Big Bang not an instance of something from nothing?

[Alfred001]

Quote

There are actually no examples in the universe of anything being created "from nothing". The reason is that nowhere is there any "nothing" for "somethings" to be created from. Everywhere, there is "something"! (Even in the vacuum of deep space, between hydrogen atoms that are few and far between, there is something, i.e. space and the fundamental fields. Also the Big Bang is not "something from nothing", but that's another story.

I found the above quote on Quora, but I'm not registered there and I don't know how the damn thing works and it was an old post, so I'll ask here, what does the guy mean by the Big Bang not being something from nothing?

[Area54]

Disclaimer: I'm overly influenced by pop science explanations, but I'm confident others will correct any nonsense in my post.

We do not know what preceded the BB, but it entirely possible matter/energy were present in some form before the expansion of the current universe began. So,something coming from something else, not something from nothing.

Or, as the quote notes, "nothing" in physics is not quite the same as absolutely nothing. (There is an ongoing discusison about this somewhere on the forum,) We know that virtual particles can and do emerge from "nothing" then disappear. Some have suggested that the universe is just a large scale blip of virtual particles. Again, not something from nothing, but arguably something from "nothing".

Hope that clarified rather than confused.

[beecee]

As Area54 has said, is pretty well correct imo. What is important is our definition of "nothing". Is the quantum foam hypothetically from whence the BB arose nothing? In my opinion, pretty damn close! Are virtual particles nothing?

Here is a  hypothetical account of what is sometimes referred to as the Universe being the ultimate free lunch, or a universe from nothing.

https://www.astrosociety.org/publications/a-universe-from-nothing/

[Strange]

Also, although there is a concept of "time = zero" in a naive extrapolation of the expansion we observe this doesn't really mean anything. Our theories of how things behave break down before you get to that point. So the model currently says nothing about the creation of the universe (from nothing or from something). 

In other words, not only can we not say anything about before the Big Bang we can't even say anything about "at" the Big Bang. 

So the Big Bang model is about the (current) expansion of the universe from an early hot, dense state  

We probably need a theory that combines gravity and quantum theory before we can say more about the early universe. Af least one attempt to do this suggests that the universe is infinitely old. 

[Airbrush]

Nothing never existed, nor will it ever exist, and that is infinitely old.

Edited July 27, 2017 by Airbrush

[Strange]

4 minutes ago, Airbrush said:

Nothing never existed, nor will it ever exist, and that is infinitely old.

Evidence?

[Airbrush]

20 hours ago, Strange said:

Evidence?

Are there any theories in cosmology about "nothing"?  What exactly is nothing?

[Strange]

9 minutes ago, Airbrush said:

Are there any theories in cosmology about "nothing"?  What exactly is nothing?

See the link in beecee's post above: 

On 26/07/2017 at 9:24 PM, beecee said:

As Area54 has said, is pretty well correct imo. What is important is our definition of "nothing". Is the quantum foam hypothetically from whence the BB arose nothing? In my opinion, pretty damn close! Are virtual particles nothing?

Here is a  hypothetical account of what is sometimes referred to as the Universe being the ultimate free lunch, or a universe from nothing.

https://www.astrosociety.org/publications/a-universe-from-nothing/

 

[Thorham]

26 minutes ago, Airbrush said:

Are there any theories in cosmology about "nothing"?  What exactly is nothing?

Yes. It's something. Like we say a glass is empty while there is still air inside.

[Airbrush]

"... the universe is the ultimate free lunch!  It came from nothing, and its total energy is zero, but it nevertheless has incredible structure and complexity. There could even be many other such universes, spatially distinct from ours."

Excellent article and not too difficult for me.

What about the incredible structure and complexity of the universe?  That is not nothing.  The universe did not come from nothing, it came from zero energy, some kind of potential condition from which a universe can appear.

 

 

 

 

[Nader]

Is it my incorrect understanding or does the inflation theory suggest expansion of the universe far faster than our current speed limit of light? if so how do we justify this theory?

Edited July 29, 2017 by Nader

[beecee]

31 minutes ago, Nader said:

Is it my incorrect understanding or does the inflation theory suggest expansion of the universe far faster than our current speed limit of light? if so how do we justify this theory?

In the simplest interpretation, the universe is expanding FTL and inflation did also...spacetime does not have mass and therefor is not inhibited by any speed limit.

In more professional terms though, we must be clear on what we mean by the universe expanding FTL....Sean Carroll explains far better then anything I could........

http://www.preposterousuniverse.com/blog/2015/10/13/the-universe-never-expands-faster-than-the-speed-of-light/

 

extract:

"1.The expansion of the universe doesn’t have a “speed.” Really the discussion should begin and end right there. Comparing the expansion rate of the universe to the speed of light is like comparing the height of a building to your weight. You’re not doing good scientific explanation; you’ve had too much to drink and should just go home.The expansion of the universe is quantified by the Hubble constant, which is typically quoted in crazy units of kilometers per second per megaparsec. That’s (distance divided by time) divided by distance, or simply 1/time. Speed, meanwhile, is measured in distance/time. Not the same units! Comparing the two concepts is crazy.

