This question is prompted by the news that the telescope at Hawaii’s Gemini Observatory has just taken a snapshot of the most distant object in the universe, a gamma-ray burst some 13 billion light years away, and consequently, of course, an event which happened 13 billion years ago when the universe was forming.
This made me think about what we are seeing when we look at the night sky: a chaotic patchwork of stars and galaxies from different times in the history of the universe, from a couple of years ago to 13 billion years.
So what if the speed of light were far, far greater, fast enough to travel across the universe in the blink of an eye. Do astronomers have any idea what the sky might look like if we could see everything in the same time frame? Would it be far more crowded? Less crowded? Or is there just no way of knowing?
And if the speed of light were that much faster, would we notice any differences in our everyday lives, other than a changed night sky?
This is a really interesting question. I don’t know anything about cosmology so I don’t know if scientists have ideas about how many stars have formed but their light just hasn’t reached us yet. I think they have a pretty good idea how many we see today that are not really there anymore.
As far as impact of daily life back here on Earth, there would be no delay in long-distance radio transmissions (like those that bounce off of satellites). If EM wavelengths stayed the same, then frequencies would be insanely much higher. Biological structures may be able to adapt to that but I’m not sure of the limits of what they can do, so there is a question of whether we could develop vision comparable to what we have today. Come to think of it, not sure if we could develop radio technology, either.
Well, there wouldn’t be that annoying delay between turning on the light switch and seeing the room light up. Every nanosecond counts.
I would suspect that the wavelengths of EM waves would be the part to change. The processes which create EM radiation tend to create frequencies (think radio oscillators), and the wavelengths just follow by the nature of c.
From my understanding, the difference is we wouldn’t exist. The entire sky would be as hot and bright as the surface of a star; check out Olber’s Paradox. I doubt Earth would even exist - anything as small as it would boil away.
We definitely wouldn’t be here to see it, as electrons wouldn’t interact the way we expect them to. Setting c to a higher value means setting the permittivity of free space to a lower value, as c=[sup]1[/sup]/[sub]sqrt(ε*µ)[/sub]. So chemistry goes right out the window.
Thanks to Der Trihs and Whack-a-Mole for the links to Olber’s Paradox.
I tried to read it. I really did. But there’s one question in my mind that I just can’t get past, and if anyone can help me with it, I’ll reread that article and rejoin this conversation.
My question is this: I understand that if the sky is filled with a literally infinite number of stars, then 19th Century people would have concluded that the sky would be super-bright. But that has nothing to do with the speed of light.
In fact, as I see it, even if the sky started out with an infinite number of stars, the sky would be super-bright ONLY if those stars had eternal lives. But with the current understanding of stars being born and dying, it seems to me that the OP is really asking “Which stars that we see don’t exist any more? And how many new stars would we see if the speed of light was faster?”
Hmmmm… There is a contradiction in the above paragraph. If stars are being born and dying, then it’s not possible for there to be a literally infinite number of stars. The whole Olber’s Paradox was built on the idea that such a thing might be possible, but today we believe that it’s not. So we don’t need to worry about it.
A world where the speed of light was greater would be indistinguishable from our world. All of our units are ultimately derived from the properties of physical objects, and those physical objects ultimately derive all of their properties from the fundamental constants of the Universe, one of which is the speed of light. So if the speed of light were faster, then we’d also have longer metersticks and/or faster clocks, and so would measure the same speed for it, in (distorted) meters per (distorted) second.
Chronos what about E[sup]2[/sup] = m[sup]2[/sup]c[sup]4[/sup] + p[sup]2[/sup]c[sup]2[/sup]
I’m probably not thinking clearly, but this seems like a disaster. Are you thinking that there would still be a constant, say k, that would be equal to 3X10[sup]8[/sup] m/s?
oops I missed your last sentence. But wouldn’t it infinitely distorted?
But there are other constants. They are sometimes related to c, but (correct my ignorance if I am wrong) they are not purely derivative of it. G, Planck’s constant, the fine structure constant, the elementary charge constant come to mind. If c changes but not the others, is there not necessarily some distortion of the universe? Does not the fact that we can measure the speed of light in any units at all mean that there is some “capture” of c within a universe governed by more constants than just c?
My ignorance begs to be corrected.
