Is the Universe Really Expanding?

[WannabeNewton]

Except you don't need the 4-space -- Euclidean 3-space is sufficient to describe a flat expanding cosmology (with trivial topology).

That is what I don't get. The Friedmann metric with k = 0 involves Euclidean 4 - space and Euclidean 3 - space would be a space - like hypersurface of it so how is it sufficient to describe an expanding cosmology with nothing but that space - like hypersurface?

 

[bapowell]

That is what I don't get. The Friedmann metric with k = 0 involves Euclidean 4 - space and Euclidean 3 - space would be a space - like hypersurface of it so how is it sufficient to describe an expanding cosmology with nothing but that space - like hypersurface?

We've been discussing the spatial part of the geometry in this discussion! Sorry if that was not made clear. But yes, good catch!

 

[GODISMYSHADOW]

You need not know how big the universe is to realize it is expanding. Einstein deduced the universe could not be static, it had to either be expanding or contracting. Hubble confirmed it was indeed expanding, causing Einstein to commit his biggest blunder - withdrawing his cosmological constant idea.

Does that say anything about the Schwarzschild radius? If we observe the universe is expanding, does that mean we're not sitting in a black hole?

 

[Physics_Kid]

Does that say anything about the Schwarzschild radius? If we observe the universe is expanding, does that mean we're not sitting in a black hole?

interesting point you make. i was pondering the "is expanding" statement that is made about the Uverse. i find galaxy red shift to be not enough info that the Uverse itself is expanding as it only suggests the item is moving away from the observer (or the "moving" object isn't moving relative to its localize space-time, but space-time itself is) . my argument is that you must be able to measure the current "size" of the Uverse and then take same measurement at some time in the future then read the diff to be able to conclude "is expanding", etc. but my argument suggests a instantaneous finite universe. even with the balloon argument (the expanding fabric of space-time) has a finite "area" or "volume" at any given time. i may be completely wrong but to me it makes more sense that the Uverse is not infinite, how can it be if space-time started at a single point?

 

[Physics_Kid]

sorry for bringing back an old thread, but its relevant.

so if the theory of "big bang" is correct and we agree the uverse is expanding, this implies the density of uverse is also decreasing at a fixed rate (unless we can show acceleration in the expansion).

are there any consequences (in math or physics) for space-time to become infinitely less dense?

is it possible that the uverse (however its mechanics are defined) has fixed density?

 

[bapowell]

are there any consequences (in math or physics) for space-time to become infinitely less dense?

What does it mean for space-time to have density?

 

[Drakkith]

are there any consequences (in math or physics) for space-time to become infinitely less dense?

is it possible that the uverse (however its mechanics are defined) has fixed density?

Note that when we say the density of the universe is decreasing we are talking about the density of matter and radiation within the universe.

 

[Chronos]

What does it mean for space-time to have density?

It means nothing.

 

[Physics_Kid]

It means nothing.

are we sure? i mean, if you lasso the uverse you are essentially lasso'ing what we know as space-time. perhaps time itself has no relationship to "density", but it is related to the universe as a whole? can time extend past the edges of the unverse?

but, to my question, any implications for density to become infinitely small?

 

[Drakkith]

are we sure? i mean, if you lasso the uverse you are essentially lasso'ing what we know as space-time.

You cannot lasso the universe so your comparison isn't meaningful.

perhaps time itself has no relationship to "density", but it is related to the universe as a whole? can time extend past the edges of the unverse?

There are no edges to the universe as far as we know.

but, to my question, any implications for density to become infinitely small?

Sure, it just means density becomes zero and you have a vacuum.

 

[Akaisora]

You need not know how big the universe is to realize it is expanding. Einstein deduced the universe could not be static, it had to either be expanding or contracting. Hubble confirmed it was indeed expanding, causing Einstein to commit his biggest blunder - withdrawing his cosmological constant idea.

I am still learning and my knowledge in the said subject is limited, however, I have this idea of a "cosmological constant" that calculates the expansion/acceleration of space-time - and the universe in general.

So that idea has been debunked? The universe expands at a changing rate instead of a static constant? Could it be something related to the distribution of energy and mass?

 

[bapowell]

So that idea has been debunked? The universe expands at a changing rate instead of a static constant? Could it be something related to the distribution of energy and mass?

The "constant" in the "cosmological constant" is not in reference to the expansion rate -- it refers to the fact that it appears as a constant (times the metric tensor) in the Einstein Equations. This means that it behaves as a constant energy density. A constant energy density results in an accelerating spacetime. Due to the recentish discovery that the universe is in fact presently accelerating, there is renewed interest in the potential presence of a cosmological constant.

