Where Did It All Come From?

[pantheory]

On 2/28/2024 at 9:52 PM, pantheory said:

 

Hi Weez,

 

The answer to your question depends on the theory that you might believe is correct. The original Big Bang theory traced the beginning of the universe to a beginning entity which they called a "Singularity." Although this is no longer part of most versions of mainstream theory, there are some very logical aspects to this original BB theory IMO.

 

According to the original version there was no such thing as time and space before the beginning entity, since the word "before" has no meaning in this context. It was simply time zero before any changes to this entity occurred. Time can be equated with change, so the first change in this entity was the beginning of time, and the first change in the volume that it occupied was the beginning of space, a vacuous volume within this entity.......................................

 

 

 

What I wrote above relates the original Big Bang theory. It is not my own theory, although it relates more to my theory than present BB theory. If valid it could explain the answer to the question "where did it all come from," the answer being a beginning entity.

 

Since then many promote the idea of time before the Big Bang. If there was a time or anything else before the beginning entity, then where did that come from? there is no mainstream answer to that question. Einstein believed in a forth physical dimension where space curves around on itself, so if one goes in a straight line you will eventually end up back to where you started from. But this idea is also changing since most all observations seem to point to what is called a flat universe, meaning that it is either bounded, or it has no end to it. No end to it is a type of continuum in the language of physics. But what would be the meaning of space without anything at all in it.

 

As for me, I prefer "simple" answers. Space is the distance between matter, beyond matter and field there would be no meaning to the word space, And if no changes ever occurred there would be no meaning to the word time. So both time and space can be simply defined, Of course more complicated definitions can easily be found. Without substance there could be no meaning to either time or space, If there was anything before a beginning entity, time, space, a field etc. then where did that come from? The simplest answer is that nothing came before that if one likes simplicity, then Occam's Razor is a good principle to consider.

 

https://www.britannica.com/topic/Occams-razor

[walterpthefirst]

7 hours ago, Weezer said:

I am still with you Walter, so keep on going. 

 

Thanks Weezer.

 

 

Today looks kinda busy for me so if I can make some time to carry on here I'll do so.

 

If not, it'll have to be as soon as I can manage.

 

Sorry 'bout that.

 

 

Walter.

[walterpthefirst]

As for me, I prefer "simple" answers. Space is the distance between matter, beyond matter and field there would be no meaning to the word space, And if no changes ever occurred there would be no meaning to the word time. So both time and space can be simply defined, Of course more complicated definitions can easily be found. Without substance there could be no meaning to either time or space, If there was anything before a beginning entity, time, space, a field etc. then where did that come from? The simplest answer is that nothing came before that if one likes simplicity, then Occam's Razor is a good principle to consider.

 

https://www.britannica.com/topic/Occams-razor

 

 

Pantheory, could you please give a reason why reality should bend to your personal preference?

 

 

 

Walter.

[walterpthefirst]

It look like I might have a chance to carry on today after all, Weezer.   So here goes.

 

 

To better understand why this Singularity isn't a point from which the universe explodes we need to look at two items of science history.  They will tell us why so many people are stuck on this idea of the Big Bang as a kind of explosion that radiates energy outwards.  So lets try and understand those two things.  I'll try and tackle the first of them today.

 

The first one has to do with Albert Einstein's work on General Relativity (GR) in the early years of the 20th century.  Back then nobody knew what I referred to yesterday, in my first explanation - that the Milky Way was just one of many galaxies and the others all seemed to be moving away from us.  Nobody knew that.  Not even Einstein.  So, the prevailing model of the universe at that time was a static and finite one.  There were no galaxies and nothing was moving away from us.  A finite volume of space was filled with stars, which were born and then died, with new stars replacing them and with this process going on forever and ever.  No beginning and no end, but a fixed and finite volume of space, probably with an edge or boundary.

