# Is spacetime a container?

1. Nov 12, 2015

### David Brill

Does it make sense to think of our universe as a "container" of matter and energy? If so, is there some minimal content?

Last edited: Nov 12, 2015
2. Nov 12, 2015

### Staff: Mentor

It's hard to say until we have a clear definition of "container" (general principle: any time you find yourself using scare-quotes in a question, the question still isn't precise enough to have an answer).

Clearly the universe contains matter and energy, so maybe the answer is "yes". But you already knew that, so I don't think that's what you mean.

3. Nov 12, 2015

### Smattering

Hm ... a container usually can exist independently of its content, but I remember some quote from Einstein where he questioned that space time can exist independently from matter and energy.

4. Nov 12, 2015

### phinds

I always think of it as just a metric. Things have varying distances from each other and the measure of those distance is the metric of space. They change distances from each other and that is one way to formulate a metric of time. "Container" is just too loaded a word, as others have already pointed out.

5. Nov 12, 2015

### Chronos

Given the usual definition of the universe is all of existence, space and its contents are all a part of that same reality, so it makes little sense to assign a separate identity to either entity.

6. Nov 12, 2015

### rootone

I would usually think of a container as being a material object which encloses other material objects.
(Well I guess it doesn't need to be strictly material, since there are things like magnetic confinement.)
However, there are by definition no objects or fields outside of the Universe, so therefore the contents of the universe cannot be said to be enclosed (or contained) by any such external object (or field).

Last edited: Nov 12, 2015
7. Nov 12, 2015

### David Brill

I guess I shouldn’t have used the word “container”. Basically, I was just wondering if the universe could be empty. That is, could space-time exist without having anything in it?

After reading your replies, I get the impression that that’s not possible. One comment above says that Einstein questioned whether space-time could exist independently of matter and energy. Additionally, I couldn’t find much online except for a theory, the Milne Model, that has apparently been discredited.