The Universe does NOT, and thus is NOT, 'expanding'. Therefore, the rest is moot.
Dark Energy, Dark Matter
Re: Dark Energy, Dark Matter
Re: Dark Energy, Dark Matter
More funnier I find here is that it is being CLAIMED that the further we look back, 'expansion' was slower, or decelerating, and the closer we look back 'expansion' is faster, more dominant, or more powerful. YET, the further we look back, the more things are redshifted on the spectrum and the closer we look back the more blueshift there is on the spectrum. Which completely CONTRADICTS what has been previously CLAIMED.Cerveny wrote: ↑Thu Jul 07, 2022 9:53 am Funny enough, we don't know what physical space is, but we do know what a "black hole" is:)
viewtopic.php?p=488112#p488112
But maybe all of this can be explained away. We will wait to see.
Re: Dark Energy, Dark Matter
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Re: Dark Energy, Dark Matter
I thought the speed of galaxies depended on the galactic clutch...
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Re: Dark Energy, Dark Matter
When objects move relationally due to the Hubble flow (the expansion), it isn't kinetic, isn't a proper acceleration. We call the actual motion of galaxies peculiar motion, and it generally has an upper cap (~2000 km/s). A lot of people mistakenly think that the redshifting from cosmic expansion is a Doppler effect, but that's not correct: there is a Doppler effect from the peculiar motion of galaxies, but it is dominated by the Hubble flow above a certain distance away (because the apparent motion due to space expanding will vastly outstrip the <2000 km/s peculiar motion until the peculiar motion is negligible).
We can see that here:
In a perfect universe with no peculiar motion (where all motion is just from space expanding), galaxies would move apart with the Hubble flow (represented by the blue line) and all of them would be redshifted, even our closest neighbors. However, galaxies obey gravity, so they're all moving around (peculiar motion), and some of them overpower the expansion thanks to gravity (the ones below zero on the y-axis are blueshifted).
The ones in the blue oval are just smattered all over the place because they're part of the Virgo supercluster: more mass, more gravity, more peculiar motion (which causes them to deviate from the Hubble flow by redshifting more than they otherwise would or less than they otherwise would: technically a "blueshift" from the Hubble flow, but to us we still see a net redshift).
Zoom out to see greater distances and all you see is redshift because the Hubble flow dominates peculiar motion:
Nothing but redshifting here, which gets worse and worse and worse.
This is one of the main reasons that redshifting is interpreted as an expansion rather than as some alternative idea, like "tired light."
Tl;dr, the Hubble flow isn't kinetic motion so it doesn't take energy to "accelerate" galaxies as it's not an acceleration. Peculiar motion is kinetic, but it also obeys well-known kinematics.
Re: Dark Energy, Dark Matter
How does one qualify as a proper acceleration?
Why wouldn't Hubble flow create a Doppler effect?
Re: Dark Energy, Dark Matter
Proper acceleration is a measurable acceleration experienced by an object. Galaxies don't experience an acceleration from the Hubble flow though: they are at rest with respect to the CMB (cosmic microwave background radiation). It's the space itself that's expanding, not that the galaxies are "moving." Since space expands, we see it as if it were moving -- and accelerating. But it's not what's called a proper acceleration. So it's not kinetic.
The same is true for the Doppler effect, you need proper motion for it to properly be called the Doppler effect -- like when an ambulance passes you and the pitch changes. This is true for the redshifting and blueshifting of galaxies from their peculiar motion (which is a proper motion), but their apparent motion from the expansion/Hubble flow isn't. The reason the light redshifts is literally because the space it occupies as it travels expands, increasing the wavelength.
Edit: I said "galaxies are at rest with respect to the CMB" and I need to clarify. They are mostly at rest with respect to it, they still have their peculiar motion. We see a dipole in the CMB because of our motion relative to it.
Re: Dark Energy, Dark Matter
Ah, of course! Now I get it. Thanks for that.
I get that too, but isn't it just a case of definition? Whatever the cause of relative motion, is it not so that the distance between red shifted galaxies is increasing?
Yeah, I get that. What effect does it have on amplitude?
Sorry, dunno what you mean by dipole in this context, so your point has gone completely over my head.
Anyway; off to the pub to catch up with an old mate. I leant him my telescope a few weeks back. Pretty certain he hasn't used the bloody thing.
Re: Dark Energy, Dark Matter
Waiting on my hair to dry so I can put my face on, heading on vacay soon. So sorry if this is short for now!uwot wrote: ↑Fri Jul 08, 2022 12:50 pmAh, of course! Now I get it. Thanks for that.I get that too, but isn't it just a case of definition? Whatever the cause of relative motion, is it not so that the distance between red shifted galaxies is increasing?Yeah, I get that. What effect does it have on amplitude?Sorry, dunno what you mean by dipole in this context, so your point has gone completely over my head.
