Morkonan wrote:Incubi wrote:I did not get the part as to why it is divided by light in the first place. Would it not be the same result if you divided it by the speed of sound or just any other number?
This I am not sure of and perhaps red assassin would like to comment on that.
I would think it's because the speed of light is constant in all reference frames and the Lorentz Transformation is about how space-time contracts in relation to a frame of reference. So, the introduction of a constant enables a meaningful value.
Unfortunately the answer to this is effectively "because it's a fundamental property of the Universe". It's nothing to do with light in particular; quite the opposite: light travels at the fundamental maximum speed because it has zero mass. You are quite correct that this maximum speed is the same from any reference frame, and thus light will be observed to travel at the same speed from any reference frame.
This property was originally derived from the Lorentz equations of electromagnetism, which successfully predict the existence of an electromagnetic wave, but produce a wave with a constant speed which is not dependent on reference frame. This fundamental incompatibility with Newtonian mechanics is what led to the development of relativity.
There's no particular intuitive reason that this should be the case, however, or why the maximum speed should be what it is; this is simply how we observe the Universe to be.
If we could devise a way to stand on a light beam. and then allowed the light beam to carry you at the speed it travels. what would prevent you from traveling the speed of light then?
It doesn't matter. (Besides, that is an excellent Troll Science piece, if you haven't seen it.
Google "Troll Science.") What mattes is that you are still trying to accelerate something with mass (you) to the speed of light and that won't work. Even if you had something like a neutron gun which, despite being disproven as superluminal, shot out superluminal particles that were capable of propelling you, you still wouldn't be able to accelerate to lightspeed because the energy necessary would continue to increase until it reached the infinite. (Though, I'm certain someone will try to chime in and tell me how wrong I am..)
Curiously, as I recall, imagining riding on a photon travelling away from the clock tower in Bern is how Einstein claimed to have come up with the basic principles of relativity.
Anyway, since you have mass, you would require infinite energy to travel at lightspeed. It doesn't matter how you try and gain said energy.
Those not following Morkonan and myself's other discussion may wish to tune out at this point.
What you're describing is the way in which *any* moving object is drawn on a screen - by illuminating fixed pixels at the correct times. You don't need to do anything different to draw something which appears to cross the screen at the speed of light; you just need fast enough components. There's no fundamental difference in any sense between drawing something moving at 0.3m/s, c, or 100c. While there will be an upper limit on how fast an object you can draw, this has no dependence on the real-world speed of light and solely depends on the resolution of your system and how fast you can switch components on and off.
To illustrate, I could, right now, with readily available components (though, granted, rather a lot of them), construct a simple display showing an object passing much faster than the speed of light. Here's how:
First, for the pixels, we're going to want a bunch of simple systems with a network connection and a digital output. An Arduino or something similar should be entirely suitable for the job here. Let's take ten of them. Now, we connect an LED to a digital output on each, and then we give each of them an ID number, and we program them to turn their LED on for a thousandth of a second (an Arduino+LED probably isn't quite that fast, but it's close, and at any rate a good monitor will switch this fast so it's entirely possible to do) when they receive a network packet containing their ID number.
Now, we're going to need an awful lot of fibre-optic cable, and we're going to equally space our Arduinos around the equator, connected up with the fibre-optic cable.
And now, we take a computer which will be the controller. At this point, we note that it takes light about a tenth of a second to perform a lap of the Earth (this isn't quite right, but it'll do as an order-of-magnitude estimate). And we set the controller up so that it transmits packets in reverse order, such that the packet for the 10th Arduino which is almost all of the way around the Earth is dispatched first, at -0.1 seconds for the packet's transit time +0.01 seconds for the result's transit time, followed by the 9th Arduino's packet at -0.09s packet + 0.009s result, and so forth, until the Arduino closest to the controller gets its packet transmitted at time 0.
(Obviously, lag will be introduced into this process by the network which is not distance-dependent, but this is constant for each device and so can be ignored.)
And the result of this is that the Arduinos receive their packets at 0.001 second intervals around the Earth's circumference, and our crude screen then shows an object which performs a lap of the Earth at ten times the speed of light. And this has all been done with a single clock, on the controlling system, no trickery, and nothing implausible with current technology. All I've done is increase the spatial separation of the pixels sufficiently to compensate for the 1ms-level switching of a display pixel, and at no point has the true speed of light had any effect on anything other than how early I need to dispatch my packets.
Edit to clarify the point here: While there will be upper limits on how fast an object you can draw, they depend on arbitrary parameters of the system other than the speed of light, and so in the majority of cases the maximum speed of an object you can draw is not going to be equal to the speed of light.
As an aside on clock speeds relating to relativistic limits, relativity does govern the maximum rate at which information can be carried. It's somewhat hard to tell how far it needs to be carried across a processor in a single clock tick, but given light travels 3cm in 0.1ns, which would correspond to the tick rate of a 10GHz processor, we might not be too far off hitting that limit. It's probably within an order of magnitude or two. Increased clock speeds have been found to be inefficient for other reasons, though, which is why clock speeds haven't really changed much in the last few years, with processor computation speed improvements coming in other ways.
A still more glorious dawn awaits, not a sunrise, but a galaxy rise, a morning filled with 400 billion suns - the rising of the Milky Way
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