Fickle Physics

[Arathena]

... And I can't even get my units right, so. (km/s earlier, not m/s).

Seeing the friggin obvious is what physicists are for. I mean, who really knew two balls of different weights fell at the same rate till Galileo dropped his balls off the tower of Pisa?

That said, um, when you find a device capable of moving through a fluid at 0.75 c(0), I wanna take a ride.

[Ddrak]

That said, um, when you find a device capable of moving through a fluid at 0.75 c(0), I wanna take a ride.

Ok. Here's the deal. You find the sub and I'll let Layani drive. I guarantee you she'll find a way of making it do 0.75c.

(And it's 3x10^5 km/s, not 10^6)

Dd

[Arathena]

Sigh. At least I got the 2.998 right.

[SicTimMitchell]

who really knew two balls of different weights fell at the same rate till Galileo dropped his balls off the tower of Pisa?

Nice to know even real physicists can fall for the classics.

[Arathena]

It's a better story than the real one.

[Embar Angylwrath]

c itself is a localized material of transmission dependant variable

I know strictly speaking this is from absorption and retransmission of photons but it always made me wonder what you would see if you were in a submarine travelling at something beyond the speed of light in water...

Dd

Besides Klast's fantasy for green chicks, you see on that instrument panel an absolutely ferocious storm of high energy photons that you're blazing through much like the sonic boom cone of a supersonic aeroplane - You shed energy, and momentum by twanging the accumulated EM field of the local medium, until such time as your velocity is beneath local c. This 'luminal boom' is called Cerenkov radiation, and it's the source of the pretty blue-green glow in a reactor pile. Electrons are ejected from the pile at extreme fractions of c(0), much higher than c, and shed energy down to c through radiation.

You're speaking of C through the medium, correct? Not absolute C. My understanding of Cherenkov radiation is that it is caused by a charged particle moving through a medium faster than a photon is able to, and those particle exicite whatever molecules are in the medium, pushing them above ground-state. The radiation is caused when the molecules fall back to ground-state. Correct?

[Arathena]

Correct, Embar. However, there must be energy transfer from the high-speed particle to the surrounding medium, which occurs by the interaction of the orbiting(moving) electrons and the magnetic field generated by the motion of the high-speed particle. The overall changes, enmasse, can be thought of as a distortion of the localized electromagnetic field of the molecules, which, upon the emission of photons by the excited electrons, relaxes back to 'ground' state - The high speed particle has effectively exerted a force on the sum total of surrounding, charged, subatomic particles, which in accordance with Mr. Newton, exert an equal and opposite force (and thus the deceleration) on the high speed charge, until such time as it is below c(medium) and 'classical' condensed matter physics takes over.

[Riggen]

Scissors aside, the most interesting FTL scenario that I've ever heard of involves a lighthouse and a bit of basic calculus. It demonstrates that mathmatically at least, the sweep of the light beam beyond a certain distance exceeds C. Obviously in this scenario no part of the beam *actually* travels faster than C, but it's still an interesting diversion.

[Embar Angylwrath]

Riggen,

The misconcpetion there is that the "beam" of light is treated as a static object, like a spoke in a wheel. But that's not the case. A beam of light is a flow of photons, like water out of a hose. If you had 360 observers standing in a circle 100 miles from the lighthouse, and 100 billion trillion trillion trillion miles from lighthouse, all taking measurements, they all would report the exact same velocity of light.

[Arathena]

There's something very fishy about that example, Riggen, but I'm not going to write it off in quite the same manner as Embar at the moment. I /suspect/ that there's a Lorentz contraction issue with the example, but I can't remember my relativity well enough at the moment. If the urge strikes, I'll take a look at the most simple case, the infinite length beam, and see where it resolves - Any circular motion using one end of the infinite beam should cause literally infinite motion on the other end, which means the correct equations should reduce to either infinity, zero, or possibly i somewhere along the line.

[Ddrak]

The issue is that the endpoint of the beam is actually travelling faster than light and there's no relativistic problem with it because that endpoint cannot result in information travelling from one point it passes through to another. Information is strictly travelling from the light emitter to each point.

Simply speaking, you can construct a frame of reference that is moving faster than light, but don't expect anything useful or sensible to come from it.

(At least that's my understanding)

Dd

[Embar Angylwrath]

Well....

Look at it this way. The "beam" is comprised of a bunch of photons. It's the individual photons in the beam that is measured, not the beam itself.

So, again, take two groups of people, each group consisting of 360 members, and place them in a circle surrounding the lighthouse, in a concentric cirlce pattern, with a person in the second group in a line directly behind, but about 20 trillion miles separated, from the person in the first group. Then turn on the light house beam. As a photon passes a person in the near circle, the photon will continue outward until it hits the second person, at the speed of light, no more, no less. The photon just passes the second person much much later than it passes the first person.

[Arathena]

Dd is right. And it's been an ass long time since I thought around relativity.

No massed particle can exist on the beam either, unless it is constructed of material of physical and dimension of proportion to (1/-i), and it must have a mass of proportion to (-i). Please bear in mind that the actual existance of this particle is neither provable, nor disprovable, but is mathematically permissble.

[Ddrak]

Ohh.... Tacyhons are fun!

Dd

[Riggen]

Oh sure, like I said it's obvious that no real part of the beam truly exceeds C. My presumption has always been that in such an event the beam of light acts sort of like the stream of water from a spinning hose. The stream "bends" and eventually breaks into smaller and smaller individual packets.

[SicTimMitchell]

Ohh.... Tacyhons are fun!

My understanding has been that tachyons are, well, bullshit. Has this changed?

[Arathena]

Tachyons, as I understand, are a pure mathematical construct. The empirically derived equations allow for their existance, however, they would not be able to interact with normal speed particles in any particularly meaningful fashion.

[maltheos]

Tachyons are neither proven nor disproven. They pretty much dont interact with normal matter, so verifying their existence is impossible.

[Arathena]

... You know, thinking about this. Any interaction between normal particles and tachyons would involve accelerations that are at mathematical right angles to reality. Perhaps this phenominon could quite possibly explain the thought processes of certain people? As their brains are bombarded with tachyons, their minds head off at a right angle to reality, lost in the 9th dimension...

[Embar Angylwrath]

The production of a tachyon would be easy... simply produce a particle with negative mass.