Anyway; off to the pub to catch up with an old mate. I leant him my telescope a few weeks back. Pretty certain he hasn't used the bloody thing.
Yes it’s just a matter of definition, though I can maybe see why there’s a difference in redshift being caused by emission while moving and redshift caused *after* emission, while in transit, because the space itself between hills and troughs increases over the journey.
Like if light were on a rubber band as a squiggle and you had miraculously fast hands to stretch the band after emission, you’d redshift it.
The CMB dipole (can google images that phrase to see it) is a red/blue swirl when some of the noise is cut out of the CMB and it’s because we’re moving with respect to it.
Re: Dark Energy, Dark Matter
A lot of people also mistakenly think, and some even BELIEVE, that the Universe is expanding, but that is NOT correct: there 'is' an expansion effect from a 'bang', which is what dominated this expansion. The rate of expansion, and contraction, however, varies WIDELY, depending on where matter is 'sitting', or is 'placed', in relation to 'itself', and how long the length after that 'bang' occurred.Astro Cat wrote: ↑Fri Jul 08, 2022 8:42 amWhen objects move relationally due to the Hubble flow (the expansion), it isn't kinetic, isn't a proper acceleration. We call the actual motion of galaxies peculiar motion, and it generally has an upper cap (~2000 km/s). A lot of people mistakenly think that the redshifting from cosmic expansion is a Doppler effect, but that's not correct: there is a Doppler effect from the peculiar motion of galaxies, but it is dominated by the Hubble flow above a certain distance away (because the apparent motion due to space expanding will vastly outstrip the <2000 km/s peculiar motion until the peculiar motion is negligible).
We can see that here:
We can see, and observe, this everywhere.
ALL matter 'obeys' contraction, [gravity], AND expansion. As already partly explained whether matter is 'expanding' or 'contracting' is all depended on the 'observer'. As absolutely EVERY 'thing' is 'relative', to the 'observer'.Astro Cat wrote: ↑Fri Jul 08, 2022 8:42 am
In a perfect universe with no peculiar motion (where all motion is just from space expanding), galaxies would move apart with the Hubble flow (represented by the blue line) and all of them would be redshifted, even our closest neighbors. However, galaxies obey gravity, so they're all moving around (peculiar motion), and some of them overpower the expansion thanks to gravity (the ones below zero on the y-axis are blueshifted).
'Peculiar', like the 'complex' word, is just another word used instead of the ACTUAL Truth, which is; "We do not yet know what is actually occurring".Astro Cat wrote: ↑Fri Jul 08, 2022 8:42 am The ones in the blue oval are just smattered all over the place because they're part of the Virgo supercluster: more mass, more gravity, more peculiar motion (which causes them to deviate from the Hubble flow by redshifting more than they otherwise would or less than they otherwise would: technically a "blueshift" from the Hubble flow, but to us we still see a net redshift).
What ACTUAL occurs is VERY SIMPLE and EXTREMELY EASY to UNDERSTAND and KNOW.
As I have been continually SAYING and POINTING OUT in this forum the 'redshift data' gets MISINTERPRETED BECAUSE of people's underlying BELIEFS and ASSUMPTIONS.Astro Cat wrote: ↑Fri Jul 08, 2022 8:42 am Zoom out to see greater distances and all you see is redshift because the Hubble flow dominates peculiar motion:
Nothing but redshifting here, which gets worse and worse and worse.
This is one of the main reasons that redshifting is interpreted as an expansion rather than as some alternative idea, like "tired light."
Which is the EXACT SAME reason WHY "astro cat's", and "other physicists" INTERPRETATIONS of 'the data' is ALSO Wrong AND Incorrect.
Re: Dark Energy, Dark Matter
And the word 'space', in relation to the Universe, is JUST the 'distance' between and/or around 'matter', as I have been saying all along here.Astro Cat wrote: ↑Fri Jul 08, 2022 12:16 pmProper acceleration is a measurable acceleration experienced by an object. Galaxies don't experience an acceleration from the Hubble flow though: they are at rest with respect to the CMB (cosmic microwave background radiation). It's the space itself that's expanding, not that the galaxies are "moving."
So, what this means is that when "physicists", or "others", say that 'it is space itself that is expanding', what this ACTUALLY refers to is that 'just the distance between 'matter' is getting longer, or 'expanding'. All VERY SIMPLE, REALLY.
If one sees/observes 'expanding', then they do NOT necessarily SEE this as though there is some 'thing' itself is 'moving', other than the length, or the distance, between 'matter' is what is 'moving', in the sense of the 'distance'' is just getting longer (expanding), or shorter (contracting'. And, because absolutely EVERY thing is 'relative to the observer', what one SEES is NOT necessarily what another one SEES.
