An infinite universe?

[excreationist]

https://en.wikipedia.org/wiki/Big_Bang
says:

"These theories were based on the hypothesis that all the matter in the universe was created in one big bang at a particular time in the remote past"​

​Hoyle seems to be talking about very dense beginning rather than merely inflation......

Not sure how you got that but Hoyle was a fanatical believer in a steady state universe that always was and always will be just as we see it now.

I meant that Hoyle coined the term "Big Bang" when talking about theories where there was a big bang in the past where things apparently started with a dense point - rather than just using the term to just involve inflation....

I was under the impression that some physicists believe in both a singularity and then an infinite universe....

Indeed so and some that don't.

I'm curious about how they could explain an infinite universe coming from a finite size in a finite time.... does it require an infinite speed of expansion at some point?

 

[skepticalbip]

I meant that Hoyle coined the term "Big Bang" when talking about theories where there was a big bang in the past where things apparently started with a dense point - rather than just using the term to just involve inflation....

Hoyle used the term as a derision of the theory most people now call the Big Bang because he extrapolated back from the expansion model to a super dense universe and he thought the idea of a compact universe expanding out to what we now see to be so absurd that no one but an idiot could believe it.

I was under the impression that some physicists believe in both a singularity and then an infinite universe....

Indeed so and some that don't.

I'm curious about how they could explain an infinite universe coming from a finite size in a finite time.... does it require an infinite speed of expansion at some point?

That was why Guth proposed the inflationary phase to expand the universe from unimaginably dense to almost its current density almost instantaneously... so accounting for the smoothness of the universe.

 

[steve_bank]

Severa choices.

1. An finite universe that always was and will be, form changes over time.
2. A finite universe where if you go far enough you bounce of the end.
3. An finite number of possible derivations.
4. Invoke a god
5. Realize the question is unanswerable and don't take it too seriously.
6. If you have to have an answer, pick one that suits you,or make one up.

 

[excreationist]

Hoyle used the term as a derision of the theory we now call the Big Bang because he thought the idea of a compact universe to be so absurd that no one but an idiot could believe it.

Yes

I'm curious about how they could explain an infinite universe coming from a finite size in a finite time.... does it require an infinite speed of expansion at some point?

That was why Guth proposed the inflationary phase to expand the universe from unimaginably dense to almost its current density almost instantaneously.

In one of his videos he said something about "pocket universes".... does he believe our ordinary universe probably extends infinitely?

 

[excreationist]

Severa choices.

1. An finite universe that always was and will be, form changes over time.
2. A finite universe where if you go far enough you bounce of the end.
3. An finite number of possible derivations.
4. Invoke a god
5. Realize the question is unanswerable and don't take it too seriously.
6. If you have to have an answer, pick one that suits you,or make one up.

Or only the "observable universe" within the "cosmological horizon" we can observe exists in a simulation while the possibly infinite space outside of it might not exist....

 

[skepticalbip]

In one of his videos he said something about "pocket universes".... does he believe our ordinary universe probably extends infinitely?

I honestly don't know what Guth believes. He seems to be continually trying to patch the problems others are continually finding with his inflation idea.

 

[steve_bank]

Severa choices.

1. An finite universe that always was and will be, form changes over time.
2. A finite universe where if you go far enough you bounce of the end.
3. An finite number of possible derivations.
4. Invoke a god
5. Realize the question is unanswerable and don't take it too seriously.
6. If you have to have an answer, pick one that suits you,or make one up.

Or only the "observable universe" within the "cosmological horizon" we can observe exists in a simulation while the possibly infinite space outside of it might not exist....

My cosmology book used universe for that which is observable and detectable and Universe for all that exists whether we detect it or not.

Cosmology is mathematical speculation using known scintific models.

If you are looking for the meaning of life as Indiana Jones said to an Archeology class, philosophy is down the hall.

That there are different conclusions based on the BB should tell you there are no answers, at least not now.

Regardless of what reality 'is' for us humans we get up every day and do what we do. Whether you are a simulation or flesh and blood and can not knw the difference, the choices remain the same. That goes for theists and atheists as well.

 

[Jokodo]

Must be measurable in theory to be real.

It could be measured if there was something that could measure it.

Where's your limit theory? Beliefs aren't theories.
Infinity could be measured if there was something that could measure it.

An infinite length could be measured?

With an infinite yardstick and infinite time at hand, sure why not? Didn't you just say that if something "could be measured if there was something that could measure it", it becomes real?

How long would it take?

And combining limits with infinities is a way to deal with infinities in mathematics. Not in the real world.

 

[untermensche]

An infinite length could be measured?

With an infinite yardstick and infinite time at hand, sure why not? Didn't you just say that if something "could be measured if there was something that could measure it", it becomes real?

How long would it take?

And combining limits with infinities is a way to deal with infinities in mathematics. Not in the real world.

How much wood is needed for an infinite yardstick? Claiming a real infinity is an absurdity that creates the need for many infinities. Infinite space implies there was already infinite time to fill that space.

And how exactly is the final measurement achieved?

Infinite space is a line that moves forward without end.