 

[dexterdev]

If something is expanding...what is there there outside of the expansion volume...

 

[cristo]

If something is expanding...what is there there outside of the expansion volume...

In terms of the universe, nothing: the spacetime of the universe itself is expanding.

 

[Physics_Kid]

There are no edges to the universe as far as we know.

i think you have written a real catch-22/enigma. for anyone to say "its expanding" that implies you are able to measure the boundaries at least twice. but here you say there are no edges, so how is it possible to conclude expansion?

i know we have indirect measurements of very far away stuff seemingly moving away at very high speeds, but this alone cannot conclude expansion, because after-all, space itself may just be a really really big thing and we can only observe small pieces of things inside moving around...?

 

[bapowell]

i think you have written a real catch-22/enigma. for anyone to say "its expanding" that implies you are able to measure the boundaries at least twice. but here you say there are no edges, so how is it possible to conclude expansion?

A balloon can expand, and this can be measured by assessing the growth in distance between points fixed to the balloon, and yet it has no edges.

 

[Drakkith]

i think you have written a real catch-22/enigma. for anyone to say "its expanding" that implies you are able to measure the boundaries at least twice. but here you say there are no edges, so how is it possible to conclude expansion?

No, it implies that we are able to make a measurement of objects within expanding space.

i know we have indirect measurements of very far away stuff seemingly moving away at very high speeds, but this alone cannot conclude expansion, because after-all, space itself may just be a really really big thing and we can only observe small pieces of things inside moving around...?

Science disagrees. Would you like to know why?

 

[No-where-man]

No, it implies that we are able to make a measurement of objects within expanding space.



Science disagrees. Would you like to know why?

It's all about interperetation, it is more like that space does not expand but the distance between objects expand.

 

[No-where-man]

A balloon can expand, and this can be measured by assessing the growth in distance between points fixed to the balloon, and yet it has no edges.

They key problem is there is outside of the balloon where and how the balloon can expand (weak analogy), it means outside of the universe as well.

 

[No-where-man]

The balloon analogy is a 2D example of our 3D world. In the balloon analogy, we live on the surface -- there is no inside! The actual universe would be the surface of a 3-sphere.

If there is no inside, how it is to suppose to expand when there is nothing what would make the balloon or the universe expand, something is obviously pushing us to expand.

 

[No-where-man]

I did address your previous post. Let me be more clear (also, keep in mind that this discussion assumes from the outset that the universe is globally positively curved...it might not be.) Here:Because the region you are proposing does not have spherical topology. A positively curved 3D universe has the shape of a 3-sphere, with the 3D universe corresponding to the surface of the sphere. The 4-space is indeed mathematically superfluous, but it helps us visualize. Here's an example: a torus is readily visualized as the 2D surface of a donut. We can easily visualize the torus by picturing a donut in everyday 3D space. But we don't need the 3rd dimension -- we can define a torus using only 2 dimensions by starting with a 2D surface and assigning rules for how the edges are to be connected (think of the Asteroids Atari game -- that is an example of bona fide toroidal topology, and it is perfectly defined on just your 2D screen.) So, getting back to the universe. Supposing that the universe is positively curved and has 3 spatial dimensions, then we are dealing with a 3D volume that has spherical topology. Geometrically, this is the surface of a 3-sphere. Now, we don't need the 4th dimension to fully define the topology or geometry (just as we didn't need the 3rd for the torus), but it helps us visualize -- especially since the 4D space becomes the 3D ambient space when we consider the balloon analogy.

Every time I look at every model, I always ask what's outside that model, because even model as well as the universe has its size and diameter, and if something like the universe with size can exist in nothing (since there is absolutely nothing outside the universe)-which means no space-zero size, than it's not science.
You cannot have anything that has size (and requires space) to exist in something (which is actually absolute nothing/nothingness) that has no space and no size, this is absolutely impossible.

 

[Drakkith]

It's all about interperetation, it is more like that space does not expand but the distance between objects expand.

There is no difference between saying space expands and carries objects with it and saying the geometry of space causes the distance between objects to grow. The former is simply a commonly used way of putting it that allows people to visualize and understand it without getting into the math.

They key problem is there is outside of the balloon where and how the balloon can expand (weak analogy), it means outside of the universe as well.

It's just an analogy and should not be taken too far. Trying to say our models of the universe are incorrect simply because an analogy doesn't make perfect sense isn't going to get you anywhere.

If there is no inside, how it is to suppose to expand when there is nothing what would make the balloon or the universe expand, something is obviously pushing us to expand.

Yes, the geometry of space is "pushing" us, though it is not really a force.