Also, when one SEES 'space', or the 'distance', 'moving', there is NO compulsory reason that they also SEE 'acceleration' AT ALL. So, what this means is, since space/distance 'expands', (as well as 'contracts' by the way), if 'you' see it as 'if' space were moving -- AND 'accelerating', then that maybe what 'you' SEE, but 'accelerating' does NOT have to be involved NOR included. But, as 'you' said here, 'space', which is just 'distance' is ALWAYS 'moving', and CHANGING, and this is because 'matter' is ALWAYS 'moving', and thus CHANGING 'position', within the Universe.
'Proper' motion in relation to 'what' EXACTLY, 'improper' motion?
If yes, then what is 'improper' motion, EXACTLY?
But if no, then 'what', EXACTLY, is 'proper' motion in relation to?
I suggest when people say or write, "This is true", like when they say or write, "This is the true story", and this is heard or seen, then one just become more AWARE of the thoughts within, and notice if those 'triggers' words are setting them up somehow.Astro Cat wrote: ↑Fri Jul 08, 2022 8:42 am This is true for the redshifting and blueshifting of galaxies from their peculiar motion (which is a proper motion), but their apparent motion from the expansion/Hubble flow isn't. The reason the light redshifts is literally because the space it occupies as it travels expands, increasing the wavelength.
What ALL of these VASTLY DIFFERENT, and continually CHANGING, INTERPRETATIONS, which are just GUESSES of what MIGHT BE OCCURRING or OF MIGHT HAVE OCCURRED, are consistent with 'confirmation biasing'. And the Fact that all of these VARYING INTERPRETATIONS are coming from those who ASSUME or BELIEVE that there WAS A BEGINNING, EXPLAINS WHY these INTERPRETATION, THEORIES, and ASSUMPTIONS are CONTINUALLY CHANGING.
Re: Dark Energy, Dark Matter
So, it is, "just a matter of definition", when regarding these 'things', but when it comes down to the definition of the word 'Universe', which, literally, absolutely EVERY thing ELSE revolves around, then you are NOT 'very interested' in 'that'.Astro Cat wrote: ↑Fri Jul 08, 2022 1:29 pmWaiting on my hair to dry so I can put my face on, heading on vacay soon. So sorry if this is short for now!uwot wrote: ↑Fri Jul 08, 2022 12:50 pmAh, of course! Now I get it. Thanks for that.I get that too, but isn't it just a case of definition? Whatever the cause of relative motion, is it not so that the distance between red shifted galaxies is increasing?Yeah, I get that. What effect does it have on amplitude?Sorry, dunno what you mean by dipole in this context, so your point has gone completely over my head.
Anyway; off to the pub to catch up with an old mate. I leant him my telescope a few weeks back. Pretty certain he hasn't used the bloody thing.
Yes it’s just a matter of definition,
The MAIN reason WHY 'you', human beings, back in the days when this was being written, were STILL SO LOST and CONFUSED in regards to what the 'Universe' is ACTUALLY 'made up' of, how the 'Universe' ACTUALLY 'works', and IF the 'Universe' ACTUALLY 'began' and/or 'is expanding' or NOT is BECAUSE of the DIFFERENT definitions you ALL USED for the EXACT SAME word 'Universe'. I suggest you just START there, AND THEN you move on, and along.
The EXACT SAME 'phenomena' EXISTS. 'you' ALL just SEE and OBSERVE 'It' DIFFERENTLY, because of your OWN 'biases', which are based upon your OWN ASSUMPTIONS and BELIEFS.
Rid "yourselves" of those ASSUMPTIONS and BELIEFS, then what is ACTUALLY and IRREFUTABLY True and Right becomes BLINDLINGLY OBVIOUS and CRYSTAL CLEAR.
Is there ANY 'thing' NOT 'moving', with respect to 'it'?Astro Cat wrote: ↑Fri Jul 08, 2022 1:29 pm though I can maybe see why there’s a difference in redshift being caused by emission while moving and redshift caused *after* emission, while in transit, because the space itself between hills and troughs increases over the journey.
Like if light were on a rubber band as a squiggle and you had miraculously fast hands to stretch the band after emission, you’d redshift it.
The CMB dipole (can google images that phrase to see it) is a red/blue swirl when some of the noise is cut out of the CMB and it’s because we’re moving with respect to it.
In fact is there absolutely ANY 'thing', which is NOT 'moving', with respect to ANOTHER 'thing'?
Re: Dark Energy, Dark Matter
Hope you had a lovely time.
