Space expansion

[Anonymous No.6428429]

Is space expansion bullshit?

There is no question that the further away a galaxy the faster it recedes from us (as described in Hubble's law), but why do people explain this observation by saying that space itself stretches or is created between galaxies? Especially when space is not some substance independently defined from the distance measurements we make, so saying that space is created between is the same as saying that the distance between the two galaxies increases, it does not explain anything.

If galaxies recede from a given point at a rate proportional to their distance away from it, then from any point it will appear that galaxies recede at a rate proportional to their distance as well. There is no need to invoke that weird-ass concept of space expanding, stretching or being created, all we have to say is that galaxies keep on going due to inertia with the speed the big bang imparted them (slowing down due to gravity and accelerating due to dark energy).

You might think there is a problem with that interpretation because far galaxies recede from us faster than light, but the thing is we don't observe these galaxies in our inertial reference frame (we see them as they were billions of years ago) so the postulate of special relativity that the speed of light is the same in all inertial frames doesn't hold here.

I honestly don't understand how or why they came up with space expansion in the first place when they noticed that galaxies recede with a velocity proportional to their distance

[Anonymous No.6428443]

>>6428429
It just sounds cooler.

[Anonymous No.6428448]

Guys, hey guys.. what if, what if the universe isn't expandng, our galaxy is just slowing down... whoa

[Anonymous No.6428473]

>>6428429
>all we have to say is that galaxies keep on going due to inertia with the speed the big bang imparted them

Thing is, the galaxies at the edge of the universe seem to be moving away from us at something like four times the speed of light.

Space be whack, yo.

[Anonymous No.6428472]

>>6428429
because if you do an energy balance in general relativity you find space must expand.

[Anonymous No.6428471]

>>6428448
Then if you looked in the other direction you would see a bunch of galaxies coming for you, which thankfully is not the case

[Anonymous No.6428504]

>>6428472
General relativity says how energy curves spacetime locally, where does it say how energy expands space globally?

>>6428473
>Thing is, the galaxies at the edge of the universe seem to be moving away from us at something like four times the speed of light.
Which I addressed in the OP (and it's closer to three times actually)

[Anonymous No.6428548]

>>6428504
take the Einstein equations, put in a scale factor and some matter, elemenate shit with symmetries such as homogeneity and the energy component becomes -(a'/a)^2 + k + p = 0 (with some constants and maybe is p^2, cant remember anymore) with p the energy density in space, a the scaling factor, a' = da/dt and k the curvature. it tells you how space expands locally due the the energy at that point, since space is homogenous space expands everywhere thus we can work with averages and assume a is constant over space and you can solve for a as a function of the average density of the universe. note that a'/a also happens to be equal top the Hubble constant, so assuming a flat universe (k=0) we have that the hubbel constant is proportional to the average energy density ion the universe. just read a general relativity textbook for the parts i left out.

[Anonymous No.6428572]

>>6428429
>why do people explain this observation by saying that space itself stretches
... because all the other half-assed explanations (like yours) ignores observable data like redshift.
Lrn2cosmology

[Anonymous No.6428589]

>>6428548
I've never worked out the mathematics of general relativity but I'll definitely look into it. I thought mass/energy only modified the curvature of spacetime, how does this scale factor enter the picture? Is it something that appears in Einstein's original equations, or in its solutions, or do you know if it was added in after Hubble's observations of galaxies' recessional velocity?

[Anonymous No.6428600]

>There is no need to invoke that weird-ass concept of space expanding, stretching or being created, all we have to say is that galaxies keep on going due to inertia with the speed the big bang imparted them

Why are they all moving away from us. Why should we be the center?

>we don't observe these galaxies in our inertial reference frame
That doesn't matter. A ball isn't in my inertial reference frame but it obeys relativity. You mean local intertidal frame but if the universe is not expanding then a local inertial frame extends across the universe ignoring gravitation. So special relativity should hold. Why doesn't it?

