Physicist: In terms of things like space travel, the difference between 100mph and light speed is academic. Everything out there is really far apart. The speed of light, “C”, is woven into the laws of the universe from top to bottom, mostly in the context of electro-magnetism. Changing the speed of light would have profound effects on chemistry and the fundamental forces.
But those changes are boring. What’s more interesting is the effects that special relativity would have on every day life.
For what follows, the speed of light is now C = 100 mph (161 km/h for our Canadian or otherwise foreign readers).
"Gamma" is a measure of how much velocity dilates time and shrinks distances. Most of the action happens beyond 90% of C.
Movement? Nopers: If you’ve taken intro physics you may have learned that the kinetic energy of an object is 
The first term is the famous rest mass energy (E=mc2), the second term is the regular kinetic energy, and the third, fourth, fifth (and so on) terms are only important when the velocity is a substantial fraction of light speed (so Newton can be forgiven for getting this one wrong). But if C=100mph, then suddenly those later terms become important even at low speeds, and you’ll find that moving as fast as 0.01mph would require something like a rocket or a nuclear-powered car.
But that’s boring, so let’s pretend that it isn’t the case.
No long range communication: 100mph is about 45m/s, so having a conversation with someone who isn’t close at hand will result in really annoying delays. It would be like those satellite interviews, only in person. To send a message to someone on the other side of the world would take at least 5 days and 4 hours at the speed of light.
I’m ignoring the effects, by the way, of the Earth rotating at about 1,000 mph (at the equator).
Leave your watch at home: The act of walking around would cause you to lose about half a second for every mile you walk, which isn’t to bad. But if you started moving around in a car at highway speeds (65 mph), then you could expect to lose about 17 seconds for every mile you travel.
“Super Speed”: One of the slick things about traveling at relativistic speeds is that, although you can only pass things at up to 100mph, you can actually cover more distance than the 100mph speed limit might imply. There are two ways to look at this.
From your point of view the world around you undergoes length-contraction. So, for example, at about 87mph you would see the world contracted by a factor of 2. So while you’d see things pass by at 87mph, you’d be eating up distance as though you were traveling at 174mph (2 x 87mph).
From everyone else’s point of view, you’re traveling through time slower. At 87mph they’d see your watch ticking at half the usual rate, so the trip will only take half the time it should.
Pretty colors: Even at running speed there would be enough relativistic doppler shift to change the colors around you. If you were driving past a yellow field of grain, it would appear blue in front of you and fade to deep red as it passed behind you.
There are just a hell of a lot of other effects, so if you’re wondering about any of them, just ask in the comments.
You say that there would be profound effects on chemistry. What are some examples? Would we even have organic compounds, life, or us?
“…and you’ll find that moving as fast as 0.01mph would require something like a rocket or a nuclear-powered car.”
You could also say for light to be forced to travel at 100 mp/h any movement in such a universe would have to be very energy demanding.
Otherwise the light would travel faster.
By dropping the speed of light, the “magnetic permeability of space” will have to jump tremendously. Essentially, magnetism would be a much more important force. I would guess that electrons would only show up in pairs. So odd numbered elements might only show up in ionized forms.
Beyond that I’d need a biochemist and a crazy ass big computer to look at the effects on protein folding, which is strongly influenced by magnetic interactions between different parts of the protein. I’d suspect that none, or almost none, of the proteins that exist in the world today could exist in a world with a very different light speed. However, in a world with a different C there might be all kinds of other fancy new amino acids and proteins.
Again, this is all guesswork. For anything more complicated than a single hydrogen atom we need giant computers and experiments.
Interesting. Chemical reaction would go slower, so it could affect the biochemistry in living organisms, and the speed ofneural impulses. The heat from stars and the center from the earth would not be able to leave their source at the same speed either. But as long as the heat was released just as fast as new one was building up, it shouldn’t be a problem.
I assume the inflation of the universe would still be the same. If so, the sky at night must be much darker, since the light from distant stars would require so many years to reach us.
And what if the speed of light was a million times faster than it is today, instead of much slower. Then the universe would perhaps be more available for us than it is today. Travelling thousand times faster than the present speed of light should be possible, and require less energy than a spaceship who has reached 90 percent of the 300 000 km per sec of today.