Every time I look at every model, I always ask what's outside that model, because even model as well as the universe has its size and diameter, and if something like the universe with size can exist in nothing (since there is absolutely nothing outside the universe)-which means no space-zero size, than it's not science.
You cannot have anything that has size (and requires space) to exist in something (which is actually absolute nothing/nothingness) that has no space and no size, this is absolutely impossible.

The model represents the universe. There is nothing outside that model whether or not you believe there should be.

 

[No-where-man]

There is no difference between saying space expands and carries objects with it and saying the geometry of space causes the distance between objects to grow. The former is simply a commonly used way of putting it that allows people to visualize and understand it without getting into the math.
It's just an analogy and should not be taken too far. Trying to say our models of the universe are incorrect simply because an analogy doesn't make perfect sense isn't going to get you anywhere.

Yes, you are right about this.

Yes, the geometry of space is "pushing" us, though it is not really a force.

Well, according to a model, but when I read it's expanding like 13 km/s in a million light years, that sounds little fishy-I actually thought it's much faster than this. It has to be mentioned that this space is not really "empty", so yes there are "forces"in this seemingly empty space (like quantum vacuum fluctuations).

The model represents the universe. There is nothing outside that model whether or not you believe there should be.

There is outside of the model, which we cannot model it, and that's why it's considered nothing, because it's outside our ability to model anything, since we cannot see it or detect it, or measure it (but it's not nothing because of the same reasons big bang hypothesis isn't wrong, just because analogy is not perfect).

The same as you previously said, trying to say our models of the universe are incorrect simply because an analogy doesn't make perfect sense isn't going to get you anywhere; this can be said for the big bang hypothesis model, just because we don't have a model for outside of the known universe, it's wrong to say there is not anything beyond the model of metric expansion of space, there is something like space-which is 100% irrefutably proven and these are 100% proven facts (empty or not, otherwise universe would never be created in the first place and it would not be possible to expand, and the model of the universe would never be created in the first place which is 100% irrefutably proven facts), but we cannot use anything since it is beyond our reach of detection.

Since a scientist is always looking for any hard and irrefutable scientific evidence to support his/her hypothesis especially about the big bang hypothesis, than he/she should be critical when it comes inflation-something that can never be proven, you cannot really scientifically test or do any scientific experiment, if inflation hypothesis is correct or not.

 

[bapowell]

Since a scientist is always looking for any hard and irrefutable scientific evidence to support his/her hypothesis especially about the big bang hypothesis, than he/she should be critical when it comes inflation-something that can never be proven, you cannot really scientifically test or do any scientific experiment, if inflation hypothesis is correct or not.

Inflationary expansion can absolutely be empirically verified. Why do you say different?

 

[No-where-man]

Inflationary expansion can absolutely be empirically verified. Why do you say different?

No, it can't, because none has detected the inflation process and nobody can ever detect the inflation process, since there was nobody to witness this event.

 

[bapowell]

No, it can't, because none has detected and nobody can detect it, since there was nobody to witness the event.

So what you're saying is that we can't scientifically investigate any event that occurred in the past? Suppose you walk into a room to find a broken glass on the floor in a puddle of water. You appear to be saying that we have no reason to suspect with any level of confidence that the broken glass previously held water, simply because there was nobody there at the time to witness it?

We happen to have quite direct evidence of early universe dynamics, very much like the broken glass example. This is how science is done: we make an observation, develop a model that explains the observation, and go about empirically testing the model in as rigorous a fashion as possible. All of these steps are undertaken in our investigation of the early universe.

If you are so ready to commit inflation to the dustbin of non-science, then include the whole of cosmology that occurred up until a second ago. Add in all of evolutionary biology, geology, and the field of criminal forensics. I think you'll find that your view of how science is done is fantastically restrictive.

 

[No-where-man]

So what you're saying is that we can't scientifically investigate any event that occurred in the past? Suppose you walk into a room to find a broken glass on the floor in a puddle of water. You appear to be saying that we have no reason to suspect with any level of confidence that the broken glass previously held water, simply because there was nobody there at the time to witness it?

We happen to have quite direct evidence of early universe dynamics, very much like the broken glass example. This is how science is done: we make an observation, develop a model that explains the observation, and go about empirically testing the model in as rigorous a fashion as possible. All of these steps are undertaken in our investigation of the early universe.

If you are so ready to commit inflation to the dustbin of non-science, then include the whole of cosmology that occurred up until a second ago. Add in all of evolutionary biology, geology, and the field of criminal forensics. I think you'll find that your view of how science is done is fantastically restrictive.