 

So when Einstein was working on GR he found that his calculations didn't match up with those expectations.  Instead of his math predicting a nice, stable universe of stars it predicted a dynamic universe where everything moved away from everything else.  (Sound familiar?)  It turns out that he had predicted the receding motion of the galaxies before astronomers discovered them and found that this was exactly what they were doing - receding from us.  

 

Now then Weezer, what happens if you expect the universe to be of a limited size and your math tells you that everything in it is moving away from everything else?

 

Exactly!  Such a spherical universe with a boundary must have a fixed centre. All the stars, planets and galaxies in this universe must have originated at the centre and be spreading out, radiating away from that centre and from each other.  It also follows that when they were compressed at the centre the temperatures and density must have been fantastically high, just like we discussed yesterday.  And this, in a highly simplified nutshell, is where the idea of an exploding Singularity at the centre of the universe came from.

 

But can you see the problem with this conclusion?  Put simply, if you expect the universe to be a sphere without any evidence that it is one, then that skews your understanding, leading you to conclude that there must have been a Big Bang that exploded from a central point.  Your expectation is guiding your thinking instead of the evidence guiding your thinking.  Ok, we can forgive Einstein and the other scientists of the early 20th century because they just didn't know any better and they didn't have the tools to gather enough evidence to give them a better picture of reality.

 

There's also a logic problem with this exploding Big Bang model, Weezer.  If you say that everything exploded outwards from a single point then what is everything exploding INTO?  A pre-existing volume of space?  And if so, where did that come from?  This model of a spherically exploding Big Bang can't answer that and so the model creates as many problems as it solves.  Something is clearly wrong.

 

But a solution wouldn't be found for many decades.  And before we can tackle that we need to look at that second item from science history, one that is responsible for so many people misunderstanding the Big Bang and thinking of it as a kind of spherical explosion.  The two guys who were responsible for that are Stephen Hawking and Roger Penrose.  We'll look at their stuff once you're ok with this post.  Small steps.

 

The usual rule applies, Weezer.  If there's something puzzling you, just let me know and I'll try to explain.

 

 

Cheers,

 

Walter.

[pantheory]

7 hours ago, walterpthefirst said:

As for me, I prefer "simple" answers. Space is the distance between matter, beyond matter and field there would be no meaning to the word space, And if no changes ever occurred there would be no meaning to the word time. So both time and space can be simply defined, Of course more complicated definitions can easily be found. Without substance there could be no meaning to either time or space, If there was anything before a beginning entity, time, space, a field etc. then where did that come from? The simplest answer is that nothing came before that if one likes simplicity, then Occam's Razor is a good principle to consider.

 

https://www.britannica.com/topic/Occams-razor

 

 

Pantheory, could you please give a reason why reality should bend to your personal preference?

 

 

 

Walter.

 

This is not my preference, it is the preference of almost every cosmologist and scientist in the world, in every field of science. The simplest logical answer to a problem or question is always more likely to be true than more complicated answers, all else being equal. That's the principle of Occam's Razor.

 

Einstein once said in jest "make things (theory) as simple as possible but no simpler."

[walterpthefirst]

3 minutes ago, pantheory said:

 

This is not my preference, it is the preference of almost every cosmologist and scientist in the world. The simplest logical answer to a problem is always more likely to be true than more complicated answers, all else being equal. That's the principle of Occam's Razor.

 

Einstein once said in jest "make things (theory) as simple as possible but no simpler."

 

Not exactly true, Pantheory.

 

The preference for the simplest explanation must work hand-in-hand with the evidence.  Occam's Razor must not be used to dismiss or deny evidence.  Nor must it be used to reinterpret the evidence, simplifying it down to a level that is personally satisfying.  No cosmologist or scientist worth their salt does either of those things - dismissing and denying or simplifying for personal reasons.

 

And you've been told this before - by scientists.

 

https://www.physicsforums.com/threads/unraveling-the-big-bang-question-escaping-the-gravitational-pull-of-black-holes.215971/page-2#post-1738191

 

But who are you to decide how simple nature is? You can't decree that a theory is not simple enough to be correct The most you can do is, if presented with two theories making identical predictions, use Occam's razor to say that the simplest one is most likely to be true. Occam's razor says nothing about theories that make different predictions. I appear to be repeating myself here: is there something I am saying that you don't understand?

