Time & Space Expansion: What Does It Mean?

In summary, physicists have proposed the idea that space is expanding, based on a specific way of dividing spacetime into space and time. However, this does not necessarily mean that time is also expanding. The conventional view is that space expands with time, but there are other ways of dividing spacetime where this is not the case. Ultimately, the correctness of this theory is still being debated, with some questioning the validity of Einstein's theory of gravity.
  • #1
earamsey
38
0
Physicists say that space is expanding. Well, Einstein says that space and time can not be separated so I can assume that timespace is expanding. What does it mean for time to expand?
 
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  • #2
"Space is expanding" depends on a particular separation of spacetime into space and time - quite contrary to the spirit of spacetime - spacetime can be separated into space and time many other ways, and in some of those ways, space is not expanding. Anyway, the particular separation of spacetime into space and time used in "space is expanding" is convenient and conventional.
 
  • #3
pardon my ignorance, but what is the answer? I asked question because I keep hearing theory of expanding space and some how it start to not sound correct when one thinks about spacetime. I guess I should not worry about this since I saw a lecture about dark energy that questions the correctness of GR and gravity anyways so maybe I have to wait and see what is the final consensus about it.
 
  • #4
First divide spacetime into space and time - there are many ways to do it - but by convention we choose a way in which space is expanding with time. Since we already chose a division of spacetime into space and time, that space is expanding does not imply that time is expanding.
 

1. What is time and space expansion?

Time and space expansion refers to the idea that the universe is constantly expanding, both in terms of the physical distance between objects and the passage of time. This expansion was first observed by astronomer Edwin Hubble in the 1920s and has since been confirmed by numerous studies and experiments.

2. How does time and space expansion occur?

According to the widely accepted theory of cosmological expansion, the universe is expanding due to the force of dark energy, a mysterious form of energy that makes up about 70% of the universe. As the universe expands, objects within it, such as galaxies and stars, are carried along with it, causing the distance between them to increase.

3. What does time and space expansion mean for the future of the universe?

Based on current scientific understanding, it is believed that time and space expansion will continue indefinitely, with the universe becoming increasingly larger and more spread out. Eventually, this expansion may lead to the "heat death" of the universe, where all matter and energy is spread out and can no longer sustain life or any other processes.

4. Is there any evidence for time and space expansion?

Yes, there is strong evidence for time and space expansion. One of the main pieces of evidence is the observed redshift of light from distant galaxies, which indicates that they are moving away from us and supports the idea of an expanding universe. Additionally, the cosmic microwave background radiation, a remnant of the Big Bang, also provides evidence for time and space expansion.

5. How does time and space expansion relate to the Big Bang theory?

The Big Bang theory, which is the prevailing scientific explanation for the origin of the universe, is closely tied to the concept of time and space expansion. According to the Big Bang theory, the universe began as a single point of infinite density and has been expanding ever since. This expansion is what has led to the formation of galaxies, stars, and other structures in the universe.

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