I find it’s simpler to use a slightly larger mile, so it comes out to exactly 186,000. Adjust your odometers accordingly.
I actually often wondered as a kid why they didn’t define a meter as being exactly 1/300 000th of the speed light goes in a second.
The meter is defined in reference to the earth, not to the speed of light. It originally was one ten-millionth of the distance from the Earth’s equator to the North Pole but has been refined since then.
The meter is defined in reference to c, not the Earth (any longer).
Even more precisely, I’d say that a mathematical description of light is in some ways like the math for an idealized perfect wave (and is in other ways like the math for an idealized perfect point particle (and in other ways like neither)). Don’t know if that’s any clearer, though.
Actually, the speed of sound does depend on the speed of air molecules. That’s really what sound is: air molecules banging into other molecules next to them, which knocks those molecules through space to bang into more molecules a little farther along, etc. [Light of course is very different from sound]
Maybe the light isn’t traveling in a wave. Maybe space is bent.
tokes
Nothing can travel faster than c!
Farnsworth: Of course not. That’s why scientists increased the speed of light in 2208
The double-slit experiment would beg to differ.
When you do the experiment the resulting picture on the screen behind the double-slits is exactly what you would expect of waves and not particles (you get an interference pattern).
However, if you mess with the experiment in certain ways (e.g. try to determine which slit the photon passes through) the waveform collapses and the light behaves as a particle and the results on the screen will reflect that (no interference pattern).
That’s true, I was imprecise.
The original definition of the meter was based on the size of the earth. And that is the answer to the question of why it wasn’t chosen to be a round number in relation to light speed which is what I was answering.
Ok it does. I meant “equal”.
Light really is a wave (among other things). It really is not, however, a squiggly line.
It doesn’t “beg to differ”. The light is still travelling in a straight line, it’s just been interfered with along the interference pattern, cancelled out by the other light that happens to have its inverse wave intensity along those points.
The squiggly bits don’t really move, they are just there with the light. If you measured them, obviously yes they are longer than the unidirectional light. But they are not a “thing” that’s travelling, you could consider them an electromagnetic field given off by the light. It’s the same with all electromagnetic waves.
Light (or, more generally, electromagnetic radiation,) as it propagates from point A to point B at a speed of c, does, in fact, travel in a straight line. The method of propagation involves Maxwell’s equations relating electric fields and magnetic fields.
When a stationary electric field is formed, the field, itself, will diverge. Any charged particle will be affected by the field, in direct proportion to the strength of the field at that point. The rate at which the electric field diverges is proportional to thepermittivity of free space. Nothing physical is actually moving as the electric field grows.
A consequence of a changing electric field is that it causes a magnetic field. The magnetic field grows and diminishes as a direct consequence of the change in the strength of the electric field. The rate of change in the strength of the magnetic field is proportional to the permeability of free space.
The existence of a changing electric field causes a magnetic field, and the existence of a changing magnetic field causes an electric field.
It turns out that the rate of change of these fields causes a wave-like change in field strength to propagate in a direction at right angles to the field, at a velocity determined by the values of the permittivity and the permeability of free space. This velocity turns out to be equal to the speed of lightin a vacuum. Note carefully that nothing physical is moving in a transverse sine wave. The amplitude of the wave-like change in field strength may be sinusoidal, but no physical particle is moving “faster than light” along that path.