[the only not-op here No.6428605]

>There is no question that the further away a galaxy the faster it recedes from us (as described in Hubble's law), but why do people explain this observation by saying that space itself stretches or is created between galaxies?
The only way an object can move faster is A) if it is imparted energy or 2) the space on which it exists is expanding outwards. There is no observed or theoretical phenomenon to explain the increase in rate other than dark energy or the cosmological constant being involved in an acceleration of matter apart.

>Especially when space is not some substance independently defined from the distance measurements we make
Yes it is, though it gets modified from Relativistic theories to be more confounded by the relative velocities of travelling objects and the mass/energy they have.
>so saying that space is created between is the same as saying that the distance between the two galaxies increases, it does not explain anything
It explains why things are further apart than they should be given any other known properties of matter-light.

>If galaxies recede from a given point at a rate proportional to their distance away from it, then from any point it will appear that galaxies recede at a rate proportional to their distance as well.
Again, there is no theoretical or observational effect to explain this phenomenon other than space having an existence and it is expanding and dark energy accelerates mass in terms of Special Relativity.

>There is no need to invoke that weird-ass concept of space expanding, stretching or being created, all we have to say is that galaxies keep on going due to inertia with the speed the big bang imparted them (slowing down due to gravity and accelerating due to dark energy).
Then propose a mathematically accurate explanation of the phenomenon which also can accurately describe the orbits of planets, microwave background radiation, quantities of observable mass and energy, the spectrum of lights, etc, and I will gladly follow

[Anonymous No.6428607]

>>6428589
Expanding universe solutions were worked out before.

[Anonymous No.6428611]

>>6428572
>observable data like redshift
Which is readily explained by the fact we don't observe the light we receive in the same reference frame that it was emitted in, which avoids to resort to half-assed explanations where the photon loses energy like a salmon going up a river

[Anonymous No.6428625]

>>6428611
It's not a half assed explanation if you understood anything about general relativity.
What isn't readily explained is why if it was just velocity everything would appear to move away in such an ordered manner. It also doesn't explain more distant effects of the redshift distance relation.

[Anonymous No.6428628]

>>6428600
>Why are they all moving away from us. Why should we be the center?
Like I said, if you spend time thinking about it you will realize that if galaxies recede from a given point (any point) at a velocity proportional to their distance, then from any other point galaxies will also appear to recede at a velocity proportional to their distance. The point chosen in the first place doesn't have to be us.

>That doesn't matter. A ball isn't in my inertial reference frame but it obeys relativity.
I didn't explain myself properly there, I meant we observe these galaxies in a non-inertial frame (because we aren't observing them now but how they were billions of years ago)

[Anonymous No.6428630]

>>6428605
>You might think there is a problem with that interpretation because far galaxies recede from us faster than light, but the thing is we don't observe these galaxies in our inertial reference frame (we see them as they were billions of years ago) so the postulate of special relativity that the speed of light is the same in all inertial frames doesn't hold here.
It holds in all reference frames, by definition. You have no authority over modifying where it applies, unless you can show your theory that it changes based on time/location/distance/something explains the same amount more simply, more stuff more accurately, or at least a smaller set more accurately.

>>6428429
Velocity is equal to distance divided by time. We had two choices, either say that space has time zones where it exists at a different rate than the rest of the universe (which is inconsistent with the observation that ALL space around us seems to be accelerating the same proportion based on distance), or two, increase the distance it travelled (which is consistent if it is happening between all objects in the universe).


A better proposition to make, is not that the distance between objects is increasing, but that say light expands in proportion to the time it takes light to travel, that way a single wave is red-shifted not by the acceleration of distant objects, but is stretched by how long it has traveled. I personally believe this as certain far-off objects, if we believe they ARE that distant based on red-shifting, can be overwhelmingly larger or overwhelmingly brighter than ANY known explanation allows, even though local objects are more accurately explained.

