dumbass is a nice name for a speed unit.
Speed of light in a true vacuum.
Speed of light through any non-vacuum decreases.
The speed of causality remains the same.
is the speed of causality tied to speed of light in a vacuum, or independent of it?
As I understand, the speed of light in vacuum is bound by the speed of causality. So, light would go at infinite speed, if it could (it being massless means any acceleration should result in infinite speed), but instead it goes as fast as the universe allows, which is the speed of causality.
If you consider light in motion as a wave (as it is in EM models and I think also in current mainstream physics) then you can’t expect it to work like matter. The speed of light is the speed at which EM waves propagate. Causality is the same because many interactions are mediated by exchange of photons via EM waves.
The speed of light in aluminium is ~0.95c, the EM waves in an aluminium antenna aren’t going to interact outside the aluminium faster than 0.95c. I would bet the effective speed of causality would never be greater than the speed of light in whatever medium the light is in
I’m no expert. I probably know too little about the propagation speed of a wave to understand what you mean there.
But here is a scenario where something is faster than light in the given medium: https://en.wikipedia.org/wiki/Cherenkov_radiation
As I understand, neutrons and gravitational waves are also bound by the speed of causality, because they have no mass. And I believe, unlike light, they are unaffected by electromagnetic forces that a material exerts, so they would presumably (always?) travel faster than light in that medium.
I will also say, that from what little I understand of this video: https://www.pbs.org/video/pbs-space-time-speed-light-not-about-light/
…it sounds like trying to determine the speed of causality by measuring it, is kind of backwards. You’re at best experimentally confirming what has to be a given under our laws of physics.If the photons were travelling faster than the local speed of light, why would light be emitted? The Cherenkov radiation takes away the excess energy as the light is immediately slowed as it moves from whatever radioactive metal to water
Gravity waves are indeed different. I don’t know the maths of relativity, but I bet those equations also require specific wave speeds. They don’t care about matter aside from it’s gravity which can bend space-time and change the wave path
I think we’re pushing this beyond both our understanding
Measuring causality/c despite those being given by our maths refines our values for the various constants
Both meters and seconds are units of Earth specific measures of space and time. Pretty sure at a cosmic scale god would give fuckall about how we measure and name our shit
Remember that light in motion is electric and magnetic fields pushing and pulling each other along. Why that speed? Because it takes time for an electric field to create a magnetic field and vice versa
Our equations for EM waves (Maxwell’s equations) predict light speed, and the same equations would predict c in any system, so long as reasonable values for the variables are known in that system
So 300 000 000 m/s isn’t going to be a reasonable approximation of the speed of light in vacuum, but any alien that one about radio would probably have Maxwell’s equations under some other name
1 Dumbass = 299 792 458 m/s
Thanks, God. We’ll spend the next 3000 years obsessing over that.
Nah, C is C. Who cares about the current hot measurements of space and time on a little rock, outside of us?
Little c for speed of light in vacuum
Anyone come up with a good measure of distance that makes the speed of light a nice round number? I like the metric system, but the meter feels pretty arbitrary. We could do better!
In radio electronics we abbreviate c to 300 000km/s (when working in kHz, different multipliers in other bands for easy maths). The number as it is is round enough when rounded to the whole hundred million for practical purposes with commodity hardware
We could redefine the metre to be 1.00069229…x it’s current size (increase it by 0.69229…mm) to make the speed of light exactly 300 000 000ms-1. This would also change area and volume, and any other units that are derived from length
Not arbitrary.
Since 2019, the meter has been defined as the length of the path traveled by light in vacuum during a time interval of 1/299792458 of a second, where the second is defined by a hyper-fine transition frequency of caesium.
I mean, that is pretty arbitrary. The reason the divisor is that specific constant is because we already had meters before we knew the speed of light.
Then it’s lucky the numbers line up as well as they do, no?
One light year is 9.4607379e+15 meters, so there’s a power of 10 that could give us a unit of length close to 94 cm. That would not be as arbitrary.
But fuck me if we discover the speed of light in a vacuum has not been constant along the history of the universe, the c would be an awful base for cosmic distance, or very long term science.
But don’t worry, humanity doesn’t look like it will exist long enough to do very long term science.
Because the CPU runs at 300GHz.
