Universe expansion question

In summary, the universe is assumed to be expanding because of observations of the space between our galaxy and distant galaxies. This is supported by General Relativity and the discovery of Hubble's Law, which shows a linear relationship between the distance to a galaxy and the redshift of its light. This suggests that space itself is expanding, not just the movement of galaxies in one direction.
  • #1
Tyah
2
0
Why assume that the universe is expanding by observing that the space between our galaxy and distant galaxies is expanding. For example, what if our galaxy and distant galaxies are moving in the same direction, but our galaxy is moving faster than the distant galaxies we have observed. Resulting in the distance between to grow.

I have been thinking about this for some time. Please reply.
 
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  • #2
Okay. According to this theory, in one direction, we'll be, um, moving faster (I suggest you look into a layman's understanding of Special Relativity to understand why this has no meaning :wink: ), and the galaxies will appear to be moving away from us.

But in the other direction, according to your theory, shouldn't galaxies be slowly moving towards us on average?

General Relativity alone is enough evidence for the expansion of the Universe, the observation that faraway galaxies are moving away from us just supports the theory.
 
  • #3
Tyah, welcome to the forum!

Like Whovian said, the expansion is uniform in all directions. This was discovered by Edwin Hubble, using the redshift of light from distant galaxies. When he took a measure of the redshift of this light, he discovered Hubble's Law - that there is a linear relationship between the distance to a galaxy, and the redshift of its light. This is implies that space is expanding - distant photons traverse larger amounts of expanding space.
 
  • #4
thank you. Your replies have been very helpful
 
  • #5


I understand your curiosity and questioning of the assumption that the universe is expanding. It is important to always approach scientific theories and observations with a critical mindset. However, there is a significant amount of evidence and data that supports the theory of the expanding universe.

Firstly, the concept of the universe expanding is not based solely on the observation of the space between our galaxy and distant galaxies. It is also supported by other observations such as the cosmic microwave background radiation, the redshift of distant galaxies, and the distribution of galaxies across the universe.

Additionally, the idea that our galaxy and distant galaxies are moving in the same direction and our galaxy is moving faster is not a plausible explanation for the observed expansion. This would require a perfectly synchronized motion of all galaxies, which is highly unlikely. Furthermore, if this were the case, we would expect to see a homogeneous distribution of galaxies in all directions, which is not what we observe.

Furthermore, the expansion of the universe is not limited to just the space between galaxies. It is also observed in the expansion of space itself, as seen in the stretching of light from distant objects. This is known as the cosmological redshift and is a result of the expansion of space.

Overall, while it is important to question and examine scientific theories, the evidence for the expanding universe is overwhelming. It is the most widely accepted explanation for many observed phenomena in the universe and has been extensively studied and supported by various scientific disciplines. I hope this helps to clarify any confusion and I am happy to continue this discussion.
 

1. What is universe expansion?

Universe expansion refers to the theory that the universe is constantly growing and stretching outwards. This means that the galaxies, stars, and other celestial bodies are moving away from each other.

2. How do we know that the universe is expanding?

Scientists have observed the redshift of light from distant galaxies, which indicates that they are moving away from us. Additionally, the cosmic microwave background radiation, which is leftover from the Big Bang, also supports the theory of universe expansion.

3. What is the rate of universe expansion?

The current estimated rate of universe expansion is 73.3 kilometers per second per megaparsec. This means that for every 3.3 million light-years, the universe expands by 73.3 kilometers per second.

4. Will the universe ever stop expanding?

It is currently unknown if the universe will ever stop expanding. The rate of expansion may change in the future, depending on the amount of dark energy in the universe. It is also possible that the universe may eventually reach a point where it stops expanding and begins to contract.

5. How does universe expansion affect our understanding of the universe?

Universe expansion has greatly impacted our understanding of the universe, as it provides evidence for the Big Bang theory and the age of the universe. It also raises questions about the ultimate fate of the universe and the existence of dark energy. Further research and observation of universe expansion can lead to a deeper understanding of the universe and its origins.

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