[Anonymous No.6428646]

>>6428630
Also, if light is expanding, than this explains away dark matter, as objects would not be as large as they appeared to be, so gravity would be larger in proportion to the objects.

The power of light is also explained, as the quantum nature of photons only permits the units of energy. If a single unit of energy loses energy as it travels (a quantized explanation of red shifting), while still only traveling the same distance, then it would appear objects are inherently brighter than closer objects, because we are receiving a larger quantity of photons than would be expected if an object is further apart - and this again is consistent with "far off" objects seeming to be outputting more energy than theories are currently describing.

[Anonymous No.6428654]

>>6428628
>Like I said, if you spend time thinking about it you will realize that if galaxies recede from a given point (any point) at a velocity proportional to their distance, then from any other point galaxies will also appear to recede at a velocity proportional to their distance. The point chosen in the first place doesn't have to be us.
So why would such an arrangement form out of the Big Bang.

> I meant we observe these galaxies in a non-inertial frame (because we aren't observing them now but how they were billions of years ago)
Delays exist in special relativity, that still doesn't explain why it would be allowed. Why do you get velocities greater than c?

[Anonymous No.6428659]

Dude, they are like trying there best to explain what they see with their telescopes. If they can't explain what they see now, they won't get the money for bigger and better telescopes.

[Anonymous No.6428661]

>>6428589
you insert the scale factor to simplify the model so that you can find a solution, you assume that the geometry remains the same except for the time dependance which is in one common scale factor for every direction.

[Anonymous No.6428663]

>>6428630
>that way a single wave is red-shifted not by the acceleration of distant objects, but is stretched by how long it has traveled.
This is tired light cosmology. It doesn't explain the Tolman surface brightness test, it doesn't explain the uniformity of the CMBR or time dilation in supernovae and quasars.

>can be overwhelmingly larger or overwhelmingly brighter than ANY known explanation allows
Such as?

>>6428646
You're going to need to explain what you mean. I don't think that works at all.

[Anonymous No.6428664]

>>6428605
>There is no observed or theoretical phenomenon to explain the increase in rate other than dark energy..
And why wouldn't dark energy be something that imparts energy to these objects?

>Yes it is
Care to expand on this? That's the point that troubles me the most, how is space defined exactly?

>Again, there is no theoretical or observational effect to explain this phenomenon other than space having an existence and it is expanding
Yes there is, consider the big bang made things move this way then inertia takes care of the rest. If one object moves at velocity V1 = H.D1 at distance D1 from a reference point at time t0, and a second object moves at velocity V2 = H.D2 at distance D2 from the same reference point at same time t0, then after a time T object 1 will be at distance D1(1+H.T) and object 2 at distance D2(1+H.T), and the ratio of velocities is conserved then there will still be a proportionality between velocity and distance.

>Then propose a mathematically accurate explanation of the phenomenon which also can accurately describe the orbits of planets, microwave background radiation, quantities of observable mass and energy, the spectrum of lights, etc
As far as I know the expansion of space isn't involved in describing the orbits of planets. The microwave background radiation can be explained as I said without resorting to an expansion of space, and the shifted spectrum is explained by the fact we don't observe the light in the same reference frame as the one it which it was emitted.

[Anonymous No.6428670]

>>6428659
Piss off with the conspiracy nonsense.

[Anonymous No.6428681]

>>6428654
>So why would such an arrangement form out of the Big Bang.
Why wouldn't it? We don't know how the Big Bang came to be in the first place. If you will you can explain that initial arrangement with the expansion of space (whatever that space is), but I don't see how that expansion of space has to keep going to explain what we observe now.

>Why do you get velocities greater than c?
The limit of c is valid in inertial frames only, non-inertial frames allow for greater than c values.

[Anonymous No.6428685]

>>6428664
>And why wouldn't dark energy be something that imparts energy to these objects?
How would it?

