In looking at the answers to this question regarding light from distant galaxies ever being visible to us:

Expansion of the Universe, will light from some galaxies never reach us?

I came across a few concepts that were quite surprising to me. In particular:

  • Movement faster than the speed of light

  • The big bang was not an explosion outwards from a single point.

Granted I am just a rank beginner and self-studier, yet I did study a QM course from Oxford, have read several sets of notes on SR, and readily went through the first hundred pages of "Student Friendly QFT."

Yet I have never encountered these notions.

My question is where does one acquire this type of information. Not necessarily the technicalities (of, e.g., GR); but just a correct awareness.

  • 1
    $\begingroup$ Nothing is "moving" faster than the speed of light. The proper distance between us and a photon moving away from us will increase at a rate faster than the speed of light when expansion is taken into consideration, so light is still "moving" faster than anything else $\endgroup$
    – Jim
    Aug 9, 2014 at 18:21
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    $\begingroup$ Most people you will come across that know the correct version of this kind of information are physicists who also know the technicalities of the physics behind it. However, some are also people who know or have talked to physicists and learned the "truth" from them. $\endgroup$
    – Jim
    Aug 9, 2014 at 18:23
  • $\begingroup$ I don't know of any source of the correct, non-technical awareness. Physicists have always tried to find ways of ending the popular and incorrect beliefs about some concepts. Thing is that popular science/media gets ahold of a concept, doesn't really understand it, then presents it to the public as wrongly and as fact. This then spirals out of control and we end up with the big bang being an explosion outward from a single point. $\endgroup$
    – Jim
    Aug 9, 2014 at 18:26
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    $\begingroup$ There's no easy way of explaining all the concepts without explaining the technical stuff. At some point, intuition and/or relatable experiences fail us and the only way to understand something is to go through the technical stuff $\endgroup$
    – Jim
    Aug 9, 2014 at 18:28
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    $\begingroup$ What you have discovered is that physics is a big discipline. There are several users on this site who are out-and-out experts in one subfield or another and moderately naive in others. That's just the nature of the beast. $\endgroup$ Aug 9, 2014 at 21:08

2 Answers 2


Your question and this answer are really better suited to the Meta, and I suspect a moderator will be along some time soon to migrate them. But while your question is still here ...

An intuitive understanding of GR is extraordinarily difficult to attain. I've been studying GR (as an interested amateur not a pro) for a decade and I still make naive errors from time to time - ask any of the pros hereabouts, they've all done their share of correcting my errors :-). Unless you're prepared to put in the considerable effort to learn about the subject the best way to pick up on things like the nature of the big bang, cosmological horizons etc is to ask a physicist.

And that is what makes the Physics SE so immensely valuable. It gives you access to real physicists who do physics every day and know enough about physics to be able to explain it at a popular science level without doing too much violence to the underlying principles.

Of course Googlespace is an immensely valuable resource, and you should do all you can to research questions before posting them here. After all, the population of question answerers here is finite, and not that large, and it would be easy to swamp them. But if after reading around you still need to know more about Physics then the best way to do it to ask here.

  • $\begingroup$ Found it - space expands with time. Thanks very much for your eye-opening remark. $\endgroup$
    – user41976
    Aug 10, 2014 at 11:31

Theoretically, if a galaxy is far enough away and the universe ends or we become extinct, then it would never reach "us". Unless there is a distance that, once traveled, light dissipates to nothing, which seems unlikely, given ample time it will all reach "us" eventually.


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