The problem is we are dealing with entire universe and with its beginnings, in CSI you see forensics experts which enter the room and collect the evidence, in this case of the expanding universe you cannot go into the universe and collect the evidence since there is no way we can get there and investigate it to actually prove that inflation has occurred or not, all we have is observation from telescopes and that's about it, but the actual evidence/evidences is/are missing (like measurement and detection of the actual event).

I actually truly hope that inflation hypothesis is the correct one, but saying that this is definitely, absolutely 100% proven is simply wrong.
Cheers.

 

[bapowell]

The problem is we are dealing with entire universe and with its beginnings, in CSI you see forensics experts which enter the room and collect the evidence, in this case of the expanding universe you cannot go into the universe and collect the evidence since there is no way we can get there and investigate it to actually prove that inflation has occurred or not, all we have is observation from telescopes and that's about it, but the actual evidence/evidences are missing.

How is making precise measurements of the temperature fluctuations of the cosmic microwave background not collecting evidence about the dynamics of the early universe? How is catching photons in a telescope any different than dusting for fingerprints (aside from the obvious literal distinction?)

 

[No-where-man]

How is making precise measurements of the temperature fluctuations of the cosmic microwave background not collecting evidence about the dynamics of the early universe? How is catching photons in a telescope any different than dusting for fingerprints (aside from the obvious literal distinction?)

But that does not actually tell us and more importantly it does not directly or indirectly prove that inflation did or did not occur.

 

[Nugatory]

But that does not actually tell us and more importantly it does not directly or indirectly prove that inflation did or did not occur.

Measurements and experiments don't prove theories; they disprove competing theories.

 

[bapowell]

Measurements and experiments don't prove theories; they disprove competing theories.

While Popper's theory is the only logically-sound approach to scientific inquiry, quite frankly, nobody actually does science this way because the program is not useful for showing us how the universe actually works. What are we to do with the pool of unfalsified theories? For practical applications, we still need to confirm the predictions of these competing theories, and we still need to apply inductive reasoning in developing them. While never amounting to a logically-sound proof, confirmation of prediction remains an integral part of the scientific enterprise for the simple fact that it works. When the LHC found the Higgs, did you remark, "Aha! They have falsified the theory that there is no Higgs!", or did you say something closer to "Aha! The Higgs exists!"

 

[bapowell]

But that does not actually tell us and more importantly it does not directly or indirectly prove that inflation did or did not occur.

Sure, and science is not in the business of furnishing proofs (only disproofs -- see Nugatory's post and my reply). Instead, you should think in terms of evidence in favor of one theory over another: surely, the observations of the cosmic microwave background provide evidence (both direct and indirect) in favor of inflation.

 

[No-where-man]

Sure, and science is not in the business of furnishing proofs (only disproofs -- see Nugatory's post and my reply). Instead, you should think in terms of evidence in favor of one theory over another: surely, the observations of the cosmic microwave background provide evidence (both direct and indirect) in favor of inflation.

CMBR does not provide anything, inflation can actually never be proven, the time when universe was so small than it got really, really big, a factor of at least 10^78 in volume according to inflation hypothesis-this kind of expansion in such small time by such a huge factor cannot be proven by any means.
And everybody should stay of this.
It's like you're having only psychology and psychological behavior and profile of the suspect, but there is no way you can prove it's him/her because the crucial direct DNA evidences which connect the suspect have never been found-this is exactly the same situation with inflation hypothesis only instead of psychological behavior you have only observation (which is equivalent to psychology and psychological behavior and profile of the suspect in forensic sciences in identifying suspects as criminals/killers and etc.) and that's it, plus evidences can also be completely misleading and instigate us on completely wrong interpretation and deduction (after all we're dealing with entire universe here, things like collecting the evidence, or to be more precise, collecting only circumstancial evidences and deduction are much tougher, much more complicated and much more complex when it comes to understanding entire universe and everything in it)-this is exactly the case with the Big Bang hypothesis.

As well as they say Big bang was explosion of space-time, but space is not something that can be created or simply explode-only if it's truly empty (like the void), besides all that energy in the big bang that is still creating and expanding entire universe-which is btw, outside the universe, has come from somewhere-outside of the universe/outside of the big bang in outside space (empty or not).

The geometry of space is not what is pushing galaxies away, actually you are saying geometry, but in the real universe there is no geometry it is energy and forces that are left from the big bang explosion in seemingly empty space that are present in the space-quantum fluctuations, but space alone is not doing anything, everything is happening in space itself, space alone is not doing anything.
The big bang explosion was not explosion of space and time, big bang explosion was explosion in space, it could not explode and expand if there was no outside space.
Cheers.

 

[Bandersnatch]

No-where-man, perhaps you could step back and ask yourself(or tell us if you know) what is your goal here?