>The microwave background radiation can be explained as I said without resorting to an expansion of space, and the shifted spectrum is explained by the fact we don't observe the light in the same reference frame as the one it which it was emitted.
You keep saying that as if it means something. Why is redshifted at all?

[Anonymous No.6428694]

>>6428681
>Why wouldn't it? We don't know how the Big Bang came to be in the first place. If you will you can explain that initial arrangement with the expansion of space (whatever that space is), but I don't see how that expansion of space has to keep going to explain what we observe now.
So your model assumes there is some reason that the universe would behave like this. The expanding universe explains why, you have a question mark. Your model has no predictive power. The expanding universe explains the non-linearity of the redshift distance relation with ease, your model must be fudged and you assume there must be a reason.

>The limit of c is valid in inertial frames only, non-inertial frames allow for greater than c values.
You're deflecting. Why is it non-inertial. The delay due to light doesn't do it so why isn't special relativity applicable?

[Anonymous No.6428696]

>>6428504
Except that the postulates of relativity do still hold or you have a great deal of other spectral data to explain.

Another problem which you entirely ignored is that a universe where this was the case would have a significant dependence upon what direction you look as well as distance for what velocity you would get.

[Anonymous No.6428719]

>>6428685
>>6428694
>>6428696
I will have to think about it some more before giving an answer, I can't think straight anymore. Probably you are right on most points.

I guess the thing that prompted me to make this thread in the first place is what the fuck is space? They say it expands but what is the rigorous definition of that space they are referring to when they say it expands? If space is the distance between two objects then how does saying space expands explain anything more than saying the distance between the two objects increases?

[Anonymous No.6428732]

>>6428719
>They say it expands but what is the rigorous definition of that space they are referring to when they say it expands?
The nature of space is written in general relativity. It tells us how it acts and what it can do. Expansion is one of those things. There is no physical theory of space just like there is no theory on the physical nature of the wavefunction, only speculation.

>If space is the distance between two objects then how does saying space expands explain anything more than saying the distance between the two objects increases?
Because it naturally predicts a Hubble flow and it naturally explains the high redshift behavior of the Hubble diagram. It explains more.

[Anonymous No.6428739]

>>6428670
"Methinks the lady doth protest too much."

[Anonymous No.6428744]

>>6428739
>I can't support my beliefs in a scientific debate but I swear everyone else is wrong.

You're probably one of those nutters who belies in anti-gravity, the aether or the electric universe.

>>>/x/

[Anonymous No.6428749]

>>6428732
>There is no physical theory of space
But will there ever be a physical theory of space or is it just an imaginary intermediate that we use to make sense more easily of the observations? It makes me think of the electric and magnetic fields: theory says charges generate electric/magnetic fields then other charges react to these fields, but what really happens is charges react to other charges, the fields are only mathematical intermediates. Isn't that the same thing with space?

[Anonymous No.6428753]

>>6428663
Thank you for the tired light/brightness test info, I think I disagree with their conclusions (for a flat geometry+"constant" expansion), but I haven't looked through papers. I will surely read them.

[Anonymous No.6428762]

>>6428749
>Isn't that the same thing with space?
Perhaps. With electromagnetism we have the benefit of QED which gives a hint of a possible physical interpretation we have nothing like that for gravity and space. We can only try to work towards a more physical interpretation if one exists.

[Anonymous No.6428773]

>>6428663
Forgot to add:
The Hubble Ultra Deep Field has a bunch of galaxies which are seemingly like four times too large or bright for their own good. AFAIK I've heard of a lot of the 10+ billion "year older" galaxies and such showing properties like brightness, average star density (based on the distance-brightness-mass-lifetime relations), etc being incompatible with current models.