Another consequence is that it would be very hard to kill someone with a gun. A bullet couldn’t have moved fast enough to kill someone. A bomb going off would be a cool sight. Falling from Empire State Building would probably not be that dangerous.
Considering that the escape velocity from Earth’s gravity is about 11.2 km/s, one could say that most large objects would be some kind of black holes.
Classically momentum is P=mv. However, relativistically P=γmv. You can think of this as “things get heavier near light speed”. So while you might take a long time to fall off the empire state building, the end result would be about the same.
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would a bomb be a cool sight? if the other forces are left alone, i would imagine the shockwave of heat and death would hit you at the same time the light emanating from the explosion hit you? so maybe it would look cool for a nanosecond or something.
The idea of C being slower is interesting. How about if it were faster? Some people say it was/maybe faster in the past. My view is that we could detect that via astronomical observations. For example. Einsteins E=mC2 would mean fusion reactions would be considerably hotter, that the fine structure constant Alpha would be different, and magnetic fields would be weaker.
Is there a value of C such the stars could no longer form?
Thanks
christopher: The shock waves from the bomb would not emanate as fast as the light from the bomb itself. due to lower C, the shockwaves would emanate super-slow.
If you want to know what its like, MIT made this into a video game.
http://gamelab.mit.edu/games/a-slower-speed-of-light/
The science community seems to readily accept the idea of radioactive decay. Has it ever occurred to any one that perhaps other things decay, too, such as time and the speed of light? Does the main posted document sort of speak to maybe the latter?
what will happen to sound waves
Actually, to outside observers everthing would be going faster or slower dependent on the increase or decrease of the speed of light. To the inside observers, nothing would change. The medium for light is the framework for all that we observe in our universe. Therefore it’s soley responsible for supporting all mass and their properties. Think of the void, or aether, as what is called the time dimension, since it controls the speed of light, the only difference to the other dimension would be their relativistic passing of time.
Sorry I don’t mean to make it seem as if I am trying hijack this thread however…
To ponder the question is superfluous in my opinion.
That is due to the fact that light is traveling at different/varying speeds in different parts of our universe anyway due to the existence of objects of varying mass. You cannot get “All” light in our universe to travel at a constant speed relative to any one point.
The light constant varies ever so fractionally in minute amounts to to it’s instance being affected by proximal gravity relative to the entire universe. It is not a precise constant. It is a fractionally varying constant.
The only thing you can do is create isolated instances of light that travel slower or faster.
For example.
Create a centrifuge with a laser mounted on the rim pointed inwards towards the center . In theory if you fire the laser towards the center of the centrifugal orbit, while centrifugal force is acting upon the photons, the light/photons would take longer to arrive to the center due to to the photons traveling slower. In theory, the faster the centrifuge spins, the slower light would travel relatively, until photons would be standing still/frozen. Of course the mass of the centrifuge’s rim would be astronomical at that point.
Alternatively you could create a “tractor beam” to do the same job, rather than a centrifuge. It is possible, and research and use of element 115 in an antimatter reactor as reported by Bob Lazer, actually does create a tractor beam effect, and a side effect is the slowing down of light particles.
Bob Lazar, while working at area 51 claimed that he entered an alien spacecraft that used technology to travel to distance parts of space by aiming a “tractor beam” at a location in space and pulling the craft towards it in order to travel there.
When Bob Lazar entered the reactor room on board the craft that housed the antimatter reactor that created the tractor beam energy through 3 cylindrical modulators at the base of the craft, a candle that had been previously lit in the reactor room seemed to show it’s flame “frozen”, so he claims.
I myself have studied the effect using different waveform signatures and a tractor beam can definitely be created without element 115. I think there is much more to science fiction than meets the eye, such as the “light sabers” from the movie Star Wars. They are basically small tractor beam laser light emitters that freeze laser light at any predefined length using the described elements stated above.
What would really be interesting is:
What if we could get light moving faster than it’s maximum varying constant value?
What would happen?
Any comments highly appreciated…
The effect would be that our Universe as we know it would be entering the Big Crunch phase, and turning into a black hole.
Speaking relatively, there would be no real difference, just that everything would appear to go slower, at least for the observer. We, humans, use light to measure time so the speed of light would affect our proception of time.