Expanding Universe and the Red Shift

PixyMisa said:
That's what I think Mel is saying, yeah.
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Every thread I've read that Melendwyr's participated in has included a lot of terminology used in unorthodox ways, often resulting in a degradation into debates over semantics. The sad thing is, some of the ideas might be worth considering if presented in a less arrogant way and without confusing things by misusing established terminology.
 
If I understand Melendwyr's theory correctly it's that space itself is expanding, ie, there is new space appearing all the time. However, if this were true then the same should be happening between the stars within our own Galaxy, implying that we should see a redshift increase as we look at more distant stars in the Milky Way. What we actually see is nothing of the kind, we just see orbital rotation with no apparent expansion of the Galaxy.

So, Melendwyr, please explain how the space between galaxies is expanding, but not the space within our own Galaxy.
 
wollery said:
If I understand Melendwyr's theory correctly it's that space itself is expanding, ie, there is new space appearing all the time. However, if this were true then the same should be happening between the stars within our own Galaxy, implying that we should see a redshift increase as we look at more distant stars in the Milky Way. What we actually see is nothing of the kind, we just see orbital rotation with no apparent expansion of the Galaxy.

So, Melendwyr, please explain how the space between galaxies is expanding, but not the space within our own Galaxy.
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It is expanding within our own galaxy. But the distances between the galaxies is so much bigger than the diameter of any single galaxy, that means that we see the effect much better. It acumulates over distance, the bigger the distance, the bigger the expansion.
 
TobiasTheCommie said:
It is expanding within our own galaxy. But the distances between the galaxies is so much bigger than the diameter of any single galaxy, that means that we see the effect much better. It acumulates over distance, the bigger the distance, the bigger the expansion.
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Ho is ~ 70km/s/Mpc or ~70m/s/kpc. 70m/s is measurable for stars, and 1kpc is about the scale height of the thick disk.

Even if nobody has yet looked for this effect it won't be long before the data is available to do it.
 
chipmunk stew said:
Every thread I've read that Melendwyr's participated in has included a lot of terminology used in unorthodox ways, often resulting in a degradation into debates over semantics.
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If the established terminology would permit accurate description of the concepts involved, I'd use it.

The sad thing is that too many people are unable to interpret what's written, instead of what they expect to see written. Also, that so many view someone who is right and doesn't yield when he's right as "arrogant".

To return to the thread topic: the Big Bang isn't "my" hypothesis, and I have no desire or duty to defend it.
 
Wait. I thought it space that was expanding. That's why they always say that it wasn't just matter, but also space-time that was compressed in the big-bang. And the old point that the universe didn't expand into anything.

On the other hand, I don't see why something carried along by expanding space-time wouldn't be said to be moving. Mel, I think that's why others are disagreeing with you.

Maybe everyone is just talking across each other. It'd be nice for people to try to say what they think is different about what they are saying from those they disagree with, because I'm not sure I see it.
 
wollery said:
Ho is ~ 70km/s/Mpc or ~70m/s/kpc. 70m/s is measurable for stars, and 1kpc is about the scale height of the thick disk.

Even if nobody has yet looked for this effect it won't be long before the data is available to do it.
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i'm not sure if your numbers are correct, nor do i know if 70m/s can be measured, even on stars in our own galaxy.

But, if you say so, i will bow to your better judgement, that is, untill someone gives contradicting information.
 
Roboramma said:
On the other hand, I don't see why something carried along by expanding space-time wouldn't be said to be moving. Mel, I think that's why others are disagreeing with you.
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What speed do you walk at, lets say 6km/h.

So, if the limit on the speed you can move with, is 6km/h, and for light that is c, then what if you are in a train that moves at 60km/h, you will still only be moving at 6km/h compared to your surroundings(the train), but for an observer outside the train you will be moving at 66km/h.

The same goes for light, light can only move at c, but if the space/time the light is moving is moving at ½c(to an outside observer), the light will appear to be moving at 1½c, though for the light itself it will only be moving 1c compared to the space/time around it.

afaik there is no limit to the speed at which space/time can move or expand, not even the speed of light.

Sincerely
Tobias
 
TobiasTheCommie said:
i'm not sure if your numbers are correct, nor do i know if 70m/s can be measured, even on stars in our own galaxy.

But, if you say so, i will bow to your better judgement, that is, untill someone gives contradicting information.
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Planet Search measure relative velocity to about +/-4m/s.
 
wollery said:
ie, there is new space appearing all the time. However, if this were true then the same should be happening between the stars within our own Galaxy, implying that we should see a redshift increase as we look at more distant stars in the Milky Way.
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Space is expanding everywhere, even in our own galaxy. However, the stars here are gravitationally bound so are at equilibrium with the expanding space.

Space is expanding inside your own body too, but the forces that hold atoms to each other make them remain close.
 
Roboramma said:
On the other hand, I don't see why something carried along by expanding space-time wouldn't be said to be moving. Mel, I think that's why others are disagreeing with you.

Maybe everyone is just talking across each other. It'd be nice for people to try to say what they think is different about what they are saying from those they disagree with, because I'm not sure I see it.
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Nothing can move *though* space faster than the speed of light. That's precisely why we can never see anything falling into a black hole past the event horizon - from our perspective, everything gets closer and closer without ever reaching it, because light at the event horizon cannot escape, and time (from our perspective) is so distorted that the information of the object transiting the horizon never arrives. From an external point of view, the object only actually reaches the singularity at the moment the singularity evaporates.

