# Is the Universe infinite?

## 106 posts in this topic

On 22.8.2017 at 3:24 AM, Strange said:

So an observer half way to the edge of our observable universe would have their own observable universe, and they would see it as having the same age as ours. As far as we know, that will be true wherever you are in the universe.

Quote

The Observable Universe is clear.

However,

1. Infinite Universe vs Observable Universe

A. Assuming that we could move 1 Trillion Light year away from Earth at any direction (Deep into the Infinite Universe):

Should we see a similar space view as we see from our current location?

B. Is there any characteristics change between the two? (CRM, Temp...)

C.  Can we assume that the Observble Universe is covered by the Infinite Universe?

D. Is there any edge to the infinite Universe?

2. Temp - If the temp of the Infinite Universe is identical to the Obseravble Universe:

A. Can we see it as an example of small oven inside a Huge oven (both at the same temp)?

If So, by opening the door of the inside oven, Can we decrease its temp?

B. In the same token. How could the Observable Universe decrease its temp if it is covered by an infinite Universe with the same temp?

0

##### Share on other sites
19 minutes ago, Dan B. said:

The Observable Universe is clear.

However,

1. Infinite Universe vs Observable Universe

A. Assuming that we could move 1 Trillion Light year away from Earth at any direction (Deep into the Infinite Universe):          Should we see a similar space view as we see from our current location?

That is the assumption but, of course, we can't know. There is no reason to think it would be significantly different but maybe things change very gradually as you move through the universe (gradually, because the observable universe appears completely homogeneous & isotropic).

Quote

B. Is there any characteristics change between the two? (CRM, Temp...)

We don't know but assume not.

Quote

C.  Can we assume that the Observble Universe is covered by the Infinite Universe?

Sorry, don't know what that means.

Quote

D. Is there any edge to the infinite Universe?

No, because it is infinite. (Actually, in current models even a finite universe has no edge.)

Quote

2. Temp - If the temp of the Infinite Universe is identical to the Obseravble Universe:

A. Can we see it as an example of small oven inside a Huge oven (both at the same temp)?       If So, by opening the door of the inside oven, Can we decrease its temp?

The trouble with an oven as an analogy is that it implies a source of heat. Also, if they were both at the same temperature then opening the door wouldn't have any effect.

Quote

B. In the same token. How could the Observable Universe decrease its temp if it is covered by an infinite Universe with the same temp?

They are both decreasing in temperature in the same way. This is basically the ideal gas law which relates temperature to volume and pressure. As the universe expands it naturally cools (think of an aerosol can, when you release the gas it gets cold - or the opposite when you squeeze a bicycle pump).

0

##### Share on other sites
2 hours ago, Strange said:
Quote

B. In the same token. How could the Observable Universe decrease its temp if it is covered by an infinite Universe with the same temp?

They are both decreasing in temperature in the same way. This is basically the ideal gas law which relates temperature to volume and pressure. As the universe expands it naturally cools (think of an aerosol can, when you release the gas it gets cold - or the opposite when you squeeze a bicycle pump).

1. Aerosol can - Yes, I fully agree that when you release gas it gets cold. However, in order to set it we need to have two different segments of pressure. If the pressure in the can equivalent to the presure outside the can, there will be no gas flow and no gas gets cold.

2. It seems to me that we do not know how Infinity Universe really works. We might get a severe error by implementing an intuitive finite knowledge on the Infinity.

3. Thermodynamics - Do we have a chapter in thermodynamics which covers the infinity? If not, than it's the time to write it.

0

##### Share on other sites
1 hour ago, Dan B. said:

1. Aerosol can - Yes, I fully agree that when you release gas it gets cold. However, in order to set it we need to have two different segments of pressure. If the pressure in the can equivalent to the presure outside the can, there will be no gas flow and no gas gets cold.

Like all analogies, that has limited applicability. It only shows how temperature os related to volume and pressure.

The universe is expanding but not into anything so the analogy doesn't apply in that sense.

Quote

2. It seems to me that we do not know how Infinity Universe really works. We might get a severe error by implementing an intuitive finite knowledge on the Infinity.

You will certainly get confused if you apply intuitive knowledge of infinity. Scientists do not do that.

Quote

3. Thermodynamics - Do we have a chapter in thermodynamics which covers the infinity? If not, than it's the time to write it.

Is there anything that says it is limited to finite situations?

But as you have gone from asking questions to rejecting science, you probably won't get any more answers from me.

0

##### Share on other sites
7 hours ago, Dan B. said:

However,

1. Infinite Universe vs Observable Universe

The observable universe is simply that part of the universe that EMR from distant regions has had time to reach us: If the universe is infinite, then by definition it stretches far beyond anything we can or will ever be able to measure.

Quote

A. Assuming that we could move 1 Trillion Light year away from Earth at any direction (Deep into the Infinite Universe):

Should we see a similar space view as we see from our current location?

B. Is there any characteristics change between the two? (CRM, Temp...)

The evidence so far tells us that the universe/spacetime is isotropic and homogeneous, at least for the observable universe and we (scientists that is) have no reason to believe that would not extend everywhere. The CMBR would be the same over there as it is here.

Quote

C.  Can we assume that the Observble Universe is covered by the Infinite Universe?

D. Is there any edge to the infinite Universe?

Logically the universe as a whole, extends beyond our observable horizon in all directions, and probably to infinite quantities. There are no edges or centers to any reasonable current model of the universe/spacetime, either finite or infinite.

Quote

2. Temp - If the temp of the Infinite Universe is identical to the Obseravble Universe:

Our assumptions on the isotropic and homogeneous nature of the universe tells us that they should be the same.

Quote

A. Can we see it as an example of small oven inside a Huge oven (both at the same temp)?

If So, by opening the door of the inside oven, Can we decrease its temp?

B. In the same token. How could the Observable Universe decrease its temp if it is covered by an infinite Universe with the same temp?

Analogies while certainly being useful, all have limitations. Your second question is simply physics and as Strange has said, is just the relationship between volume, pressure and temperatures and is evidenced in many ways in our general day to day living..

Quote

2. It seems to me that we do not know how Infinity Universe really works. We might get a severe error by implementing an intuitive finite knowledge on the Infinity

I must admit my understanding of infinite and infinite quantities is lacking somewhat and I was advised back in the thread to read up on this topic which I intend to do. In the meantime my limited research so far tells me that infinity exist when relevant quantities are stretched far beyond what we will ever be capable of measuring and/or knowing: I am certainly more comfortable with that definition so far. Remember even when cosmologists speak of a physical BH singularity, or the BB singularity, they are not automatically inferring infinite quantities, although such singularities may lead to infinite quantities.

I welcome any comment from any reputable source as to the validity or otherwise of what I have posted above...any errors, alterations and/or corrections?

Edited by beecee
0

##### Share on other sites

Interesting discussipn so far.

I would like to note in regards to thermodynamics and the oven mentioned above.

Under the classical ideal gas laws treat all thermodynamics as a homogeneous and isotropic fluid with adiabatic ( no inflow or outflow of energy) expansion.

Now think about the observable universe and lets assume the above isn't true but instead we have a surrounding universe that isn't of the same temperature as the observable portion state.

As you approach the further regions of our observable universe the temperature will have a gradiant, depending on the temp variation.

So no longer homogeneous and isotropic...

Our observations agree strongly that this isn't the case and the immediate regions (regions of shared causality overlap) outside our observable portion will be roughly the same thermodynamic state.  Beyond regions of possible shared causality overlaps we simply will never know.

Edited by Mordred
0