Nothing, something and the Universe

[kolo12]

Hello!
It is my first question on this site!
So I have some problems:
1. Is it possible to get something from absolute nothing?
2. I saw theory about universe from "nothing" but was it really absolute nothing? Is that possible? I know about quantum fluctuations and virtual particles but it is "nothing"? Or there is another theory with universe from absolute nothing?
3. What is physics definition of "nothing"?

Thanks!

 

[Voltageisntreal]

1. No - energy cannot be created or destroyed.
2.Since the answer to 1 is no, the answer to number 2 is no.
3.It's relative to something, i.e. the absense of something. So it would have to be the absense of space and time, the absense of existence itself.

As far as we know, we live in a universe of causality. Something causes something else. That brings us to the issue what caused the universe? Well it'd have to be from a universe which is not based on causality?

Consider that there is no guarantee that tommorow physics as we know it could not all change completey. What stops it from doing so? Existence is based on consistent laws, it's just how our universe and existence works. Beyond that we simply do not know.

But as far as we DO know- energy is conversed.

 

[kimbyd]

But as far as we DO know- energy is conversed.

This isn't correct at all. Energy isn't conserved in General Relativity.

This is a good blog post that describes it well, I think:
http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/

Hello!
It is my first question on this site!
So I have some problems:
1. Is it possible to get something from absolute nothing?
2. I saw theory about universe from "nothing" but was it really absolute nothing? Is that possible? I know about quantum fluctuations and virtual particles but it is "nothing"? Or there is another theory with universe from absolute nothing?
3. What is physics definition of "nothing"?

In reverse order:
3. There is no physical definition of nothing. Nothing is a colloquial term, and there's just no good way to define it precisely. Sometimes theoretical physicists use the term, but it usually ends up being just sloppy and misleading.
2. I think what people are usually referring to in this instance is a universe stemming from a previous vacuum state. This is certainly plausible, given the right conditions: a quantum vacuum doesn't have to be a static system. There can be fluctuations, and it may be possible for some tiny fraction of those fluctuations to create a new universe (by starting inflation). The new universe would be isolated from the parent universe: it would look like a microscopic black hole that suddenly appeared then evaporated just as quickly. But from the inside, it could be just as big and diverse as our own universe. At present, however, this is little more than an idea. We don't have a solid enough grasp of how quantum mechanics interacts with gravity to say whether or not this kind of thing is possible.
1. It's not clear. If you don't have a solid definition of nothing, how can you describe how nothing can transition into something? My suspicion is that this way of looking at things probably just doesn't make sense because true nothing also wouldn't have either space or time, which would mean that there's no way of describing it as changing (things can't change without time).

 

[stoomart]

Hello!
It is my first question on this site!
So I have some problems:
1. Is it possible to get something from absolute nothing?

No, that would be creationism, which is a philosophical topic and not something science can be used to explain.

2. I saw theory about universe from "nothing" but was it really absolute nothing? Is that possible? I know about quantum fluctuations and virtual particles but it is "nothing"? Or there is another theory with universe from absolute nothing?

No, something can't come from nothing, see above.

3. What is physics definition of "nothing"?

I'm not a physicist, but logic would say nothing is the absence of something.

 

[stoomart]

1. It's not clear. If you don't have a solid definition of nothing, how can you describe how nothing can transition into something? My suspicion is that this way of looking at things probably just doesn't make sense because true nothing also wouldn't have either space or time, which would mean that there's no way of describing it as changing (things can't change without time).

Agreed. I would define 'something' as a thing (having physical (what), location (where), and time (when) properties) in relation to some other thing; 'nothing' would be void of these properties and is null.

 

[PeterDonis]

Is it possible to get something from absolute nothing?

These terms are too vague for the question to have a meaningful answer.

I saw theory about universe from "nothing"

"I saw theory" is not a valid reference. In future, please give a specific reference. And it should be to a valid source, which almost always means a textbook or peer-reviewed paper; pop science articles (one of which I strongly suspect to be where you read this "theory") are not acceptable.

What is physics definition of "nothing"?

There isn't one; "nothing" is not a physics term. At best it's a pop science term, used in articles which are more concerned with attracting readers than in giving accurate explanations.

This thread is based on questions which are too vague to have meaningful answers. Accordingly, the thread is closed.