I've heard that because light takes time to travel from one place to another, we see objects in distant galaxies as they were when they released the light. new and advanced telescopes are able to see further and further into space, and therefore closer back in time to when the big bang happened. I've also heard that the laws of physics are slowly changing over time and that they might have been different in the early seconds of the big bang. In the future, could an advanced telescope be used to observe the light released by distant galaxies and other cosmic structures at the time of the big bang and observe physical laws that were different from the ones that we have in the present day?
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1$\begingroup$ The answer is Yes, we may observe distant phenomena that are inconsistent with our current understanding of physics, and push us to update our theories. One good example is dark matter. We've found from measuring the mass and motion of galaxies that either our understanding of gravity is wrong, or there is a huge amount of hidden mass that we cannot observe (yet) to explain the observations. $\endgroup$– RC_23Commented Jul 28, 2023 at 14:05
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2$\begingroup$ There were no galaxies at the time of the Big Bang (or at the earliest time that we can see, when the CMB was released). $\endgroup$– D. HalseyCommented Jul 28, 2023 at 15:33
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1$\begingroup$ Welcome Hannah to Physics Stack Exchange. The oldest observable "light" is the CMB from about 400,000 years after the Big Bang. It is not impossible, however, that future neutrino "telescopes" could observe the Cosmic Neutrino Background from about 1 second after the Big Bang. Looking at distant galaxies might tell us about possible changes in the laws of physics (e.g. changes in fundamental constants) starting from a few hundred million years after the Big Bang. $\endgroup$– David BaileyCommented Jul 28, 2023 at 17:27
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The oldest observable "light" is the Cosmic Microwave Background (CMB) from about 400,000 years after the Big Bang. It is not possible to directly observe any electromagnetic radiation from before that time.
It might eventually be possible, however, that future neutrino "telescopes" could observe the Cosmic Neutrino Background(C$\nu$B) from about 1 second after the Big Bang. This would be a very, very difficult challenge, and we have yet to achieve even the first step of simply detecting the C$\nu$B.
Even if we can't look directly back to the big bang, we can still look for changes in the laws of physics.
- If the laws of physics governing the formation of the CMB were different from what we believe, this could produce discrepancies in the CMB we observe today.
Looking at distant galaxies and other early astrophysical objects can tell us about possible changes in the fundamental constants over time:
- Observations of distant galaxies set limits in changes the electron-proton mass ratio.
- Measurements of quasars have set limits on changes in the fine structure constant, and even turned up some weak evidence that it might have changed.
- Distant supernovae can be used to set limits on changes in the gravitational constant.
Future telescopes could push these observations back to when the earliest galaxies formed a few hundred million years after the Big Bang. Already, the JWST has produced some surprising observations about early universe.
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answered Jul 28, 2023 at 20:43