A Problem with (Almost) Universal Red Shift

In summary, the conversation discusses the concept of the expanding universe and how everything in the universe, except for a few local galaxies, is moving away from each other. The question is raised about how a large collection of randomly placed objects can all be moving away from each other, and the explanation is given that this is due to the expansion of spacetime between these objects. It is also mentioned that while distant galaxies may have some random motion, it is insignificant compared to the overall expansion of the universe. This concept forms the basis of the expanding universe theory.
  • #1
jaston
3
0
It is my understanding that, except for a couple of local galaxies, everything in the universe is moving away from us as well as from each other (relationships between inhabitants of local galactic groups excepted). If my information is acurate, how is it that a large collection of randomly placed objects could possibly act in that way? Wouldn't some of them have to be moving toward us?

I ask because the only way that makes sense to me is if all super massive objects/groups in the universe are actually motionless and the spacetime between them is expanding. Any motion at all from them would, in some direction, be read as a blue shift and just by the strength of numbers, some of those blue shifts would be pointing in our direction.
 
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  • #2
I believe (not really sure) that distant galaxies DO have a local motion that is random relative to their direction to earth, BUT this motion is utterly trivial relative to the "motion" we see due to expansion.
 
  • #3
Sure, there are variations where some have more motion towards us than others do, but as you get further and further away the average redshift steadily increases.
 
  • #4
No mystery here. This is the foundation for the expanding universe idea.
 
  • #5


Thank you for your question. The concept of universal red shift is a well-established phenomenon in astrophysics, and it is supported by extensive observational evidence. However, I understand your confusion about the apparent contradiction between everything in the universe moving away from us and some objects possibly moving towards us.

Firstly, it is important to clarify that the universal red shift is not caused by the motion of objects in the universe. Instead, it is a result of the expansion of the universe itself. The expansion of the universe causes the wavelength of light from distant objects to stretch, resulting in a red shift. This is similar to the Doppler effect, where the wavelength of sound waves appears to change as an object moves towards or away from us. In the case of the universe, the expansion of space itself is causing the red shift, not the motion of objects within it.

Secondly, while it may seem counterintuitive, it is possible for all objects in the universe to be moving away from each other. This is because the expansion of the universe is happening on a large scale, at the level of the entire universe. On smaller scales, such as within galaxies or galactic groups, the gravitational forces are strong enough to counteract the expansion and keep objects in relatively close proximity to each other. However, on a larger scale, the expansion of space becomes the dominant force and causes everything to move away from each other.

In summary, the universal red shift is a result of the expansion of the universe, not the motion of objects within it. And while it may seem counterintuitive, it is possible for all objects in the universe to be moving away from each other due to the effects of the expansion of space on a large scale. I hope this explanation helps clarify any confusion you may have had.
 

1. What is the problem with the universal red shift theory?

The problem with the universal red shift theory is that it suggests that all galaxies are moving away from each other at an accelerating rate, which contradicts the basic principles of gravity and the laws of motion.

2. How does the universal red shift theory impact our understanding of the universe?

The universal red shift theory calls into question our understanding of the expansion of the universe and the role of dark energy in this expansion. It also challenges our current understanding of the age and size of the universe.

3. What evidence supports the universal red shift theory?

The main evidence for the universal red shift theory comes from observations of the redshift of light from distant galaxies, which suggests that they are moving away from us at increasing speeds. Additionally, the cosmic microwave background radiation also supports this theory.

4. Are there any alternative explanations for the red shift phenomenon?

Yes, there are alternative explanations for the red shift phenomenon, such as the tired light theory, which proposes that the red shift is caused by the interaction of light with matter as it travels through space.

5. What further research is needed to better understand the red shift phenomenon?

Further research is needed to gather more precise and accurate measurements of the red shift in different areas of the universe. This can help us better understand the rate of expansion and determine if there are any discrepancies or anomalies that could challenge the universal red shift theory.

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