Reference: https://www.physicsforums.com/threads/unraveling-the-big-bang-question-escaping-the-gravitational-pull-of-black-holes.215971/page-2#post-1738191

 

 

Including the Prof, who is a scientist.

 

Suffering for the Good of the World - Page 5 - The Lion's Den - Ex-Christian.Net

 

 

But you persist in using Occam's Razor incorrectly.  Or putting it more accurately, using it in the way of your choosing.  So once again, you are putting your personal preference above proper procedure.

 

 

Walter.

 

[pantheory]

21 minutes ago, walterpthefirst said:

 

Not exactly true, Pantheory.

 

The preference for the simplest explanation must work hand-in-hand with the evidence.  Occam's Razor must not be used to dismiss or deny evidence.  Nor must it be used to reinterpret the evidence, simplifying it down to a level that is personally satisfying.  No cosmologist or scientist worth their salt does either of those things - dismissing and denying or simplifying for personal reasons.

 

And you've been told this before - by scientists.

 

https://www.physicsforums.com/threads/unraveling-the-big-bang-question-escaping-the-gravitational-pull-of-black-holes.215971/page-2#post-1738191

 

But who are you to decide how simple nature is? You can't decree that a theory is not simple enough to be correct The most you can do is, if presented with two theories making identical predictions, use Occam's razor to say that the simplest one is most likely to be true. Occam's razor says nothing about theories that make different predictions. I appear to be repeating myself here: is there something I am saying that you don't understand?

Reference: https://www.physicsforums.com/threads/unraveling-the-big-bang-question-escaping-the-gravitational-pull-of-black-holes.215971/page-2#post-1738191

 

 

Including the Prof, who is a scientist.

 

Suffering for the Good of the World - Page 5 - The Lion's Den - Ex-Christian.Net

 

 

But you persist in using Occam's Razor incorrectly.  Or putting it more accurately, using it in the way of your choosing.  So once again, you are putting your personal preference above proper procedure.

 

 

Walter.

 

 

If it didn't make sense it wouldn't be the simplest viable explanation, so error must be found within it and a better answer must be found. Again I was discussing the details of the BB theory a few decades ago.  If you think I am using Occam's Razor incorrectly or there is something wrong with my explanations and logic regarding evidence or observation, please explain the science or logical errors you believe are involved with my BB explanations above, since it is not my own theory.

 

 

[TABA]

22 hours ago, Weezer said:

I cannot handle 2 discussions at once.  Walter and I are on a roll, so wait until we finish.

Weezer started this topic and he asked the question.  @pantheory, would you mind standing aside as requested, until Walter and Weezer are done?  You can issue your rebuttal then, if you wish, or start a new thread.

 

Thanks for your cooperation!

 

 

[pantheory]

Just now, TABA said:

Weezer started this topic and he asked the question.  @pantheory, would you mind standing aside as requested, until Walter and Weezer are done?  You can issue your rebuttal then, if you wish, or start a new thread.

 

Thanks for your cooperation!

 

 

 

Of course I will.

[TheRedneckProfessor]

36 minutes ago, pantheory said:

The simplest logical answer to a problem or question is always more likely to be true than more complicated answers, all else being equal. That's the principle of Occam's Razor.

No.  It isn't.  The principle of Occam's Razor is that unnecessary facets should not be added to an explanation, if the explanation works without them.  Pluralitas non est ponenda sine necessitate (‘multiplicity ought not to be posited without necessity’) essentially means that when alternative hypotheses exist, the one requiring the fewest assumptions should be preferred.  This does not mean that the simplest explanation is more likely to be correct; only that, if an explanation has fewer unknowns or unexplainable factors, it should be considered the better explanation.  And that, once a reasonable explanation is given, additional unknowns or unexplainable factors should not be needlessly attached to it.