Is galactic redshift different to what it would be were space not expanding? I'm not challenging the idea of expanding space, I'm trying to get my head round how red-shift works in practise. I kinda think that intergalactic space behaves as a medium (a lens in effect) with a variable refractive index - I don't imagine that the threshold between gravity and dark energy, while no doubt describable mathematically, is clear in many places in a fuzzy universe. Given that, I don't see why, if a rubber band were stretched by miraculous hands in intergalactic space, it isn't squeezed as it re-enters galactic space. (I now have an image of a cosmic concertina) As I understand, Hubble was able to infer that galaxies were spreading out from redshift without reference to any intergalactic medium.Astro Cat wrote: ↑Fri Jul 08, 2022 1:29 pmYes it’s just a matter of definition, though I can maybe see why there’s a difference in redshift being caused by emission while moving and redshift caused *after* emission, while in transit, because the space itself between hills and troughs increases over the journey.
Like if light were on a rubber band as a squiggle and you had miraculously fast hands to stretch the band after emission, you’d redshift it.
For anyone not sure about the difference, Astro Cat's rubber band and miraculous hand analogy can be contrasted with Doppler Effect red-shift caused by relative motion; an example being that if you run into the sea, the waves will hit you harder and with greater frequency than if you are running out of the sea. Your motion will also change the apparent wavelength. It just happens that to our eyes, waves that hit them more gently appear more red than waves that hit harder.
Re: Dark Energy, Dark Matter
'Redshift' just shows 'matter' moving away from 'the observer'. 'Blueshift' just shows the opposite. Now, because 'objects of matter' move around other 'objects of matter', sometimes objects are coming towards 'us', the observer, and sometimes objects are moving away from 'us', the observer, and the reason WHY there is more 'redshift' is because the further out, spatially, we look, thus the further back, temporally, we are seeing, and closer to 'that bang', generally, but not necessarily correctly, known as 'the big bang', the more 'expansion' was occurring. That is; the more 'matter' was moving away from the point of 'that bang', which was of the 'object of matter' that 'expanded'.uwot wrote: ↑Sun Jul 10, 2022 7:22 amHope you had a lovely time.Is galactic redshift different to what it would be were space not expanding? I'm not challenging the idea of expanding space, I'm trying to get my head round how red-shift works in practise. I kinda think that intergalactic space behaves as a medium (a lens in effect) with a variable refractive index - I don't imagine that the threshold between gravity and dark energy, while no doubt describable mathematically, is clear in many places in a fuzzy universe. Given that, I don't see why, if a rubber band were stretched by miraculous hands in intergalactic space, it isn't squeezed as it re-enters galactic space. (I now have an image of a cosmic concertina) As I understand, Hubble was able to infer that galaxies were spreading out from redshift without reference to any intergalactic medium.Astro Cat wrote: ↑Fri Jul 08, 2022 1:29 pmYes it’s just a matter of definition, though I can maybe see why there’s a difference in redshift being caused by emission while moving and redshift caused *after* emission, while in transit, because the space itself between hills and troughs increases over the journey.
Like if light were on a rubber band as a squiggle and you had miraculously fast hands to stretch the band after emission, you’d redshift it.
For anyone not sure about the difference, Astro Cat's rubber band and miraculous hand analogy can be contrasted with Doppler Effect red-shift caused by relative motion; an example being that if you run into the sea, the waves will hit you harder and with greater frequency than if you are running out of the sea. Your motion will also change the apparent wavelength. It just happens that to our eyes, waves that hit them more gently appear more red than waves that hit harder.
Also, 'dark energy' and 'dark matter' were just terms made up, to somehow "explain" what causes 'expansion'. A bit like how the word 'God' was made up to "explain" 'everything', and that there was 'a beginning'.
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Re: Dark Energy, Dark Matter
I wonder whether we are accelerating at approximately 10m/s/s?Astro Cat wrote: ↑Fri Jul 08, 2022 12:16 pmProper acceleration is a measurable acceleration experienced by an object. Galaxies don't experience an acceleration from the Hubble flow though: they are at rest with respect to the CMB (cosmic microwave background radiation). It's the space itself that's expanding, not that the galaxies are "moving." Since space expands, we see it as if it were moving -- and accelerating. But it's not what's called a proper acceleration. So it's not kinetic.
The same is true for the Doppler effect, you need proper motion for it to properly be called the Doppler effect -- like when an ambulance passes you and the pitch changes. This is true for the redshifting and blueshifting of galaxies from their peculiar motion (which is a proper motion), but their apparent motion from the expansion/Hubble flow isn't. The reason the light redshifts is literally because the space it occupies as it travels expands, increasing the wavelength.
Edit: I said "galaxies are at rest with respect to the CMB" and I need to clarify. They are mostly at rest with respect to it, they still have their peculiar motion. We see a dipole in the CMB because of our motion relative to it.