It certainly isn't learning, as you have rejected all answers so far provided without any other reason than you not liking them.

Neither it is teaching, at least not of mainstream science, as you hold views running contrary to and incompatibile with not only modern cosmology, but methodology of science. You reject definitions, call theories hypotheses, assert impossibilites, and dismiss evidence.

I hope it is not bullying other members into agreeing with your personal theory, as this is not allowed as per the rules of the forum you had agreed on when you signed in.

 

[No-where-man]

No-where-man, perhaps you could step back and ask yourself(or tell us if you know) what is your goal here?

It certainly isn't learning, as you have rejected all answers so far provided without any other reason than you not liking them.

Neither it is teaching, at least not of mainstream science, as you hold views running contrary to and incompatibile with not only modern cosmology, but methodology of science. You reject definitions, call theories hypotheses, assert impossibilites, and dismiss evidence.

I hope it is not bullying other members into agreeing with your personal theory, as this is not allowed as per the rules of the forum you had agreed on when you signed in.

I'm not creating any theory or anything like, I don't believe in anything in any god, theory or hypothesis (I'm basically a nihilist), my main focus is on inflation if it can be scientifically proven, I answered why is this impossible and that's pretty much it.
I mentioned quantum fluctuations as well, what am I saying that inside the expanding universe, there is no such thing as empty space, especially if it can "stretch" as rubber-that's all scientific.

My only criticism comes when you say there is nothing outside the universe, because we cannot create a model "outside the universe".
Everybody is aware that universe does not expand in absolutely nothing, it's something, because like I said in 71st post:

"Every time I look at every model, I always ask what's outside that model, because even model as well as the universe has its size and diameter, and if something like the universe with size can exist in nothing (since there is absolutely nothing outside the universe)-which means no space-zero size, than it's not science.
You cannot have anything/something that has size and diameter (and it means that it requires space) to exist and expand in "outside the universe" (since according to a model there is no space or anything else outside the universe, actually there is absolutely nothing outside the universe) that has no space and no size-this is absolutely impossible".
That's all.
All the best.

 

[Drakkith]

I'm not creating any theory or anything like, my focus is on inflation if it can be scientifically proven, I answered why is this impossible and that's pretty much it.

And your answer is just plain wrong. Inflation is supported by real evidence.

I mentioned quantum fluctuations as well, what am I saying that inside the expanding universe, there is no such thing as empty space, especially if it can "stretch" as rubber-that's all scientific.

There is nothing scientific about your posts. You have provided no evidence to support your claims nor have you even brought forth a reasonable argument. Everything you've said boils down to "because I said so".

I think you should read this: http://en.wikipedia.org/wiki/Scientific_method

My only criticism comes when you say there is nothing outside the universe, because we cannot create a model "outside the universe".
Everybody is aware that universe does not expand in absolutely nothing, it's something, because like I said in 71st post:

And your reasoning is wrong, as has been explained before. You insist that something exists outside the universe. The universe. That which everything exists within. IT JUST DON'T ADD UP!

 

[No-where-man]

And your answer is just plain wrong. Inflation is supported by real evidence.

What evidence, where it was actually directly detected inflation where, when, how? You didn't see it or detect it through observation.

There is nothing scientific about your posts. You have provided no evidence to support your claims nor have you even brought forth a reasonable argument. Everything you've said boils down to "because I said so".

I think you should read this: http://en.wikipedia.org/wiki/Scientific_method

No, everything boils down to what you and your models say so, they may very good explain the universe but not what's outside of it.
It's interesting you mention that there is nothing scientific, quantum fluctuations are scientific you obviously never heard of them. Quantum fluctuations are the reason why empty space is not really empty.
And you call this un-scientific? You obviously do not follow science at all.

And your reasoning is wrong, as has been explained before. You insist that something exists outside the universe. The universe. That which everything exists within. IT JUST DON'T ADD UP!

My reasoning is right and it is based on collecting evidences and facts (yours is based on opinion that is not supported by any evidence or a fact), if none else sees the mistake when you say there is nothing outside the expanding universe, than you should back to school.
I said before and I'll say once more:

"Every time I look at every model, I always ask what's outside that model, because even model as well as the universe has its size and diameter, and if something like the universe with size can exist in nothing (since there is absolutely nothing outside the universe)-which means no space-zero size, than it's not science.
You cannot have anything/something that has size and diameter (and it means that it requires space) to exist and expand in "outside the universe" (since according to a model there is no space or anything else outside the universe, actually there is absolutely nothing outside the universe) that has no space and no size-this is absolutely impossible".
If none realizes this crucial mistake and what is here absolutely impossible to achieve, than it's inevitable to go back to basics at the school.
That's all.
All the best.

