that probably don't exist yet, and have the ability (and resources) to quickly develop the equipment necessary to carry out new observations to confirm these theories, please let scientists know.

If you don't, then just try to have a little patience. It's taken about 13 billion years to get to this point. It may take a few years more to find the answer.

 

[nikkkom]

Scientists _do_ think about it.

More precisely, they are trying to develop mathematically valid theories which explain how Big Bang started. Of course, there are also alternatives where time is infinite in the past direction too, not only in the future direction (for example, "eternal inflation" models), and thus in these models there is no beginning.

It's quite possible that several different fully consistent models will eventually be developed, but we won't be able to find any empirical means to distinguish them. Seeing 13bn years back into the past and past CMB "wall" is very hard.

 

[JhonnyDx]

The universe we currently live in begins at every given moment.

Is it starting every moment?

 

[JhonnyDx]

[quote = "phinds, pós: 5644881, membro: 310841"] E mais uma vez, nós não sabemos. Acho que você simplesmente não vão tomar isso como uma resposta e você vai continuar a fazer perguntas que acabam no mesmo lugar. Parece ser um desperdício de tempo, mas boa sorte. [/ QUOTE]

Thanks for your response. More sorry for my ignorance of wanting to hear what others have to say; Because you are the owner of the truth.

 

[JhonnyDx]

[QUOTE = "Chronos, post: 5644961, membro: 10970"] Se você está perguntando se um estado diferente de como a do atual universo precedeu, a resposta é claramente sim. Se você está perguntando se um estado de absoluta nada precedeu a do universo conhecido atualmente, isso é mais complicado. Ela começa com uma discussão na semântica [como como você define "nada absoluto"?]. No sentido filosófico, nada absoluto nunca foi e nunca vai existir em qualquer lugar do universo. Isso implicaria uma propriedade ponderável permitindo-lhe distingui-lo de um puro estado de inexistência. [/ QUOTE]

Was talking about the absence of space-time reality as a whole. Was the uniqueness eternal? Was it material?

 

[PeterDonis]

Was talking about the absence of space-time reality as a whole. Was the uniqueness eternal? Was it material?

Sorry, this doesn't make your question any less vague.

(Also, your quote of my post appears to be translated into Spanish.)

 

[JhonnyDx]

Excuse me. Plus I do not understand your placement. It's a simple question: did the universe have a beginning?

 

[PeterDonis]

It's a simple question: did the universe have a beginning?

The answer to this question is, we don't know. We have models in which it did, and models in which it didn't. We don't have enough evidence to distinguish between them.

 

[James Heimbach]

Your question isn't answerable by science or physics. Your question is a metaphysical one, one whose answer depends upon your worldview, your presuppositions. It is important for scientists to know when physics ends and metaphysics begins.

 

[phinds]

Your question isn't answerable by science or physics.

That is not known to be true. It MIGHT be true but it might not so it is just a personal theory.

 

[Drakkith]

That is not known to be true. It MIGHT be true but it might not so it is just a personal theory.

Let's not get used to using the term "personal theory" too loosely. His statement is by no means a personal theory.

 

[phinds]

Let's not get used to using the term "personal theory" too loosely. His statement is by no means a personal theory.

Well, personal opinion then. It's certainly not demonstrable fact (though I happen to agree w/ it).

 

[PeterDonis]

Your question isn't answerable by science or physics.

This statement is too strong. It is possible that we might eventually figure out a way to test the various proposed models and be able to rule out either all of the ones in which the universe has a beginning, or all the ones in which it doesn't. We don't know how to do that now, but that doesn't mean we never will.

If you were to say "Your question isn't currently answerable by science or physics", I would agree with that (in fact I already did earlier in this thread).

 

[rootone]

Your question isn't answerable by science or physics. Your question is a metaphysical one, one whose answer depends upon your worldview, your presuppositions. It is important for scientists to know when physics ends and metaphysics begins.

Physics ends when the ideas in discussion cannot be tested by observing and measuring stuff.

 

[windy miller]

Did the universe Absolutely begin?

