- #1
ukmicky
- 114
- 1
How do they know the universe is expanding when all the evidence pointing to that fact is millions or even billions of years old.
LURCH said:The best answer is to switch your statement from "millions or billions", to "millions and billions". Truth is, all the evidence we have shows the same story; redshift. We see redshift in objects billions of lightyears away, and in objects just a few million lightyears away. So, if our interprtation of the data (that redshift means expansion) is correct, then we can see that the universe was expanding several billion years ago, that it was still expanding a couple hundred million years ago, and yet still expanding 10 0r 20 million years ago. From this, we can conclude with considerable certainty that this condition still persists (simlpy by assuming that what the whole universe has done for the past several billion years, it did not cease to do just before we looked).
Lunatic said:It's not expanding, the space in between the objects that we can identify is increasing
That's not really the issue though, the point i was trying to to raise is, if the evidence we are relying on is millions AND billions of years out of date how can it be used as evidence for what could be happening to the universe today. a lot of things can happen in a few million years much more in a billion.Lunatic said:It's not expanding, the space in between the objects that we can identify is increasing
ukmicky said:The evidence of expansion is at best millions of years out of date and wouldn't stand up in court.
Scientists have been able to determine that the universe is expanding through various observations and experiments. One of the main pieces of evidence is the redshift of light from distant galaxies. This redshift is caused by the Doppler effect, which is when the wavelength of light appears to stretch as an object moves away from us. The more distant a galaxy is, the greater the redshift is, indicating that the universe is expanding.
The Big Bang theory is the prevailing scientific explanation for the origin and evolution of the universe. It states that the universe began as a singularity, a point of infinite density and temperature, and has been expanding ever since. This theory is supported by the observation of the cosmic microwave background radiation, which is leftover energy from the Big Bang. The expansion of the universe is also predicted by the equations of general relativity, which have been tested and proven to accurately describe the behavior of the universe.
The expansion of the universe does not directly affect the motion of objects within it. This is because the expansion is happening on such a large scale, while the gravitational forces between objects are much stronger on a smaller scale. In other words, the expansion of the universe is not strong enough to overcome the pull of gravity between objects. However, over time, the expansion will cause objects to move further apart from each other.
No, the expansion of the universe happens on a timescale much larger than our own. The expansion rate is measured in terms of the Hubble constant, which is approximately 70 kilometers per second per megaparsec. This means that for every megaparsec (3.26 million light-years) of distance, the expansion rate is 70 kilometers per second. This rate is too slow for us to observe in real-time, but it can be measured through the redshift of light from distant galaxies.
Based on current observations and theories, it is believed that the expansion of the universe will continue forever. This is because the expansion is not caused by objects moving through space, but rather by the stretching of space itself. This type of expansion is not affected by the amount of matter or energy in the universe, so it is expected to continue indefinitely. However, this is still an area of ongoing research and our understanding may change as we gather more data about the universe.