Admittedly, you can construct a quantity with units of velocity from the Hubble constant, using Hubble’s law, v = Hd (the apparent velocity of a galaxy is given by the Hubble constant times its distance). Individual galaxies are indeed associated with recession velocities. But different galaxies, manifestly, have different velocities. The idea of even talking about “the expansion velocity of the universe” is bizarre and never should have been entertained in the first place".

 

more at the link......

[StringJunky]

38 minutes ago, Nader said:

Is it my incorrect understanding or does the inflation theory suggest expansion of the universe far faster than our current speed limit of light? if so how do we justify this theory?

Space, being only volume, can expand at any rate without violating the SOL limit. If the universe is infinite then it was always so.

[Area54]

7 hours ago, StringJunky said:

Space, being only volume, can expand at any rate without violating the SOL limit. If the universe is infinite then it was always so.

Has it been established that the finite cannot become infinite? Since I am unable to conceive of either concept without melting my brain I cannot tell how dumb a question that was.

[Strange]

2 minutes ago, Area54 said:

Has it been established that the finite cannot become infinite? Since I am unable to conceive of either concept without melting my brain I cannot tell how dumb a question that was.

Not that I am aware of. There are mathematical functions that (if treated as a rate of growth) would go from a finite to an infinite value in finite time. So if the creation of matter from "nothing" followed such a function, it could become infinite. 

On the other hand, there are no models based on this, as far as I know. Most people would say that if the universe is infinite now then it must have always been infinite.

[Area54]

Thank you. It was a question I had never seen asked before and I was curious whether the possibility was automatically exlcuded in some way.

[StringJunky]

1 minute ago, Area54 said:

Thank you. It was a question I had never seen asked before and I was curious whether the possibility was automatically exlcuded in some way.

i added that second sentence as a caveat in case my response lead to that because it might invoke thoughts of infinite rates. I wasn't aware that it was possible mathematically until Strange just mentioned it. 

[Strange]

19 hours ago, Nader said:

Is it my incorrect understanding or does the inflation theory suggest expansion of the universe far faster than our current speed limit of light? if so how do we justify this theory?

The "speed limit" only applies locally to objects moving past each other. It is not relevant to distances increasing because of the expansion of space. The speed of expansion is proportional to distance. So (even without inflation) there are points which are sufficiently far apart that they are moving apart faster than the speed of light.

Also, the speed of light being a limit on relative motion and the expansion of space both come from the same theory so, by definition, they cannot be contradictory (as the theory is mathematically consistent). What this means is that you cannot apply results from the simplified theory (special relativity) to cosmology (which requires the more general theory).

[Airbrush]

The idea of something finite in size growing to an infinite size is hard to imagine.   That means an infinite growth rate.  I doubt it until I hear an argument in favor of it.

[Alfred001]

On 7/26/2017 at 10:01 PM, Area54 said:

We know that virtual particles can and do emerge from "nothing" then disappear.

Is this true?

So IS there anything in the Universe that comes from nothing?

[beecee]

1 hour ago, Alfred001 said:

Is this true?

So IS there anything in the Universe that comes from nothing?

Scientifically speaking, a Universe from nothing is actually the only definitive answer: Unless something like the quantum foam [which some may see as nothing anyway] has always existed.

 https://www.youtube.com/watch?v=-EilZ4VY5Vs

 

[Carrock]

22 hours ago, Airbrush said:

The idea of something finite in size growing to an infinite size is hard to imagine.   That means an infinite growth rate.  I doubt it until I hear an argument in favor of it.

Many theories predict something critical becoming infinite (or zero) in certain situations e.g. inside a black hole. This is usually described as a singularity.

The definition of singularity is a bit vague, but it generally means that the theory is useless in that situation, and unknown physics or a new theory is required.

[Area54]

On 29/07/2017 at 10:28 PM, Airbrush said:

The idea of something finite in size growing to an infinite size is hard to imagine.   That means an infinite growth rate.  I doubt it until I hear an argument in favor of it.

Isn't that an argument from personal incredulity?

[Airbrush]

13 hours ago, Area54 said:

Isn't that an argument from personal incredulity?

Then try your best to explain how a finite size can grow to an infinite size.   I am eager to learn.

As for what exactly is "nothing", is it simply the absence of all matter or energy?

 

Edited July 31, 2017 by Airbrush

[Strange]

32 minutes ago, Airbrush said:

Then try your best to explain how a finite size can grow to an infinite size.   I am eager to learn.

Say the universe grew according to the tan function, for example. That goes to infinity in finite time. 

There is no cosmology based on this idea, but you can't just say it is impossible.