>>6428664
>As far as I know the expansion of space isn't involved in describing the orbits of planets.
Special Relativity. It's like someone trying to argue human-based increases in greenhouse gases aren't causing an average increase in warming on the planet, but then they go out, drive a car, read nutrition labels, use a computer, etc. They are all mechanically consistent in the same scientific theory (though SR and Quantum Mechanics have their... unifying issues)

>>6428749
If you can manage to find the book "Geons, Black Holes, and the Quantum Foam" the author goes into detail about how every theory he learns he tries to rewrite to explain EVERYTHING. Once you learn gravity, maybe charges are actually some sort of microscopic gravity/antigravities. Then you run into problems, so you learn more. You learn charge theories, which eventually transform into fields and matter. Maybe everything uses fields to interact? Well that quite doesn't work right. Well maybe everything is matter. Well maybe everything is photons. Etc etc ad infinitum, every time we learn some new mathematical model or tool to explain behavior, we will inherently try and use it as much as we can, the phrase embodied in the metaphor "when all you have is a hammer, everything looks like a nail".

It just so happens fields are SO GODDAMN USEFUL for explaining phenomenon that we will inherently use them for new phenomenon, and get pretty good results. Roger Penrose is a theoretician who uses geometric interactions, as opposed to fields (some difference exists I don't know), but, continued

[Anonymous No.6428777]

>>6428762
Okay. Well thank you for the helpful discussion, it feels good once in a while to talk with people who at least sound like they know what they're talking about. I'll read the whole thread again with a clear head tomorrow, then I'll study general relativity in depth and come back with a rebuttal...or maybe not.

[Anonymous No.6428780]

>>6428773
>The Hubble Ultra Deep Field has a bunch of galaxies which are seemingly like four times too large or bright for their own good. AFAIK I've heard of a lot of the 10+ billion "year older" galaxies and such showing properties like brightness, average star density (based on the distance-brightness-mass-lifetime relations), etc being incompatible with current models.
This does not say what you claimed it did. Current models are models of galaxy formation not cosmology. To understand how bright a galaxy should be you need to know how they evolve and that is not understood. This does not invalidate cosmology.
There is nothing in this that means anything is brighter or larger than can possible be explained.

>Special Relativity.
You mean general relativity.

[Anonymous No.6428781]

>>6428773
but geometry is an assload harder to conceptualize and deal with than fields, so it's a much less developed interpretation of interactions and things. The most unified theory, M-Theory, has the four normal space-time dimensions we work with, but an additional 7 spatial dimensions. In order to get any useful results out of it we have to throttle it the fuck and back just to try and get relevant results out, and even then, we are more trying to get it down to match existing observations (it does), whereas getting to what new things it proposes is ridiculous harder to find. Although mathematically I believe M-Theory can get good results on simple gravitational and quantum properties, trying to wrangle the equations into more complex scenarios is so ridiculously awful people wonder if we can even get phenomenon from it that we'll be able to observe. I think strings are smaller than the orders of magnitude between solar systems and quantum particles or something, so to even simulate basic interactions we need preposterous amounts of calculations.

[Anonymous No.6428785]

>>6428780
Galactic formation models are based on presumptions from Cosmology though. It's like the spectrum of hot objects coming from classical mechanics causes the ultraviolet catastrophe. Yes, classical mechanics isn't cosmology nor formation theories, but when the star doesn't match with your theories, you have an problems that affect the core principles.

And yeah, GR, not SR.

[Anonymous No.6428795]

>>6428785
>Galactic formation models are based on presumptions from Cosmology though.
No. What cosmological parameter describes supernovae feedback in nuclear starbursts? What cosmological principle describes the exchange of gas and plasma between the inter stellar medium, the curium-galactic medium and how AGN jets affect this?
Galaxy formation contains so much more than cosmology. It is a hugely complex area.

It's nothing like Rayleigh–Jeans because there are so many parameters going into it.

There are so many parts to galaxy formation you cannot possibly say just the cosmological parameters are wrong.