 

[bapowell]

What evidence, where it was actually directly detected inflation where, when, how? You didn't see it or detect it through observation.

This definition of "evidence" is so stringent, I think you'll find that virtually all human knowledge falls victim to it. It is manifestly unscientific, as people have mentioned many times on this thread. Usually when one person (you) sees some obvious flaw with a theory/methodology that experts across the ages have understood not to be a problem, the overwhelmingly likely explanation is that you are under a misapprehension rather than the that whole theory is wrong, lacks evidence, etc. Unless, of course, you are Einstein.

My advice is to listen carefully to what the knowledgeable people on the forums have to say, rather than staunchly defending some preconceived and incorrect view of science and the universe.

 

[No-where-man]

This definition of "evidence" is so stringent, I think you'll find that virtually all human knowledge falls victim to it. It is manifestly unscientific, as people have mentioned many times on this thread. Usually when one person (you) sees some obvious flaw with a theory/methodology that experts across the ages have understood not to be a problem, the overwhelmingly likely explanation is that you are under a misapprehension rather than the that whole theory is wrong, lacks evidence, etc. Unless, of course, you are Einstein.

My advice is to listen carefully to what the knowledgeable people on the forums have to say, rather than staunchly defending some preconceived and incorrect view of science and the universe.

You don't have to have Einstein's or Hawking's IQ or above them, to see what is wrong with that reasoning when it comes to saying there is nothing outside the universe because our models say so.

And I do listen to all of you (although, you might think it is the opposite), it's one of the reasons why I am asking what evidences exist for inflation.
The same reason is why there is not literally/absolutely nothing outside the universe, there is some kind of space (even if it's empty space/the void), but it is absolutely impossible to detect outside the universe, it's equally absolutely impossible to detect the inflation.
All the best.

 

[bapowell]

You don't have to have Einstein's or Hawking's IQ or above them, to see what is wrong with that reasoning when it comes to saying there is nothing outside the universe because our models say so.

It's not so much that our models "say so" as it is a result of the differential geometry of curves and surfaces. Curvature, including time-dependent expansion, can be consistently defined for manifolds without the need to embed them in higher-dimensional space. If we take general relativity to be our theory of large-scale gravity, then this amounts to the interpretation that the universe as a 3+1 dimensional manifold need not exist in a higher dimensional space. Of course, there could be such a higher-dimensional space, but it is not required by consistency of the theory. Nobody is forced into this position because our models just happen to be this way.

 

[bapowell]

but it is absolutely impossible to detect outside the universe, it's equally absolutely impossible to detect the inflation.
All the best.

Obtaining observational evidence for inflation is not the same thing as literally "detecting" it, just as observing the Grand Canyon and hypothesizing its formation from water erosion does not amount to "detecting" the prehistoric Colorado River while it was in the act of carving out the rock. Science does not proceed via a requirement of absolute detection in the positivist sense. You seem to persist in this claim and it's simply not how science works.

 

[No-where-man]

It's not so much that our models "say so" as it is a result of the differential geometry of curves and surfaces. Curvature, including time-dependent expansion, can be consistently defined for manifolds without the need to embed them in higher-dimensional space. If we take general relativity to be our theory of large-scale gravity, then this amounts to the interpretation that the universe as a 3+1 dimensional manifold need not exist in a higher dimensional space. Of course, there could be such a higher-dimensional space, but it is not required by consistency of the theory. Nobody is forced into this position because our models just happen to be this way.

The irony is I'm the one who actually does say there are only 3 dimensions (plus time). Not long ago I came into a "fight" where I was actually defending big bang hypothesis and and its 3+1 dimension description (yes, I know none would believe me this here on these forums). It's simply not needed to exist higher dimension than 3d+time, and actually 3d dimensional manifold is capable being absolutely infinite without going into any higher dimensions.

However, when I the BB hypothesis I'm not talking about higher dimensions or anything like it I'm simply saying that there is no way that there was nothing before and beyond the big bang.
If by definition and models and whatever else, the BB started the universe, it may started this 3d space (which is not empty at all), but it did not start space in which it occurred.
You can call this empty space/black void, but according to physics, if I understand correctly space is merely the distance between the objects, I'm fine with this.

But also it would not be possible without space where this objects are moving away from each other, expanding universe ma perhaps create its own space while it expands, however, that outside of the universe space is already omnipresent, and this is why the universe and everything inside the expanding universe and every object or light, including this "space-time" in the universe expands-it cannot expand if there is nothing outside the universe.

Also, the other problem is that we can only observe visible part of the universe with our most powerful telescopes, we cannot observe entire universe (beyond the visible part of the universe), since there is no way we can detect it and observe it, so the question still remains how exactly large is entire universe, not just this observable part of the universe, and if the expansion of the universe itself is real.