i feel the responses to your question have been a little abrupt so Ill try and give you a fuller answer.
The observable universe is expanding and so if we wind the clock back its contracting.
There are theorems in general relativity ( our best theory of the large scale behaviour of the cosmos) called Penrose Hawking singularity theorems that imply that the space time somehow comes to an end in a finite amount of time about 13.8 billion years ago.
Some people interpret this as saying the universe had a beginning 13.8 bio years ago. But the problem here is that if these theories are right then the entire observable universe was once smaller than an atom. Under these conditions we need to take into account quantum mechanics ( our theory that describes the behaviour of sub atomic particles and more). The singularity theorems do not take account of quantum mechanics. So we need a a theory that combines quantum mechanics and general relativity. Alas we have no well verified theory that does this. We do have proposals that scientists take seriously like string theory and loop quantum gravity. People have used these theories to try and work out what happened at the big bang. A common prediction is that the big bang is replaced by a big bounce, so the universe was contracting before it was expanding. But these theories have not been verified by experiments, so these and other similar statements are speculative. Until we get a full theory of quantum gravity and have it verified by experiment we are not likely to know the answer to your question.
Even if we get the full theory we still might not know the answer to question. So I think a theory of quantum gravity is a necessary condition but it remains to be seen if it is sufficient condition. Since the necessary condition has not been fulfilled the answer to your question is right now: "we don't know". Anyone that claims to say with any high degree of confidence that the universe had a beginning or is eternal into the past in my opinion is over stepping that mark. I hope that provides you with a fuller answer to your question.

 

[Ghost117]

i feel the responses to your question have been a little abrupt so Ill try and give you a fuller answer.
The observable universe is expanding and so if we wind the clock back its contracting.
There are theorems in general relativity ( our best there of the large scale behaviour of the cosmos) called Penrose Hawking singularity theorems that imply that the space time somehow comes to an end in a finite amount of time about 13.8 billion years ago.
Some people interpret this as saying the universe had a beginning 13.8 bio years ago. But the problem here is that if these theories are right then the entire observable universe was once smaller than an atom. Under these conditions we need to take into account quantum mechanics ( our theory that describes the behaviour of sub atomic particles and more). The singularity theorems do not take account of quantum mechanics. So we need a a theory that combines quantum mechanics and general relativity. Alas we have no well verified theory that does this. We do have proposals that scientists take seriously like string theory and loop quantum gravity. People have used these theories to try and work out what happened at the big bang. A common prediction is that the big bang is replaced by a big bounce, so the universe was contracting before it was expanding. But these theories have not been verified by experiments, so these and other similar statements are speculative. Until we get a full theory of quantum gravity and have been it verified by experiment we are not likely to know the answer to your question.
Even if we get the full theory we still might not know the answer to question. So i think a theory of quantum gravity is a necessary condition but it remains to be seen if it is sufficient condition. Since the necessary condition has not been fulfilled the answer to your question is right now: "we don't know". Anyone that claims to say with any high degree of confidence that the universe had a beginning or is eternal into the past in my opinion is over stepping that mark. I hope that provides you with a fuller answer to your question.

Thank you for taking the time and care to summarize the relevant details, without actively trying to make the questioner feel stupid.

 

[weirdoguy]

But the problem here is that if these theories are right then the entire observable universe was once smaller than an atom.

That is not true.

 

[Fervent Freyja]

That is not true.

That statement is true.

 

[weirdoguy]

Ah, observable universe, I'm sorry. Yes, it's true then.

 

[vvolodin]

The question is not knowing what was "before" (because time would also have begun), but if at some "moment" there was no universe.

The universe we currently live in begins at every given moment.

What is moment?

 

[phinds]

What is moment?

moment = instant (in this case). That is, an indivisible unit of time

 

[houlahound]

No a moment is a precise unit of celestial time. There is a whole thread on it.

 

[phinds]

No a moment is a precise unit of celestial time. There is a whole thread on it.

Oh, I didn't realize it had a definition involving duration. I never think of it that way, but my usage is English, not Physics.

 

[phinds]

That statement is true.

Ah, observable universe, I'm sorry. Yes, it's true then.

Do either of you have a calculation to support this? The only calculation I've ever seen puts it at the size of a grain of sand, so very small but WAY bigger than an atom.

 

[houlahound]

The universe began when humans first observed it - I keed, I keed.

 

[andrewkirk]

It's a simple question: did the universe have a beginning?

It is anything but a simple question. I'll try to briefly explain why. There are two very vague words in the question: 'universe' and 'beginning'.

'Universe', in the context of a physics discussion, is usually taken to refer to this spacetime that we are in. So discussions of that universe beginning are about the earliest times in this spacetime manifold. But, based on its etymological roots, 'universe' means 'everything that exists'. So if there are many spacetimes (sometimes called a 'multiverse') then they are all part of the 'universe' too. Further, if there are other things that are nothing like spacetimes, they are also part of the universe under this definition (see Max Tegmark's 'Mathematical Universe' for an example of this idea taken to extremes). In fact, if there are deities or other beings that people think of as 'supernatural' then they too are part of the universe under that definition.

'Beginning' can also mean different things. For instance, what if time dimensions only exist as features of spacetimes, and there are multiple spacetimes? Then although we may be able to talk about a particular spacetime beginning, we cannot talk about a beginning of the set of all spacetimes, because there is no over-arching time dimension by reference to which we can make sense of the time-bound concept of 'beginning'.

