Do Aliens actually exist ?

[BlueMoonAcrossThePond]

It's not very likely that space is infinite, BTW. It's a possibility, that is all. The reality is we have no idea.

It is in fact likely that space is infinite. We do in fact have good reason to believe so.

It is however, possible that space curves in upon itself at a very, very, very small rate of curvature.

It's also possible that space somehow behaves entirely out-of-norm at some point and comes to a hard edge.

We have attempted to measure the curvature of space with a great deal of accuracy - so far, all measurements indicate that the universe is infinite.
===
On the other hand, it's true that some fat guy somewhere is responsible for the recent hacks into sensitive USA government websites; and not the Russians.

It's possible that climate change isn't real.

It's possible that evolution is wrong and that intelligent design is true.

Each of the above claims is extremely unlikely to be true however based on facts on hand. So too is the claim that we have no idea about whether or not space is finite (albeit to a lesser extent).

 

[Chippy_boy]

The final alternate is that the universe is flat but somehow comes up against a hard edge - is possible. But it's entire against anything we've observed and is rejected as likely by cosmologists.

Sorry that is just not correct. A flat universe - if indeed it is flat - can be either finite or infinite. It does not need a hard edge in order to be finite, and I agree that is a ludicrous idea.

Or it could be finite now, but continually expanding so that it becomes infinite at T=infinity. We simply do not know and there is no consensus view amongst top scientists. Or at least if there is, then I am all ears.

EDIT: I see you added more. What you added is still wrong (sorry). All measurements DO NOT show that the universe is infinite. They merely show that we have failed to detect that it is finite. The two things are completely different.

 

[metalblue]

Sorry that is just not correct. A flat universe - if indeed it is flat - can be either finite or infinite. It does not need a hard edge in order to be finite, and I agree that is a ludicrous idea.

Or it could be finite now, but continually expanding so that it becomes infinite at T=infinity. We simply do not know and there is no consensus view amongst top scientists. Or at least if there is, then I am all ears.

EDIT: I see you added more. What you added is still wrong (sorry). All measurements DO NOT show that the universe is infinite. They merely show that we have failed to detect that it is finite. The two things are completely different.

It’s a restaurant isn’t it?

 

[BlueMoonAcrossThePond]

Sorry that is just not correct. A flat universe - if indeed it is flat - can be either finite or infinite. It does not need a hard edge in order to be finite, and I agree that is a ludicrous idea.

Or it could be finite now, but continually expanding so that it becomes infinite at T=infinity. We simply do not know and there is no consensus view amongst top scientists. Or at least if there is, then I am all ears.

EDIT: I see you added more. What you added is still wrong (sorry). All measurements DO NOT show that the universe is infinite. They merely show that we have failed to detect that it is finite. The two things are completely different.

Agree that the outcome - infinite versus not - is undecided.

I did not claim that measurements showing lack of curvature prove that the universe is flat - you've misinterpreted my statements. I do claim that if the universe does curve in upon itself, it is extremely gradual and is beyond our capability to measure.

It seems to me that a finite but infinitely expanding universe must entail a hard edge. This idea does seem to be open among cosmologists though.

 

[BlueMoonAcrossThePond]

There is no evidence the universe is flat indeed current thought is that it has a probability of 99% of being curved

>> There is no evidence the universe is flat
Huh?

>> Indeed current thought is that it has a probability of 99% of being curved
Based on what? Source?

 

[Chippy_boy]

Agree that the outcome - infinite versus not - is undecided.

I did not claim that measurements showing lack of curvature prove that the universe is flat - you've misinterpreted my statements. I do claim that if the universe does curve in upon itself, it is extremely gradual and is beyond our capability to measure.

It seems to me that a finite but infinitely expanding universe must entail a hard edge. This idea does seem to be open among cosmologists though.

I'm glad you now agree that it is undecided, but further, there is no consensus that an infinite universe is the more likely scenario. As I say, we simply do not know.

Once again however, a finite curved universe does *not* imply an edge. Spacetime itself is curved and therefore - in the finite universe scenario - there is no greater volume for the universe to expand *into*. The finite curved universe *is* the entirety of everything. You need to get away from this idea of a sphere suspended *in* some larger space - it's a flawed concept.

 

[BlueMoonAcrossThePond]

I'm glad you now agree that it is undecided, but further, there is no consensus that an infinite universe is the more likely scenario. As I say, we simply do not know.

Once again however, a finite curved universe does *not* imply an edge. Spacetime itself is curved and therefore - in the finite universe scenario - there is no greater volume for the universe to expand *into*. The finite curved universe *is* the entirety of everything. You need to get away from this idea of a sphere suspended *in* some larger space - it's a flawed concept.

>> Once again however, a finite curved universe does *not* imply an edge.
Obviously a curved universe does not need to have an edge.

My statement once more is this (flat added for further clarification):
It seems to me that a finite but infinitely expanding *flat* universe must entail a hard edge. If the universe is curved but expanding, obviously this isn't so. See above.

To reiterate - there's no evidence that the universe is curved - indeed, in spite of our best measurements, the universe appears to be flat. That's not to say, however, that the universe is flat - indeed the curvature of the universe should it exist may simply be beyond our capability to measure, and that in fact, the universe is curved, possibly finite, possibly infinite.

The finite versus infinite universe conundrum may unfortunately reside in Pauli's category of questions whose answer is "not even wrong."

 

[Chippy_boy]

>> Once again however, a finite curved universe does *not* imply an edge.
Obviously a curved universe does not need to have an edge.

My statement once more is this (flat added for further clarification):
It seems to me that a finite but infinitely expanding *flat* universe must entail a hard edge. If the universe is curved but expanding, obviously this isn't so. See above.

To reiterate - there's no evidence that the universe is curved - indeed, in spite of our best measurements, the universe appears to be flat. That's not to say, however, that the curvature of the universe is beyond our capability to measure, and that in fact, the universe is curved, possibly finite, possibly infinite, but beyond our ability to measure.

It is not clear to me whether you understand what a flat universe means. All it means is that it obeys Euclidian geometry, i.e. triangles add up to 180 degrees, parallel lines never meet etc. A universe which obeys these properties is said to be flat - in that a 2D representation of such a universe could be laid on a flat piece of paper.

The question then is, is such a flat piece of paper infinite or finite? Whether the universe is flat or not, has no bearing on whether it may be infinite or not. The piece of paper could be donut shaped and finite but still flat, still obeying Euclidian geometry. Or it could be infinite.

Anyway, enough of this. I stepped in merely to pick you up on your "it is very likely that the universe is infinite" line.

 

[BlueMoonAcrossThePond]

It is not clear to me whether you understand what a flat universe means. All it means is that it obeys Euclidian geometry, i.e. triangles add up to 180 degrees, parallel lines never meet etc. A universe which obeys these properties is said to be flat - in that a 2D representation of such a universe could be laid on a flat piece of paper.

The question then is, is such a flat piece of paper infinite or finite? Whether the universe is flat or not, has no bearing on whether it may be infinite or not. The piece of paper could be donut shaped and finite but still flat, still obeying Euclidian geometry. Or it could be infinite.

Anyway, enough of this. I stepped in merely to pick you up on your "it is very likely that the universe is infinite" line.

Touche.

 

[Chippy_boy]

Touche.

I have no idea why you said Touche. Maybe you do understand and are just careless with your words. Bye for now.