No use of limits can deal with it. It can't be measured.

To be measured means you have a final measurement that can be taken. There is no finality in infinite space.

 

[steve_bank]

Back to yet another derail on infinity.

In practical applied math especially in engineering infinities and limits are common.

Infinity is not a number, it is a symbol or a reference for discussion. It is something that can be approached but never reached.

An equation expressed in complex variables for a single pole function is 1/(Sp + 1). In the limit as Sp-> -1 the function goes to infinity, we would say. In real physical systems it usually means some parameter will try to grow without limit until something breaks. A speed control system that under certain conditions will increase speed until something fails. It has happened in poorly designed control systems.

In cosmic terms for an infinite universe you can never get to an end that does not exist, it is not numerical. Not quite the same as mathematical treatment of infinities. In math and real world math models infinity can be asymptotically approached, but never reached.

That leads into poles and zeros, linear systems and complex variables. Dealing with infinities, or singularities, is actually routine.

 

[untermensche]

Back to yet another derail on infinity.

In practical applied math especially in engineering infinities and limits are common.

Infinitesimals are used to determine the area of finite spaces.

Infinities are not used.

An infinity can't be measured.

They don't exist.

 

[fromderinside]

Oh great. Now you are twisting what steve-bank meant and you know it. Most every interesting engineering problem deals with this or that indeterminably large (shorthand infinity) and infinitesimally small (limits) as a matter of class and of bounds.

IOW you've added nothing to the discussion.

Feeling good untermensche​?

 

[untermensche]

Oh great. Now you are twisting what steve-bank meant and you know it. Most every interesting engineering problem deals with this or that indeterminably large (shorthand infinity) and infinitesimally small (limits) as a matter of class and of bounds.

IOW you've added nothing to the discussion.

Feeling good untermensche​?

I feel great.

I have twisted nothing.

There is no magic to measure a line that is infinitely long.

It can't be done.

The imaginary infinitesimals of calculus are used to determine finite areas. They can't be used to measure an infinite line.

 

[skepticalbip]

Back to yet another derail on infinity.

Yup, looks like it. The problem this time, however, is in his decree that something must be measurable to be real. The proof of such a decree may be amusing if he would offer one.

 

[untermensche]

Back to yet another derail on infinity.

Yup, looks like it. The problem this time, however, is in his decree that something must be measurable to be real. The proof of such a decree may be amusing if he would offer one.

If it is real it is theoretically measurable. There is a way to measure it.

You cannot measure an infinite line.

 

[skepticalbip]

Back to yet another derail on infinity.

Yup, looks like it. The problem this time, however, is in his decree that something must be measurable to be real. The proof of such a decree may be amusing if he would offer one.

If it is real it is theoretically measurable. There is a way to measure it.

You cannot measure an infinite line.

You have declared that several times. And yet you have offered nothing to support the claim.

What is on the other side of the finite limit of space since you insist space is finite?

 

[untermensche]

If it is real it is theoretically measurable. There is a way to measure it.

You cannot measure an infinite line.

You have declared that several times. And yet you have offered nothing to support the claim.

What is on the other side of the finite limit of space since you insist space is finite?

It is definitional.

An infinite line is a line that has no end point.

Something with no end point cannot be measured. Not even in theory.

Saying space is finite is not claiming to know what is beyond boundaries that can't be approached.

 

[skepticalbip]

If it is real it is theoretically measurable. There is a way to measure it.

You cannot measure an infinite line.

You have declared that several times. And yet you have offered nothing to support the claim.

What is on the other side of the finite limit of space since you insist space is finite?

It is definitional.

An infinite line is a line that has no end point.

Something with no end point cannot be measured. Not even in theory.

Saying space is finite is not claiming to know what is beyond boundaries that can't be approached.

Can't you offer anything other than gibberish?

If space is finite that means it has an end. According to you it can then theoretically be measured. The question you didn't answer in your gibberish is what is on the other side of that end? More space? Then it isn't the end. If there is no end then it is infinite.

 

[bilby]

If it is real it is theoretically measurable. There is a way to measure it.

You cannot measure an infinite line.

You have declared that several times. And yet you have offered nothing to support the claim.

What is on the other side of the finite limit of space since you insist space is finite?

It is definitional.

An infinite line is a line that has no end point.

Something with no end point cannot be measured. Not even in theory.

Saying space is finite is not claiming to know what is beyond boundaries that can't be approached.

The equator is a line that has no end point.

That's not as significant a bar to either existence or measurement as you appear to think.

 

[steve_bank]

Back to yet another derail on infinity.

In practical applied math especially in engineering infinities and limits are common.

Infinitesimals are used to determine the area of finite spaces.

Infinities are not used.

An infinity can't be measured.

They don't exist.

I did not say an infite condition can exist.

So, by your thinking because an inity can not exist because it can't be expressed numerical y then an infinite universe can not exist?

We are talking about two different things. How asymptotes are handled in models which are reflected in actual physical reality, and an infinite universe. Math does not apply to the question of an infinite univers.
The question is philosophical. The debate can involve scince, but it is not answerable by any science or experiment.

Science must be testable in some way.