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j_sum1
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Thanks WG48.
I am insufficiently knowledgeable to critique the statement properly or even to understand all the terms. But it does strike me as a frame of
reference problem leading to a different interpretation rather than any substantial change in fact. In other words, we are talking about curved
spacetime. We could either interpret observations as expansion of space or dilation of time. The two could be considered isomorphic.,
At least that is my reading of what you posted.
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wg48temp9
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Quote: Originally posted by j_sum1  | Thanks WG48.
I am insufficiently knowledgeable to critique the statement properly or even to understand all the terms. But it does strike me as a frame of
reference problem leading to a different interpretation rather than any substantial change in fact. In other words, we are talking about curved
spacetime. We could either interpret observations as expansion of space or dilation of time. The two could be considered isomorphic.,
At least that is my reading of what you posted. |
Your welcome.
Conflating different coordinate system or reference frames is not open to interpretation its simple wrong, as is ignoring the velocity addition
formula of special relativity. Then inventing a mechanism (stretching/expanding space) to account for it is bonkers (very unscientific) Einstein must
be turning in his grave LOL
Here is an other snippet from the conclusion of a different paper:
"The common belief that the cosmological redshift can only be explained in terms of the stretching of space is based on conflating the properties of a
specific coordinate system with properties of space itself. This confusion is precisely the opposite of the correct frame of mind in which to
understand relativity"
From https://arxiv.org/pdf/0808.1081.pdf
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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Chalo
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It is perhaps useful to first pause briefly to review what a redshift of z = 5 actually means, and why it matters.
Redshift, z, is simply a straightforward way to quantify the ratio of the observed wavelength (λo) to the emitted wavelength (λe) of light:
(1) 1+z=λo /λe
If we interpret z of 5 as due to space stretching, (usual interpretation) this means that when light left that galaxy, the universe was 1+5=six times
smaller than it is presently. Imagine drawing the sine waves on a rubber sheet, then stretching the sheet sixfold, the distance between peaks appears
larger.
If however we were to interpret it literally as due to a recession velocity, the velocity you would need to see the same increase in observed
wavelength would be
6=sqrt((1+v/c)/((1-v/c)), comes out to velocity of 0.946 C.
Needless to say a galaxy is far too hefty a thing to possibly be moving at essentially light speed. Consider what the momentum would be, and its
apparent mass and gravity. Time would also be stretched by the Lorenz factor. None of this is observed.
Also consider that redshift behaves as if everything in the universe was moving directly away from everything else, on a straight line connecting
their centers, so shft is function of distance alone rather than direction. If it were a literal doppler effect, the direction of movement would be as
important as distance or speed. Unless we were the center of the universe everything was moving away from, the recession rate and threfore the
redshift would depend far more on the angle we view the object with respect to a line to the "center of universe" than it would on distance. But if
space itself stretches, there is no center, and shift becomes a function of distance alone in all directions.
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j_sum1
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| Quote: Originally posted by Chalo |
Needless to say a galaxy is far too hefty a thing to possibly be moving at essentially light speed.
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Is there some rule that states that "hefty" objects are limited in their velocity? I think this kind of statement adds to confusion.
Of course space expansion can explain the observed phenomenon: red shift measured for objects in every direction. But time dilation could also be use
to explain this.
So the question then becomes, do there exist concrete reasons to prefer one explanation over the other? I am not aware of any. The scientific
consensus seems to be on space expansion, but that does not necessarily mean the question is resolved, or can ever be resolved.
I like papers like this one because they cause us to reflect and properly consider assumptions we have held and the foundation for what we believe.
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wg48temp9
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Chalo:
You suggestion that a galaxy can not have a velocity (relative to the earth) almost at velocity of light because it would have an enormous momentum
apparent mass and gravity seems unreasonable. I know of no such limitation. Consider the cosmic microwave background (CMB) radiation has a red
shift 1,100 that that about 0.999999 (from memory) of the speed of light. Given the big bang created all the energy/mass of the whole observable
universe and the un-observable universe beyond that must also an enormous number. Its should be noted that momentum is vector quantity so if he
universe is isotropic the total momentum would be zero.
The red shift is the observational confirmation of the velocities. The cosmological model assume the galaxies are kinematic/belistic. There is nothing
in them about space expanding.
Your 1+5=six calculation uses the cosmological doppler formula which is the calculation used in the cosmological models that use a version of
proper distance (see the last two papers I posted). The physicist Leonard Susskind states that the FLRW cosmological model is only applicable for
velocities much less than the velocity of light and for low gravity. I suspect that means the models are linear without the quadratic terms of
relativity.
I recommend Stanford's series of lectures on cosmology by Leonard Susskind see https://www.youtube.com/watch?v=P-medYaqVak.
Nobel Laureate Brian Schmidt also has a series of lectures on cosmology but I could not find them. Curiously in one lecture he explains that the
superluminal velocities of FLRW models does not contravene special relativity because locally the velocity of galaxies is alway less than the
velocity if light.
j_sum1:
Yes the expanding space thing is the consensus though why with the obvious (to me) incompatibility with special relativity.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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wg48temp9
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I noticed a question while visiting a physics forum. The question was "is the observable universe a black hole". He/she said that the mass of the
universe is such that it would form a black hole with an event horizon of radius 15 billion ly. I checked their calculation and it was correct. So in
the past when the observable universe was smaller it could have formed a black hole but what happened to the singularity?
Apparently a flat universe has a total mass/energy of zero. Meaning the mass/energy of its contents is and was balanced by the negative energy of its
gravitational energy. So the universe is not a black hole and even when it was much much smaller it was not a black hole.
I think that supports the idea that the expansion of the universe is kinematic (ballistic).
Here is a link to the wiki entry on the zero energy universe:
https://en.wikipedia.org/wiki/Zero-energy_universe#:~:text=T...
So the hypothesis is that the universe is "a large-scale quantum fluctuation of vacuum energy".
[Edited on 10/19/2022 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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wg48temp9
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Early universe shows time dilation
See https://www.scientificamerican.com/article/time-flowed-five-...
The term "time dilation" usually refers to the slowing of moving clocks due to their velocity (relative to the observer) in Special Relativity. This
effect occurs if the clock is moving away from the observer or towards the observer, or even if the velocity is orthogonal to the line of sight of the
observer. It also causes length contraction.
The time dilation increases the observed red shift of objects at cosmological distances.
More later
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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wg48temp9
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Sorry, I will not be finishing my previous post. I have decided to put the whole storey together. When it's finished (several weeks)I will post a link
to it.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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