It's similar like Earth, if Earth was expanding everything inside the horizon would expand, but it can expand because there is outside space in which Earth can expand into.

Plus energy of the BB that created entire universe and everything in it, is the one thing that is outside of the expanding universe (and it created Big Bang and entire universe afterwards).
All the best.

 

[No-where-man]

Obtaining observational evidence for inflation is not the same thing as literally "detecting" it, just as observing the Grand Canyon and hypothesizing its formation from water erosion does not amount to "detecting" the prehistoric Colorado River while it was in the act of carving out the rock. Science does not proceed via a requirement of absolute detection in the positivist sense. You seem to persist in this claim and it's simply not how science works.

That's all true, but again it's much easier to do the above mentioned than to prove the inflation, you would first have to scan entire universe and all of its parts and only than create some conclusions about it, but it would not be evidence, Colorado river at least leaves some evidences, but inflation left zero evidence.

I do know that:
The main (and original) reason for the proposal of inflationary theory was the horizon problem. That is, the fact the the universe is so incredibly homogeneous and isotropic despite the fact that some parts of the universe are apparently too far away to have exchanged energy. Inflation in the early universe is a powerful explanation for this intriguing observation. Also of note is the flatness problem, which inflation also helps address.

There are of course various other theories to explaining this problems, not in any way related to inflation, such as the varying speed of light (VSL) theory. These are however under active research and still not widely accepted.

The standard arguments are not yet conclusive. The horizon problem, or the homogeneity problem, can be explained by assuming that the initial condition is homogeneous, without assuming that causal contact in the early universe has smoothed out inhomogeneities. You may object that a homogeneous initial condition is "unnatural", but since we know so little about the big bang singularity, there's nothing conclusive that can be said. The monopole problem is only a problem if you think monopoles exist, which has no empirical evidence so far. The curvature problem, again, is a "naturalness" problem, but we lack a precise definition of naturalness given our inability to understand the big bang singularity.

The key phrase is 'detectable'. In order to be scientific about it, It must be detectable, observable.
Cosmologist suggests universe might not be expanding after all:
http://phys.org/news/2013-08-cosmologist-universe.html

How about the dark matter:
http://phys.org/news/2012-07-cosmology-group-evidence-dark-filament.html
All the best.

 

[Drakkith]

However, when I the BB hypothesis I'm not talking about higher dimensions or anything like it I'm simply saying that there is no way that there was nothing before and beyond the big bang.
If by definition and models and whatever else, the BB started the universe, it may started this 3d space (which is not empty at all), but it did not start space in which it occurred.
You can call this empty space/black void, but according to physics, if I understand correctly space is merely the distance between the objects, I'm fine with this.

The Big Bang Theory does not say what started the universe, merely that it expanded from a very dense state.

But also it would not be possible without space where this objects are moving away from each other, expanding universe ma perhaps create its own space while it expands, however, that outside of the universe space is already omnipresent, and this is why the universe and everything inside the expanding universe and every object or light, including this "space-time" in the universe expands-it cannot expand if there is nothing outside the universe.

And you have evidence of this? You've perhaps seen other universes expanding into pre-existing space? Surely you cannot expect us to believe you simply because you say so.

Also, the other problem is that we can only observe visible part of the universe with our most powerful telescopes, we cannot observe entire universe (beyond the visible part of the universe), since there is no way we can detect it and observe it, so the question still remains how exactly large is entire universe, not just this observable part of the universe, and if the expansion of the universe itself is real.

If this is a "problem", what is it a problem for? We can easily look our observable universe and see that it is expanding.

It's similar like Earth, if Earth was expanding everything inside the horizon would expand, but it can expand because there is outside space in which Earth can expand into.

Earth is not the universe. You cannot simply extrapolate what happens here on Earth and try to apply it to the universe. It just doesn't work that way. It's similar to how things at the smallest scale of atoms and fundamental particles do not work the same way that the they appear to work here at our scale. That's why we rely on observation, experiments, and a generous helping of math.

 

[Drakkith]

The key phrase is 'detectable'. In order to be scientific about it, It must be detectable, observable.
Cosmologist suggests universe might not be expanding after all:
http://phys.org/news/2013-08-cosmologist-universe.html

From the article:

Unfortunately, Wetterich's theory can't be tested because of the relative nature of mass. Everything we are able to see has a mass that is relative in size to everything else. Thus if it's all growing, we wouldn't have anything to measure it against to see that it's happening.

This fails by your own admission.

How about the dark matter:
http://phys.org/news/2012-07-cosmology-group-evidence-dark-filament.html
All the best.