 

"Rain makes crops grow" is the simplest explanation; but that explanation fails to take into account soil pH, atmospheric conditions, environmental factors, and proper fertilization.  It is, therefore, not the most correct explanation, because it is too simple.  But an explanation that involves rain dances and sacrifices to the corn gods is also not the most correct explanation, because it posits facts not in evidence, assumptions, unknowns, and inexplicables.  In fact, this latter explanation raises more questions than it answers.  It is, therefore, too complicated.  It is these extraneous postulations that Occam's Razor seeks to eliminate, while keeping intact the core explanation that covers the necessary points of the subject.  Occam's Razor is the Goldilocks principle of the intellectual world, requiring that an explanation be neither too complicated nor too simple, but, rather, just right.  So, in this case: "Proper soil pH, conducive environmental factors, correct atmospheric conditions, fertilization and sufficient irrigation (without appealing to corn gods or performing rain dances) makes crops grow" is the correct explanation.  It covers all of the necessary points and can provide evidentiary support for each, while not positing further assumptions that lend nothing to the explanation itself. 

[◊ Weezer ◊]

I think I am with you so far Walter.  Does this fit in at this point?  I am thinking that space and time are both infinite.  
 

you have already helped me understand the theory of the Big Bang.  And I can see the possibility of holes in that theory.   Keep on a goin!  As my grandfather used to say. 

[walterpthefirst]

7 hours ago, Weezer said:

I think I am with you so far Walter.  Does this fit in at this point?  I am thinking that space and time are both infinite.  
 

you have already helped me understand the theory of the Big Bang.  And I can see the possibility of holes in that theory.   Keep on a goin!  As my grandfather used to say. 

 

 

Good call Weezer and made at just the right time.  

 

In my next post I was going to introduce the idea of space being infinite, so you've nicely pre-empted me there.

 

As to whether time is infinite... that's not so clear.

 

But it is something that we're going to look at later on.

 

So, hang in there.

 

I'll continue in a few hours.

 

 

Thanks,

 

Walter.

 

 

[walterpthefirst]

Right-ho Weezer,

 

 

Yesterday we saw how Einstein's expectation of a finite, spherical universe skewed his understanding and lead to the unworkable model of a Big Bang that exploded from a central point called the Singularity.  Today we're going to see how Stephen Hawking did something similar and how, if we undo his tinkering, the idea of an infinitely large universe works better.

 

Before we get into the meat of it I first need to say something about exploding stars.  When an extremely massive star, say twenty times the mass of our Sun, reaches the end of its life it doesn't go quietly.  Instead it collapses in upon itself very quickly and then the outer layers explode.  This is known as a supernova and they're the most powerful kind of explosions that we know of.  Four years ago lots of people thought that the star Betelgeuse (sounds like Beetlejuice) in the constellation Orion was going to go supernova... but no, it didn't.

 

Betelgeuse - Wikipedia   (The bright orange-red star, top left is Betelgeuse)

 

 

Anyway, what's this got to do with the Big Bang?  Well, a star is a sphere, isn't it?  It has a spherical outer surface and a centre.  So, when a star goes supernova it's core collapses inwards spherically, contracting down to a tiny point that becomes a black hole singularity.  Now if you could film this collapse happening and then play the film backwards, what would you see?   You'd see a fantastic amount of matter and energy exploding outwards from a central singularity - something like the way the spherical Big Bang was supposed to explode.

 

Ok, now I'll let Stephen Hawking tell the story in his own words.  This is from his international best seller, 'A Brief History of Time', chapter 8, page 7.

 

In 1965 I read about Penrose’s theorem that any body [massive star] undergoing gravitational collapse must eventually form a singularity. I soon realized that if one reversed the direction of time in Penrose’s theorem, so that the collapse became an expansion, the conditions of his theorem would still hold, provided the universe were roughly like a Friedmann model on large scales at the present time. Penrose’s theorem had shown that any collapsing star must end in a singularity; the time-reversed argument showed that any Friedmann-like expanding universe must have begun with a singularity.