If we claim that distant objects are actually *moving*, then as they get farther away, they'll get faster and faster - eventually they will reach the point where we can no longer see them, as they're traveling away at the speed of light. That is, however, impossible.

If we claim that objects are being separated by expanding space, the distance between them and us *can* be increasing faster than light can travel to us, without anything actually moving.

You can choose a reference frame in which everything's moving, just as you can choose a reference frame in which the Earth stays still while everything orbits around it. But that's messed up, so we say the Earth orbits the Sun. Same deal: the 'tricks' necessary to make the objects moving are so weird that we say they're stationary and space expands instead.
 
CurtC said:
Space is expanding everywhere, even in our own galaxy. However, the stars here are gravitationally bound so are at equilibrium with the expanding space.
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It would be somewhat more accurate to say that they're at equilibrium, which incorporates both the inward draw of gravity, their angular momentum, AND the outward push of expansion.
 
Melendwyr said:
If we claim that distant objects are actually *moving*, then as they get farther away, they'll get faster and faster - eventually they will reach the point where we can no longer see them, as they're traveling away at the speed of light. That is, however, impossible.
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OK, I've had a good night's sleep and a good meal, so I'm going to take a shot at this. SpaceFluffer, you're the expert here so feel free to jump in and correct me if I screw this up.

I think the problem here is you're treating the Earth as if it's a privileged point of reference. The Hubble constant says things move away from us faster the farther they are away, and at one point they're far enough away that the recession speed equals c and we can no longer see them.

However, if we could move to a vantage point halfway between Earth and whatever an Earthbound observer sees receding at c, we'd see that object in one direction and the Earth in the opposite direction both receding away from us at 1/2 c .

It's the balloon analogy all over again: If you paint a bunch of spots on the surface of a balloon and blow it up, the spots all move away from each other. But if you were standing on one spot it would look like you were standing still and all the other spots were moving away from you. There is no absolute speed on this scale - how fast the object is moving depends on where you've viewing it.

Well, that's about as good an explanation as I can give. Those wishing to poke holes may fire when ready.

:boxedin:
 
The Hubble Constant establishes a link between distance and redshift. "Movement" is inferred from the redshift. However, the simplest way to understand the explanation for Hubble's constant is NOT to say that everything else is moving.

Saying that the Earth orbits the Sun also presumes a priviledged reference frame. Nevertheless, how would you respond to someone who challenged that statement publically?
 
Melendwyr said:
The Hubble Constant establishes a link between distance and redshift. "Movement" is inferred from the redshift. However, the simplest way to understand the explanation for Hubble's constant is NOT to say that everything else is moving.
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So it is your contention that our solar system is at the center of the Universe and everything else is moving away from us?

Melendwyr said:
Saying that the Earth orbits the Sun also presumes a priviledged reference frame. Nevertheless, how would you respond to someone who challenged that statement publically?
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I would challenge them to come up with a reference frame in which the Earth does not orbit the Sun. If they can't, then there is no "privileged reference frame". I would also mention the fact that Einstein's theory of relativity says that there are no privileged reference frames, so if you want to say there are you'll need to show me exactly where Einstein went wrong.
 
Genesius said:
So it is your contention that our solar system is at the center of the Universe and everything else is moving away from us?
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I think that's a perfectly valid thing to say. At least, our galaxy is at the center and every other galaxy is moving away from us. Of course, every galaxy could consider itself the center and they all would be right.

But that's not the point that Mel was making. Mel is saying that it's simpler *not* to think of the other galaxies as moving away from us, but instead it's simpler to think of them all as standing still, but the space between them is expanding. And that's valid.
 
CurtC said:
Mel is saying that it's simpler *not* to think of the other galaxies as moving away from us, but instead it's simpler to think of them all as standing still, but the space between them is expanding.
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Is this just a matter of what words we use to describe the situation, or are the two situations really different somehow?

Suppose I and some nearby object are "really moving" away from each other at 1 m/s. Now suppose that we aren't "really moving", but that "the space between us is expanding" in such a way that the distance between us is increasing at 1 m/s. Do I notice anything different? If so, what?
 
Thanks to you all for the replies, comments, advice and debate on my thread. Obviously a controversial subject. My original post was poorly written so thought I would rewrite it to hopefully clarify what I meant. I’m very happy with what I have gained from the first post so there is no need to reply to this unless you have something new to offer. I’m simply trying to explain my thoughts better . . .


The Big Bang Theory is vindicated by the Expanding Universe Theory, which in turn is vindicated by the Red Shift Theory. Being a devout sceptic, I’m compelled to test the veracity of these theories (in my own mind), regardless of the rigorous checks and balances that I’m aware exist in science. The Red Shift Theory was formulated to explain why immensely distance stars appear red in colour. The purpose of my original post was to “brain storm” other possible (or impossible) explanations. I’m happy with the Expanding Universe Theory/Doppler Effect to explain a Red Shift.
The three alternative suggestions I offered were . . .

Cosmic Sunset - Perhaps there is something (anything - I don‘t know what - maybe something as yet undiscovered) in space that has an effect on light as it travels from distance stars and causes them to appear red in colour. I didn‘t mean to suggest that this was in any way the same as what causes a sunset on Earth.

Degraded Light - Time and distance seem to degrade most things, so I thought - why not light? It was interesting to discover Tired Light and Photon Decay already exist as theories.

Multi-Speed Light - Perhaps red photons travel faster than other photons so that light that has travelled over an immense distance would contain a higher percentage red photons making it appear more red in colour.

Hope it makes more sense now (but perhaps not more sensible)
 
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