Why Does the Expanding Universe Cause Red Shift?

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Discussion Overview

The discussion revolves around the concept of the expanding universe and its relation to red shift. Participants explore the mechanisms behind the expansion, the nature of space, and the implications for observed phenomena such as red shift, acceleration of distant objects, and the role of dark energy.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that the universe is expanding, which accounts for red shift as objects accelerate away from each other.
  • Others propose that it is the space itself that is expanding, leading to questions about the constancy of distances between objects and the implications for red shift.
  • One participant expresses confusion about the acceleration of objects and questions the existence of a constant force causing this acceleration, suggesting a lack of clarity on the underlying mechanisms.
  • Another participant mentions dark energy as a possible explanation for the acceleration of expansion, noting that its true nature remains unknown.
  • A different viewpoint introduces the idea that energy loss of photons, potentially due to a super-massive black hole, could explain red shift, challenging the conventional understanding.
  • There is mention of "Tired Light" models being discussed as inadequate explanations for red shift, indicating ongoing debate about alternative theories.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of the universe's expansion and its implications for red shift, with no consensus reached on the mechanisms involved or the validity of competing models.

Contextual Notes

Participants highlight the complexity of the topic, including the unresolved nature of dark energy and the challenges in understanding the acceleration of the universe's expansion. There are references to ongoing research and the limitations of current models.

Who May Find This Useful

This discussion may be of interest to those exploring cosmology, the nature of the universe, and the implications of red shift in astrophysics.

ChrisXenon
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We hear that the universe is expanding, and this accounts for red shift as all objecsts are accellerating away from each other.

But I have also heard that it is the space itself, of which the universe made, that is expanding - not that things are moving in that space.
If so, then the distances between objects as measured in this expanding space is presumably constant, since the "rulers" would also be expanding in that same space.
And in this case, there would be no red shift.
Clearly, I'm wrong, and I'm hoping someone can straighten my out on this.

This might relate to another puzzle I have.
I am told not only that things are moving away from each other, but that things are accelerating away from each other.
Since these objects are isolated, what is the constant force which is causing this acceleration?
Or, if we are way beyong Newton at this point, how is this accelleration caused?

Thanks again, Chris
 
Astronomy news on Phys.org
Rulers are not expanding.

The acceleration of expansion (discovered about ten years ago) is due to something given the name "dark energy". No one knows what it really is, although it seems to be related to the "Cosmological Constant" in general relativity.
 
The Perlmutter study injected dark energy into the mix. See
http://physicsworld.com/cws/article/print/31910
 
ChrisXenon said:
We hear that the universe is expanding, and this accounts for red shift as all objecsts are accellerating away from each other.

But I have also heard that it is the space itself, of which the universe made, that is expanding - not that things are moving in that space.
If so, then the distances between objects as measured in this expanding space is presumably constant, since the "rulers" would also be expanding in that same space.
And in this case, there would be no red shift.
Clearly, I'm wrong, and I'm hoping someone can straighten my out on this.

Bound systems - held together by gravity or electromagnetic forces - can oppose the expansion so they don't change. At least for now.

This might relate to another puzzle I have.
I am told not only that things are moving away from each other, but that things are accelerating away from each other.
Since these objects are isolated, what is the constant force which is causing this acceleration?
Or, if we are way beyong Newton at this point, how is this accelleration caused?

Thanks again, Chris

Newton still holds, but we presently don't know what is causing the observed acceleration. There are lots of theories, but no definite answers as yet. That's why we're still making bigger and better telescopes to study it further. If we knew why, then the need for the scopes would be less.

Beware of physicists with too many answers. They might be trying to sell you something ;-)
 
universe is expanding. maybe not! think if the photons ,we see in Hables telescope, are with more or less energy they change colors spectre - so if in middle of universe is huge super-massive black hole , which evidence universe , then on its way photon loose energy and we see it as red or violet or blue..
 
uh thanks! that's help a lot...
anyway - do we have thread - how universe is made?

btw it was idea i made myself - that i liked ;(
 
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