Do protons accelerate or do they just start off at full speed. hard to imagine something with no mass having a limit on it’s speed.
But this sort of begs the question. Why is c 3x10^8 m/sec, is really asking why seconds are 3x10^8 meters long. The reason is that we have arbitrarily decided the length of a meter and the length of a second to be convenient, and those choices happen to result in that conversion ratio in space time.
More interesting is if you start putting various physical constants together in such a way that they cancel out, then they stop being arbitrary and start representing fundamental aspects of our universe. For example why is the ratio between the weights of protons and electrons what they are? No matter what units we use for weight, that ratio is a constant.
There is a similar equation that says c is approximately equal to
137.036(e^2/(h \epsilon ))
where e=charge of the electron, h=planc’s constant and \epsilon= the permiability of space.
Why 137.036? if you can figure that out you’ve got a good shot at a Nobel prize.
I assume you mean photons?
I assume you mean photons (not protons), and yes, they are always moving at c. In a medium there is some bouncing around so its effective speed is slower, but there is no “getting up to speed”. Any event that produces a photon produces one that is moving at the speed of light.
We define that fundamental slope to be c. If it were something else, we’d define that something else to be c. Really, it’s more natural to refer to the fundamental speed as 1, except that, for historical reasons, we usually use different units to measure space and time.
You’re over-privileging electromagnetism. The fact that there is a maximum speed is the fundamental truth, and electromagnetism just happens to travel at that speed, or so close to it that we can’t tell the difference. But, for all we know, it’s possible that photons do have a mass, just an extremely tiny one, in which case they would have a speed that would depend on their energy, and be very, very close to c for any energy large enough to measure, but still be slightly slower. This actually happened with neutrinos: We used to think that neutrinos were massless and hence travel at c, but we now know that they’re not, and are slower. If, during the early era of the discovery of the neutrino, we had taken to calling the maximum speed of the Universe “the speed of neutrinos”, we’d now be very disappointed.
Really, that’s not even a question about c. It’s a question about the units we use. c is 1, and 1 is not a value that inspires us to ask “why”. One meter per second is much less than 1, and has the particular value that it does, because 1 meter is 1/40,000,000 of the polar circumference of the Earth, and 1 second is 1/86,400 of the average synodic period of the Earth’s rotation.
Right, now that is a genuinely interesting question. And, like many genuinely interesting questions, the answer is “we have no friggin’ clue”.
100% is 100% because it’s 100%.
Now if we ask how big is 100% relative to the speed of a single HP engine, pulling 1 ton on a steel track, in a vacuum, at sea level, then obviously that’s going to be a fairly arbitrary percentage off of the maximum (100%) speed.
Perhaps the question can be asked differently.
The speed of causality is 299,792,458 m/s. Is there a reason it is 299,792,458 m/s, and not (for example) 299,792,459 m/s?
I am guessing there’s no answer to the above question.
The answer to that question is because that’s the way we chose our units. 299792458 m/s is no more nor less fundamental than 2.54 cm/inch. Could we instead have defined 1 inch to be 2.55 cm? Sure, we could have. But we didn’t. And one way or another, it doesn’t really tell us anything at all about the world itself.
IANA physicist, and my understanding of the universe is pretty shaky, but isn’t the speed of light considered to be the speed limit of the universe, because we haven’t found anything that travels faster than light? And if somewhere, somehow, we found some subatomic particle, or force like gravity pulling everything into a black hole faster than the speed of light, wouldn’t we be forced to redefine c to be that speed?
We can pretty precisely determine the value of the speed that shows up in the relativity equations, by observing various relativistic effects. If we ever observed anything moving at a speed clearly greater than that, we’d be well and truly stumped.
This is exactly what I am talking about. That is not an answer, you are arguing the number comes from the units. Why isn’t c 10% faster than it is? Why isn’t it 5x10^100 plank units per second? Your answer is like if I asked why Bugatti has a top speed of 305 mph and instead of the engineering, limiting factors of friction on asphault, &c. you say its because in 1 hour it goes 305 mile but if you measured it in meters per minute you would get a different number (although not a different speed).