Even when we focus on just one spacetime, the notion of beginning is a problem. We can define a universal coordinate system for the spacetime that has a time dimension, and we can identify a value of that coordinate such that no part of the spacetime has a time coordinate earlier than that. We can even adjust our scale so that that coordinate is time zero. We can then ask the question: is there any part of the spacetime that has that coordinate? Maybe there is, or maybe the times get closer and closer to zero but never reach it. If that is the case, would you count it as the universe having a beginning? Or would you only say the universe had a beginning if there is a part of the spacetime that has time coordinate zero?

Reflect deeply on what your question (which is actually about as far from a simple question as one can get) means, and you may get some insights as to the nature of the possible answers to it, or even whether an answer is even possible in theory (it may not be).

 

[russ_watters]

The answer to this question is, we don't know. We have models in which it did, and models in which it didn't. We don't have enough evidence to distinguish between them.

Maybe I'm just not sure of what "models" you speak, but would it be accurate to say the currently favored theory or collection of theories (BBT) implies a beginning?

 

[russ_watters]

I'm not sure if this was answered succinctly:

The question is not knowing what was "before" (because time would also have begun), but if at some "moment" there was no universe.

This question is - as far as we know - a self contradiction, since as you correctly point out "time" is a component of the universe and thus there can be no time (no "moment") - in the sense we know it - without it.

 

[houlahound]

If the universe means existence then there was no time existing before existence existed.

If the universe is the spacetime we inhabit then clearly it had a beginning according to all evidence.

 

[houlahound]

The CMB, Hubble shift, baryon Genesis, formation of galaxies etc all indicate this observed universe and its physics had a beginning.

Anything about any other universes I have no information on.

 

[PeterDonis]

would it be accurate to say the currently favored theory or collection of theories (BBT) implies a beginning?

I don't think so, because the current well-confirmed theory, the standard hot big bang model, does not go back further than the end of inflation (or what is assumed to be the end of inflation--the hot, dense, rapidly expanding state that is the earliest state for which we have both reasonable evidence and a well-accepted model). But the model explicitly recognizes that that state is not a "beginning"--something came before it. The open question is whether the something that came before it includes a genuine beginning or not. Some models do, as in the idealized FRW spacetime with no inflation (which has an initial singularity by the standard Hawking-Penrose singularity theorems), the original inflation model, or proposals like Hawking's "no boundary", i.e., a model in which there is a genuine finite "earliest time". Other models don't, as in eternal inflation models, bounce models, and probably others that I can't think of right now. I don't think we can say at this point which of those two types of models is going to win out; the pendulum seems to swing back and forth every few years or so and I don't see it settling yet. Others who are more knowledgeable about the latest research might be able to give better insight on that.

 

[nikkkom]

The CMB, Hubble shift, baryon Genesis, formation of galaxies etc all indicate this observed universe and its physics had a beginning.

No, it is not. These observed facts indicate that Universe was much denser, hotter, and more rapidly expanding 13.5 billion years ago.

They do not _prove_ that there was a "beginning" (i.e. that all timelike curves can only be traced back in time by a _finite_ amount). The "beginning" is merely a naive extrapolation of expansion back in time, which does not consider the very likely possibility that currently unknown physics appears at high densities and energies.

If you measure the strength and direction of Voyager 1 signals in many places across Solar system, the naive extrapolation of these observations is that there is an infinitely small, point source of radio signals approx. 137 AU from Sun; and since it's a point, it has an infinite power density, infinite EM field strength at the source, etc.

Of course, we all know that if you come really close to the Voyager 1, you'd see that the source of radio signals is not infinitely small. It's a completely normal object. No infinities.

 

[StandardsGuy]

Did the universe Absolutely begin?

Einstein's theories of relativity and the discovery that the universe appears to be expanding suggest that the universe started at a particular time (which was the beginning of time). However relativity breaks down at the "start" when the density would be infinite, so the beginning is not certain.

 

[PeterDonis]

Einstein's theories of relativity and the discovery that the universe appears to be expanding suggest that the universe started at a particular time (which was the beginning of time).

It would be more accurate to say that they suggested this when they were first discovered. Since then we have found plenty of possible models in which relativity holds and the universe is expanding now, but which do not have a beginning in the sense of a particular time at which the universe started.

However relativity breaks down at the "start" when the density would be infinite, so the beginning is not certain.

The reason we don't know whether there is a beginning is not necessarily tied to the fact that we expect GR to break down at sufficiently high densities. In some of the possible models, the density never approaches the Planck scale, so GR should be applicable, at least at the classical level, throughout the model.