What about it?

 

[No-where-man]

The Big Bang Theory does not say what started the universe, merely that it expanded from a very dense state.

And that very hot and very dense state is called energy.

And you have evidence of this? You've perhaps seen other universes expanding into pre-existing space? Surely you cannot expect us to believe you simply because you say so.

I'm not saying anything, you're the one who is saying that universe came from nothing, not me.
There is no such thing as nothing, this is not my belief, it's a 100% proven fact, it is your belief that there was absolutely nothing outside the big bang-it would never be possible for the big bang to exist in the first place if there is no space outside of the big bang and the energy of the big bang would never be able to expand in the first place-if there is no outside space (I'm not talking about the inside space (and time) which is supposedly created in the big bang explosion).

If this is a "problem", what is it a problem for? We can easily look our observable universe and see that it is expanding.

No, you can't know if it's truly expanding, it does not mean anything, in order to actually see and observe the actual expansion of the universe, you would have to wait million years to see and observe if anything has moved away from us, since the speed of expansion is very small.

Earth is not the universe. You cannot simply extrapolate what happens here on Earth and try to apply it to the universe. It just doesn't work that way. It's similar to how things at the smallest scale of atoms and fundamental particles do not work the same way that the they appear to work here at our scale. That's why we rely on observation, experiments, and a generous helping of math.

Maybe they don't work the same, but it shows and proves that there is no such thing as you say "there is nothing outside the universe".
All the best.

 

[No-where-man]

From the article:

Unfortunately, Wetterich's theory can't be tested because of the relative nature of mass. Everything we are able to see has a mass that is relative in size to everything else. Thus if it's all growing, we wouldn't have anything to measure it against to see that it's happening.

This fails by your own admission.

It doesn't mean it's incorrect it only means it's impossible to measure because of the mentioned reasons.

What about it?

Nothing really, it's a good clue to determine what is exactly dark matter and what it is made of.
All the best.

 

[Drakkith]

And that very dense state is called energy.

No, it is not. It was a hot bath of radiation and matter.

I'm not saying anything, you're the one who is saying that universe came from nothing, not me.
There is no such thing as nothing, this is not my belief, it's a fact, it is your belief that there was absolutely nothing outside the big bang-it would never be possible for the big bang to exist in the first place if there is no space outside of the big bang.

You haven't been paying much attention then. It's been repeatedly said that our models and theories do not require that the universe be embedded within a higher dimension of space or that it exist within pre-existing space. At no point do any of them make a firm statement about whether or not it does.

No, you can't red **** doe not mean anything, in order to actually see and observe the actual expansion, you would have to wait million years to see if anything has moved away from us, since the speed of expansion is quite small.

I assume you mean redshift. And yes, it does mean something. Don't dismiss evidence just because you do not like it.

Maybe they don't work the same, but it shows and proves that there is no such thing as you say "there is nothing outside the universe".
All the best.

We don't say that, nor does it have anything to say about whether or not nothing exists outside the universe.

 

[Drakkith]

It doesn't mean it's incorrect it only means it's impossible to measure because of the mentioned reasons.

Nothing really, it's a good clue to determine what is exactly dark matter and what it is made of.
All the best.

Don't link stuff that is irrelevant to the thread, please.

 

[No-where-man]

No, it is not. It was a hot bath of radiation and matter.

And radiation and matter are forms of energy.

You haven't been paying much attention then. It's been repeatedly said that our models and theories do not require that the universe be embedded within a higher dimension of space or that it exist within pre-existing space. At no point do any of them make a firm statement about whether or not it does.

You obviously did not read mine answers above, I never said anything about the higher dimensions, I actually think they are totally unnecessary-i was not talking about higher-dimension space, I was talking about space outside the universe, but not with higher dimensions-my apology for this misunderstanding.

I assume you mean redshift. And yes, it does mean something. Don't dismiss evidence just because you do not like it.

I don't dismiss it, but read shift does not really prove anything. Also, what do we actually see are the objects moving away from us, not the space itself.

The reason why I'm saying this because the fact remains you see this universe now with red shift, and it will stay the same in static form for like a little less than million years-if the speed of expanding universe is truly correct 13 km/s in one million years, than we would have to wait that long to actually see the movement, and of course the red shift will change, but observing now with red shift and next several thousands of years nothing will change since the speed of expansion is too small.

We don't say that, nor does it have anything to say about whether or not nothing exists outside the universe.

If the universe is truly infinite and everything happens inside of it than there is no outside, if entire universe was truly created in the big bang, than it expands in some outside space (and this could also be empty space/black void).
And without any higher dimensions.
All the best.