Why isn’t the number 1 10% bigger? If you can answer that, then I’ll answer your question.
Because it’s the same question.
Einstein came up with his theory of relativity based on confusing observations of the universe.
The original theory was the aether, that there was this invisible virtual medium which light travelled in (otherwise, what was light?). The theory was, if we observed the speed of light of, say a distant star when earth’s orbit was moving toward and away, we should see different speeds of light. (interfereometry experiment). Instead, it was measured everywhere at the same speed.
What are the implications of a universe where no matter where you are, not matter what speed and direction you are going relatvei toeveryone else, evey light source you see is travelling at the same speed? And yet if your buddy is travelling with regard to you, he measures the same speed of light from the same source. By newtonian physics, that we are all familiar with, he should see different.
Work out the math, and the answer is - time slows down, distances shrink, relative to other observers moving with respect to you, so you both see the same thing. Followed by the paradox that there is no such thing as simulataneity for events in different place, and all the other strange effects of Eistein’s calculations…
That’s still my question, too.
Rightly or wrongly, I look at c as an absolute speed.
Let’s say I take a meter stick and put it on a table. At one end I have a flashlight. I turn on the flashlight. The light beam will reach the other end of the meter stick in 3.33564095198152 nanoseconds. (It will actually take slightly longer due to air, but I’m ignoring that.)
For the exact same meter stick, why doesn’t it reach the other end in 3.34 nanoseconds? Or 3.32 nanoseconds?
Expect the reply, “Because that’s how we define the second. If you change the value of the second you’ll get different numbers.”
Because that is how we defined the second.
Asking why we usefully define c as 1 is missing the point. So far as we understand the working of the universe, the speed of causality is one of the absolute fundamental building blocks. The mere fact that there is a speed of causality is part of the basic fabric of everything. So, being so basic, we can use it as a unit from which we derive many of the others.
The metre is defined by measuring the size of the Earth. The second is derived by measuring the period the sun rises and sets. Not exactly fundamental to the nature of the universe. So in our tiny self centred view of the universe, we come up with silly numbers to express the speed of causality. The reason they have the values they do, and not others is due to the accidents of history that got us the units we use.
The permittivity and permissibility of space don’t define c, they are clearly dependant upon c. That taken together we can derive c from them isn’t mking them more fundamental.
Why isn’t 100% 10% larger than it is?
I don’t know if this will be helpful. The answer to your question is that ‘faster’ is not defined past the speed of light. Maybe this doesn’t make sense here, but ask yourself why something can’t move slower than 0MPH. You’ll end up trying to divide by 0. Definitions of ‘speed’ in terms of units/units break down at both ends of the scale.
While that is a true statement in the context of Special Relativity, it isn’t very helpful in addressing the question of the o.p. and others.
Fundamentally, the speed of light, c is related to two other natural constants, the electric permittivity of vacuum, ε0, and the magnetic permeability of vacuum, μ0 in a specific ratio. And if either of these values were different by even a very tiny proportion, we would have a very different universe from the cosmological scale right down to the subatomic level even if the relative behavior of spacetime was the same. “Why” is the physics of the universe this way is a kind of open ended philosophical question for which we have no answer, other than that if it were different we wouldn’t be here to ask that question, and indeed, there might not be any kind of stable chemistry or the ability to even form elements.
This just isn’t true; while massless particles can only move at c, and massy particles at some relative speed less than this, it is certainly possible to measure displacements of greater than c (for instance, the lateral sweep of a laser across a distant field), and of course spacetime itself is expanding much faster than c beyond the cosmological horizon.
Stranger
I’ll try again. What is it about the structure of the universe makes the velocity of light what it is instead of something else like 15 mph?
Why is it with all units staying the current magnitude that they are that c is not 50% of it is? I know that is tricky as the meter is defined via c so for the sake of argument assume we convert the current length of a meter into a perfect physical artifact that keeps its length even if the speed of light changes.