Science and Inquiry discussion
Issues in Science
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How can the universe be so big?
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Ah! Thank you. Space is expanding, thus not limited to the speed of light.
... although what exactly it means to say that there's a difference between 'space expanding' and 'objects moving apart relative to one another' is a more subtle discussion which, as far as I'm aware, has not yet been fully addressed.
I'm sure it's beyond my understanding & curiosity. I had just enough math to get a very old & basic intro to quantum physics 40 odd years ago. I'm more of a Newtonian sort. I appreciate & applaud that the big brains have figured out just how weird things get at the extremes of scale, but that's it.
True, but occasionally the big brains are a bit too big for their own good! There's a temptation to be led solely by the maths on this one, but I think there are still real questions about the physical interpretation of what the maths says is going on. At least, I never got an answer that fully satisfied my own understanding on this when I was in research. I'd suggest remaining a healthy 10% skeptical :)
I agree, Piers. Nice to know someone with your credentials feels the same. I've always been skeptical of the idea of dark matter & energy especially in such large quantities. After reading several explanations of why we think it's there over the years, I've decided that probably some early measurement or equation is slightly off & is compounded. That's a completely personal & ignorant belief, though. I usually detest those, but I can't see how it can affect my life or actions. I felt the same way about the popularized accounts of 'junk DNA'. Indeed, it turns out that much of what was deemed junk isn't. It just wasn't directly used for coding, but has important job(s) to do in spite of that. There's still a lot we don't understand & simplified explanations often don't reflect that as accurately as they should. We're built to want definite answers rather than accurate ones.
The universe is about 13.8 billion years old, so any light we see has to have been travelling for 13.8 billion years or less – we call this the 'observable universe'. However, the distance to the edge of the observable universe is about 46 billion light years because the universe is expanding all of the time.
https://phys.org/news/2015-10-big-uni...
I thought the universe started as a dot & exploded 13.8 billion years ago, so could only be 27.6 billion light years across if everything moved away from that point at light speed. I'm wrong in my understanding somewhere & would appreciate some help.