 

For technical reasons, Penrose’s theorem required that the universe be infinite in space. So, I could in fact, use it to prove that there should be a singularity only if the universe was expanding fast enough to avoid collapsing again (since only those Friedmann models were infinite in space). During the next few years I developed new mathematical techniques to remove this and other technical conditions from the theorems that proved that singularities must occur. The final result was a joint paper by Penrose and myself in 1970, which at last proved that there must have been a big bang singularity provided only that general relativity is correct and the universe contains as much matter as we observe.

 

Let me simplify that a bit.

 

Hawking saw that Penrose's theory could describe the collapse of a massive star into a point-like singularity.  But that theory assumed that the universe in which this collapsing star existed was infinitely large.  As I mentioned yesterday, most scientists in the early part of the 20th century didn't expect the universe to be infinitely large.  Instead they expected it to be finite.  Anything finite must have a boundary and anything with that boundary must also have a centre.  

 

So, proceeding on that assumption Hawking tinkered with the theory, making the universe in which the massive star was collapsing into a finite one.  By doing that he could make the math describing the contracting sphere of the collapsing star work in reverse, describing the expanding sphere of an exploding Big Bang.  One going inwards and the other going outwards.  

 

Everything seemed to work and Hawking published the theory and put it into his best-selling book.  The rest is history.  Almost everyone accepted Hawking's idea that the universe began from a point-like singularity and then exploded outwards in what was called the Big Bang.  Science programs on tv, documentaries and videos then started showing exactly this happening on our screens.  BANG!  The whole universe coming into existence from a tiny point called the Singularity.

 

And this is why so many people still think of the Big Bang in this incorrect way, Weezer.

 

But, as we now know, that exploding Big Bang model makes as many problems as it solves.  And worse was to come in 1998.  In that year new data from outer space (too technical to go into any detail here) showed that the Hawking-Penrose theory was wrong.  Both scientists accepted this and discarded their theory as being refuted by new evidence.  

 

So what happens next?  Where do we go from here?  If the spherically exploding Big Bang theory is dead in the water, what has replaced it?  Your idea about the universe being infinitely large is where we go from here, Weezer.  That's the key to a better understanding and it also opens up the possibility that something preceded the Big Bang.  And if the Big Bang is preceded by something, then it can't be the true origin of everything, can it?  Maybe the universe isn't just infinitely large.  Maybe it's also infinitely old.

 

But that's enough for now.  I've given you a lot to digest.  Small steps.

 

 

Thanks,

 

Walter.

[TABA]

Walter, I hope you and Weezer don’t mind if I interject a question here.   Are they now saying the Big Bang never happened at all?  Or is it that something like the Big Bang happened but that it was not the true beginning of the universe, that something else preceded it?

[walterpthefirst]

2 hours ago, TABA said:

Walter, I hope you and Weezer don’t mind if I interject a question here.   Are they now saying the Big Bang never happened at all?  Or is it that something like the Big Bang happened but that it was not the true beginning of the universe, that something else preceded it?

 

 

That's ok, TABA.

 

 

I don't think Weezer will mind if I answer your questions.  It might even be helpful to the whole thread to do so.

 

First, let me make my position clear.  I'm describing orthodox cosmology here because Weezer asked the initial question.  That's the kind of cosmology I'm most familiar with but I don't necessarily hold to it like an article of faith.  I prefer to keep an open mind on the matter rather than become dogmatic.  There are other cosmological models out there and its possible that they could turn out to be viable.  That would depend on where the evidence takes us.

 

Now to your questions.

 

As far as mainstream, orthodox cosmology goes No, scientists are not saying that the Big Bang never happened.  What they are saying is that the earlier model, the point-like singularity and the spherical explosion - that didn't happen.  The evidence still points to an extremely hot and dense phase in the very earliest moments of the universe.  But the accepted view of how the expansion took place after has changed.  Weezer and I will be going into this later.