I was just reviewing (highschool) astrophysics and cosmology. The two main answers to Olber’s paradox: one is that stars have finite lives, and the other is that because of the finite age of the unverse, light from only a part of the universe can reach us. So if the speed of light was infinite, then light from every star in the universe will reach us, which may be enough to heat up the Earth enough so that we would not exist.
I do not think the OP was positing different frames of reference such that faster light speed means everything else adjusts so all seems “normal” in that frame.
I think the OP was asking what if instead of seeing a star (or quasar*) 13 billion light years away light traveled essentially instantaneously to us so we saw it as it is now. Star 4 light years away same thing…we see it as it is now.
So, essentially all the light from all the stars in the whole universe would be piled on us in one gigantic pile hence the reference to Olber’s Paradox.
If light did travel instantaneously (i.e. infinite speed) then I think our frame of reference would be time frozen. That is we’d all be stuck in one moment and stay there till the universe ended…if it could end being entirely stopped like that (brain meltdown time).
*[nitpick]
I should note Quasars are actually long gone from our universe so if light traveled that fast you would not see a quasar out there.
[/nitpick]
But we’d only be seeing light from stars that are currently radiating light, not stars that no longer exist or are no longer shining. And there’s already billions of years of light that came here in the past, that we’re no longer seeing. And don’t forget that distance still matters. We may be seeing light instantaneously from stars 13 billion miles away, but it’s still diminished by all that distance. Not to mention dark matter and other obstacles.
Unless I’m missing something (and I probably am), I think the sky would look pretty much the same as it does, except all the distant stars and galaxies would look older.
This nitpick is not a minor point. Rather, it is exactly what destroys the paradox. If light was instananeous, we would not see any dead quasars or dead stars. There would not be any “gigantic pile”. The sky would look pretty much as it does now.
I don’t think I understand how Olbert’s paradox figures into this. Olbert’s paradox is talking about an infinite universe of uniform distribution. We know that’s not the case regardless of the speed of light. Am I missing something?
In any event, I can’t see that instantaneous travel of light would significantly affect what we see. The brightest stars are the closest ones, and what we see wouldn’t change much regardless of the speed of light. Even the nearest galaxies are only a few million years old in our view; that’s just not very old in astronomical terms. Quasars and ancient gamma bursts wouldn’t show up and some newly formed galaxies would show up, but anything ten billion light years away isn’t visible to the naked eye.
What it comes down to, is the only things which can be meaningfully said to change are the dimensionless quantities, because for all the others, you have to ask “changing relative to what?”. So one can speak meaningfully of the fine structure constant changing, or of the proton to electron mass ratio changing, or of the ratio of a particle’s mass to the Planck mass changing, but one cannot speak meaningfully of c changing, or hbar changing, or G changing. A few years back, there was some talk of “evidence that c has changed over the history of the Universe”, but what the evidence (such as it was; even the researchers reporting it acknowledged it was pretty weak) was really pointing to was that the fine structure constant had changed. One can interpret this as meaning that c has changed, but one can also interpret it, as least as easily, as meaning that the charge of the electron has changed.
And Ring, I was assuming that the speed of light was “almost infinite”, which is to say much larger than it is now but still finite, so that all of the corresponding distortions would be very large but still finite. A truly infinite speed of light would require such an extensive overhaul of the laws of physics as we know them that I wouldn’t even know where to begin.
This “almost infinite” is difficult. If you made the speed of light 1000000000 times greater than it is now, would that count as almost infinite? Because it is much slower than 10^5000 times greater. And that is fantastically slower than 10^(10^5000), which is still way less than half of infinity, way less than one percent of infinity. Etc etc.
I think something else is wrong with the way we are looking at all this. The “speed of light” is two things - it is how fast light travels, and it is also the constant “c”, which is an important piece of how the universe is built. Our conversation would be healthier if we had known of “c” all along and learned of its wonderful powers, and then only recently found out about light and the fact that it propagates at c. I think it is very much an integral feature of the universe that it doesn’t all exist at once, or rather that it exists in a way that is specially centered around us, with plenty of very old things nearby and off in the great distance only younger and younger things. It’s not some artifact of the way we use light to observe it - the point is that this old-center and young-periphery structure is a fundamental truth about the universe, very specially centered around us, and also very specially centered around every other location (to grok this is to get the whole thing).