[Anonymous No.6428839]

>>6428773
>If you can manage to find the book "Geons, Black Holes, and the Quantum Foam" the author goes into detail about how every theory he learns he tries to rewrite to explain EVERYTHING

That sounds like exactly the kind of book I'm looking for, I'm always pondering on scientific theories myself and how they came to be devised rather than accepting everything they claim as dogmatic facts. It took me years to realize what was off with F=ma, I used to wonder how Newton managed to find such a simple and compelling law about the universe, but then I realized that it merely defined the concept of force since force is not rigorously defined outside of that relation. It allows to describe observations and make predictions only because the expressions of forces (gravitational, electrostatic, ...) have been chosen so as to fit in the relation F=ma. The fundamental aspect is that matter accelerates matter, and the fundamental relations the ones such as "a mass M accelerates matter at the rate GM/r^2 towards it", not that matter generates a force which is GmM/r^2 and then the acceleration is GM/r^2 because we have the law F=ma.

I suspect there might be something similar with the concept of space that makes me feel uneasy, but until I know more about general relativity I'll refrain from making claims. Thanks for the book, will read

[Anonymous No.6428867]

>>6428839
Force is the first derivative of momentum, it tells you how the momentum varies, that's how it's defined. F=ma defines momentum which is a hugely important quantity in physics.

>the fundamental relations the ones such as "a mass M accelerates matter at the rate GM/r^2 towards it"
What about a block on a table? It's not accelerating but gravity hasn't disappeared. You cannot always say "gravity accelerates stuff". Forces allow meaningful discussion in static cases.

[Anonymous No.6428920]

>>6428867
>F=ma defines momentum
Well yes its a definition, not a fundamental concept. You measure velocities and you measure masses by measuring changes in acceleration, you don't measure momentum nor force directly.

>What about a block on a table? It's not accelerating but gravity hasn't disappeared. You cannot always say "gravity accelerates stuff"
It is not accelerating downwards because the electromagnetic repulsion between the atoms of the table and the atoms of the block accelerates it upwards by the same amount.

>Forces allow meaningful discussion in static cases.
Sure it allows meaningful discussion but it hides what really happens by adding a layer of abstraction.

[Anonymous No.6428928]

>>6428920
>not a fundamental concept
It is because it's a conserved quantity. Velocity is not.

>You measure velocities and you measure masses by measuring changes in acceleration, you don't measure momentum nor force directly.
You can't measure acceleration directly either.

>It is not accelerating downwards because the electromagnetic repulsion between the atoms of the table and the atoms of the block accelerates it upwards by the same amount.
But it's not accelerating at all hence why that term isn't used.

[Anonymous No.6428994]

>>6428928
>It is because it's a conserved quantity. Velocity is not.
Then I guess we are disagreeing on what a fundamental concept is. What makes a conserved quantity a fundamental concept? To me a fundamental fact (shall I say postulate) is that things behave the same way whether they are in one location in space or another, all other things being equal (or how they say it that the laws of physics are invariant with respect to spatial translation); the conservation of momentum being a consequence of this I don't find is as fundamental. Besides I call velocity a fundamental concept because without velocity there would be no change, no laws of physics and we wouldn't even be here to talk about it. Momentum is a product of mass and velocity (in the classical limit), how can it be more fundamental that velocity itself?

>You can't measure acceleration directly either.
That's right you have to measure the rate of change of distance over time and then the rate of change of that, but same remark than for velocity, without acceleration the universe would be quite predictable and we still wouldn't be here to talk about it.

>But it's not accelerating at all hence why that term isn't used.
It is still accelerating, the electrons from the table and from the block are not in the same state than they were before the block was there because they have to keep counteracting the acceleration of gravity. For us the acceleration of the block is null, but for the electrons there is something going on. You can call it a force if you want.

[Anonymous No.6431226]

>>6428471
Oh my god! They're coming right for us!
>*BLAM*

[Anonymous No.6431307]

>>6428448
Our galaxy is slowing down, or the speed of light is slowing down?

[Anonymous No.6432983]

is big bang real?
how does superinflation work?
how many kinds of fish are in the ocean?