 

However, by doing away with that point-like singularity as the origin of everything scientists have now opened up the possibility that something preceded the hot dense phase I mentioned earlier.  Up to now in this thread we've only been talking about General Relativity as a way of describing the universe.  Einstein, Hawking and Penrose's work was all to do with GR.  But what about Quantum Mechanics (QM) ?  Any properly successful description of our universe and its origin MUST combine GR with QM.  So far its proved impossible to reconcile GR with QM in any way that works. 

 

But QM is giving us certain hints that something came "before" what we know as the Big Bang.  It's totally theoretical at the moment, but who knows where it will take us? 

 

And we also need to very careful in our use of words, TABA. 

 

Words like 'precede' and 'before' are used by us to describe the movement of time.  We easily grasp the concepts of past, present and future but it becomes difficult for us when time and space don't exist.  Do you see how easy it is to get tangled up here?  I wrote, "...when time and space don't exist."  But when is a word relating to time, so I'm tripping myself up here, in the act of trying to explain things.

 

I don't think it would help for me to say much more, TABA.  Hopefully I've answered your questions without confusing you too much.

 

 

Thanks,

 

Walter.

[TheRedneckProfessor]

Of some interest here, perhaps.  Bhim was a member some years back and held a Ph.D. in astronomy*.

 

*Edit:  Bhim's doctorate was actually in astrophysics, not astronomy. 

 

 

 

Excellent questions. Let me address them in order.
 

     
 

    "Does our universe expand in all directions equilaterally?" I'm guessing you meant "equally." Yes, the universe does expand equally in all directions. This is related to the observational principle known as Hubble's Law, which states that the recession velocity of distant galaxies is proportional to their distance from earth. In astrophysics we make this determination using a sort of stepping stone approach. The distance to nearby stars can be determined using the Method of Parallax. The same star, observed six months apart, will appear in a slightly different position in the sky because the Earth has moved with respect to the sun. Using Euclidean geometry and the known radius of the earth's orbit, we can deduce our distance from the star.
 

     

    (Source: http://spiff.rit.edu/classes/phys443/lectures/parallax/parallax.html)
 

     
 

    But, some stars are far enough away that we can't detect the parallax. That's where a certain class of stars known as Cepheid Variables comes in. A Cepheid Variable, as the name implies, is a "variable star," in that its brightness as viewed from earth - or magnitude, as we astronomers call it - varies with time. For Cepheids, that magnitude has a predictable period. It turns out that the luminosity of a Cepheid variable depends on its period, as shown in the below diagram:
 

     

    (Source: https://socratic.org/questions/why-is-a-cepheid-variable-star-referred-to-as-a-standard-candle)
 

     
 

    We don't know - a priori - how far away a distant star is. So a dim star that is very close to earth could have a smaller magnitude* than a bright star that is very far away. But in the case of Cepheid Variables, we can measure their distance and their magnitude, and thus infer their luminosity, i.e. the total amount of light emitted by the star (if you know how far away a star is and you know how much light you are receiving at Earth, you can know the luminosity). The period-luminosity relationship was determined by looking at Cepheid variables for which we have parallax measurements. That means that if a Cepheid is far enough away that we can't measure its parallax, we can still know its distance by measuring its period. That lets us look at Cepheids in other galaxies, and know how far away are those galaxies!
 

     
 

    Finally, we can look at Cepheids in galaxies that are at moderate distances, and determine their distances based on the periods of the Cepheids. We can also look at the energy spectra of light emitted from those galaxies, and look for spectral signatures. For example, we know that hydrogen electrons emit light at specific frequencies associated with electronic transitions. We know the frequencies by observing hydrogen in a lab. But if the hydrogen atoms are moving at high speeds close to that of light, those emission frequencies are shifted. By observing the new frequencies, we can know the speed of the hydrogen atoms. It turns out that if you look at galaxies that are sufficiently far away, the galaxies are always moving away from Earth. by looking at the nearby galaxies and determining their distance from the Cepheids, you can learn the mathematical relationship between distance and recession velocity. So now you can look at galaxies that are much further away - at distances where you can't resolve individual stars - but you can still know how quickly they are moving away from us based on the spectral signature. See the following diagram for an illustration of this effect:
 

     
 

     

    (Source: http://hosting.astro.cornell.edu/academics/courses/astro201/hubbles_law.htm)
 

     
 

    This effect isn't necessarily true for close by objects. For example, I am not receding from you, and the nearby Andromeda Galaxy is not receding away from us (in fact it is rushing toward us). But at larger distances where the expansion of the universe is more important, all galaxies move away from us.
 

     
 

    So to your second question: does this mean the Earth is the center of the universe? No! The interesting thing about this observation is that it is fully explainable by Einstein's Theory of General Relativity. Said theory shows that if you lived in one of those distant, receding galaxies, you would observe all galaxies moving away from you. It would appear that you were the center of the universe. You have probably heard that according to the Theory of General Relativity, space and time are viewed as a single entity, which can be likened to the malleable fabric of the universe. Think of spacetime as a balloon being inflated, and imagine making multiple marks on the balloon with a sharpie. As the balloon is inflated, an observer at each mark will see the other marks moving away from it. Yet no observer is at the "center" of the balloon, and we needn't even imagine the balloon expanding into anything else, because for the purpose of our analogy the surface of the balloon is all that matters (if you ever study differential geometry, this is referred to as a "Riemannian manifold").
 

     
 

    tl;dr. The universe is expanding in all directions from the vantage point of the Earth, and that does not mean the Earth is the center of the universe.
 

     
 

    *For historical reasons, magnitude is defined so that smaller numbers represent brighter objects. So -4 is brighter than 2 is brighter than 6, etc.
  https://www.ex-christian.net/topic/83698-the-universe/?do=findComment&comment=1226853

[TheRedneckProfessor]

36 minutes ago, TheRedneckProfessor said:

But, some stars are far enough away that we can't detect the parallax. That's where a certain class of stars known as Cepheid Variables comes in. A Cepheid Variable, as the name implies, is a "variable star," in that its brightness as viewed from earth - or magnitude, as we astronomers call it - varies with time. For Cepheids, that magnitude has a predictable period. It turns out that the luminosity of a Cepheid variable depends on its period, as shown in the below diagram:
 

 

 

 

 

[◊ Weezer ◊]

5 hours ago, walterpthefirst said:

Maybe the universe isn't just infinitely large.  Maybe it's also infinitely old.

 

Yes.    That thought occurred to me a couple of years ago. 
 

keep on a goin!

[walterpthefirst]

Very well, Weezer.

 

But that's two different things.  An infinitely large universe.  An infinitely old universe.  Today I'll present the current evidence for the first.

 

 

As mentioned before, a universe of a finite size and volume must have a boundary and centre.  But unless it pops into existence fully grown to its current dimensions it has to expand to get there.  And if it does so from a centre then we are back with the problems I described earlier.  First, what is it expanding into?  Second, all that energy can't just spring into existence from nowhere, violating the laws of thermodynamics.  And third, the best theory describing a spherical universe expanding from a centre, the one formulated by Hawking and Penrose, failed and was refuted by new evidence.

 

So, if the universe isn't a finite size the only other option is to go with the idea that it is infinitely large.  An infinite universe goes on forever without any kind of boundary or edge.  There is no centre.  No location is any closer to or any further away from the centre because there isn't one.  No location is any closer to or any further away from the boundary because there isn't one. Space extends infinitely far in every direction.  Pick a direction.  Any direction.  If you travel in a spaceship in that direction you will never return to where you started.  You travel in a straight line... forever. 

 

 

Now please hold that thought about straight lines going on forever, Weezer.

 

Shape of the universe - Wikipedia

 

 

 

Now don't panic!  It's not as bad as it looks!

 

These three shapes are the three main possible shapes of the geometry of the universe, as described by the equations of Einstein's General Relativity.  From top to bottom they are known as a Closed, an Open and a Flat universe.  The geometry of each one affects what happens to a straight line drawn on them.  A Closed universe is finite in size, with a definite boundary and a centre - just like the universe that Einstein originally theorized and like the universe that Hawking and Penrose theorized.  Two parallel straight lines drawn on it will not stay parallel, they will eventually converge.

 

If you don't believe me Weezer, you can test this for yourself.  Get an Atlas of the world and draw two parallel lines, starting at the equator and going North.  It's a good idea to have them widely separated so start one on the equator in South America and the other on the equator in Africa.  What happens when you extend the lines further and further north?  They reach the north pole. 

 

On a flat map the north pole is shown as a line running across the top of the world map.  But on a globe the north pole is a single point, located north of Greenland and Canada.  All lines of longitude on a map converge on the north and south poles.  The two lines you've drawn are also lines of longitude.  Like all the other lines of longitude they start off parallel at the equator and then gradually converge at the poles.  

 

So, in a Closed universe with a boundary and centre two parallel straight lines always converge.  This is a geometric proof that a Closed universe cannot be infinitely large.  That's because, as I said earlier, in an infinitely large universe straight lines go on forever.  And two parallel straight lines would never converge.  They would stay parallel to each other... forever.

 

 

And what has this got to do with our universe?

Well, as of today our universe has been measured to have no curvature and to be Flat, to a confidence value of 99.98%.  This means, as far as we can tell by measuring the observable universe, we do not live in a Closed or Open universe.  That's because both the geometry of those types of universe are curved.  In a Closed universe two parallel line always converge and in an Open universe they always diverge.  But we can detect no visible curvature at all in our universe - to a confidence value of 99.98%

 

This is a strong line of evidence to that we live in a Flat and therefore infinitely large universe.

 

I can give you another line of evidence that our universe is infinite if you'd like Weezer.  Just let me know.  Or, if you're ok with just this example I can move on to discuss a universe that might infinitely old.  Just give me the shout.

 

 

 

Thanks,

 

Walter.

 

 

 

[◊ Weezer ◊]

2 hours ago, walterpthefirst said:

 

This is a strong line of evidence to that we live in a Flat and therefore infinitely large universe.

 

I can give you another line of evidence that our universe is infinite if you'd like Weezer.  

 

I don't see that it is flat.  It has no shape.  It runs forever in every direction, no matter where you start.  I don't think I need further evidence.

 

Keep on a goin!

[walterpthefirst]

13 minutes ago, Weezer said:

I don't see that it is flat.  It has no shape.  It runs forever in every direction, no matter where you start.  I don't think I need further evidence.

 

Keep on a goin!

 

I can see your point, Weezer.

 

Yes, the universe does seem to run forever in every direction.

 

Flat is what the scientists say when they mean it looks infinite and runs away forever in every direction.  

 

That's they're technical way of saying what you said.

 

 

Tomorrow I'll take a shot at trying to explain how the everything might be infinitely old.

 

Could get a bit trippy!

 

 

Thanks,

 

Walter.

[◊ Weezer ◊]

         

[Hierophant]

This is infinitely over my head. I have no way to conceive of a flat universe, or what that really means.

[◊ Weezer ◊]

1 hour ago, Hierophant said:

This is infinitely over my head. I have no way to conceive of a flat universe, or what that really means.

The word "flat" confused me at first.  Did you see the below? ( Space goes on forever in all directions)

8 hours ago, Weezer said:

I don't see that it is flat.  It has no shape.  It runs forever in every direction, no matter where you start.  

Evidently scientist don't always use the most descriptive and common terminology for what they are trying to explain. 

[◊ Weezer ◊]

8 hours ago, walterpthefirst said:

 

Tomorrow I'll take a shot at trying to explain how the everything might be infinitely old.

 

If you mean that time is infinite, I already believe that.  Well, at least the future.  It is always ahead of us, and who knows how far back it goes.  But go ahead with your explanation if you think I need it.