simulated meteor strike

Lamp

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Svartmetall said:
Don't nit-pick :p

But yes, of course, you're right - what we see today is how it looked (in the case of something 7,500 light years away) 7,500 years ago. In terms of how it affects us, since no effect travels faster than light, it's the same thing in the end.

Actually, - and sorry to nit pick again - there's an effect called Cherenkov Radiation (see in nuclear reactors) which is emitted as a result of electrons travelling FASTER THAN THE SPEED OF LIGHT (sorry - not shouting - just emphasising) which is visible to humans as a blue glow:

TrigaReactorCore.jpeg
 

old.Tohtori

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Svartmetall said:
(although mainly just stuff like satellites etc, due to the massive amounts of gamma rays produced by a supernova).

WOHOO!! We're all going to be a f*cking unstoppable race of Hulks! :worthy:
 

Svartmetall

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Lamp said:
FASTER THAN THE SPEED OF LIGHT
Yes and no. They're travelling faster than the speed of light in the medium in whcih the Cherenkov radiation is emitted, in this case in an insulator where the speed of light may be as low as ~0.75C - so while they're going faster than the local speed of light, they're not going faster than the classical C constant in a vacuum, 299,792,458 metres/second.
 

chretien

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Lamp said:
Actually, - and sorry to nit pick again - there's an effect called Cherenkov Radiation (see in nuclear reactors) which is emitted as a result of electrons travelling FASTER THAN THE SPEED OF LIGHT (sorry - not shouting - just emphasising) which is visible to humans as a blue glow:
That's not entirely true. Cherenkov Radiation travels faster than the phase velocity of light (i.e. the speed of the waveform) rather than the group velocity (which is the actual speed of the photons and therefore the information carrying particles). Also it's only 'faster than light' when the speed of light is reduced by being made to travel through a dampening medium.

It's possible for waveforms to travel faster than light even in a vacuum but that's irrelevant as a waveform can't carry any information by itself. Particles with mass (such as electrons) cannot travel faster than light.
 

chretien

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My reply was phase dampened by my boss snooping around my desk. The information carrying particles in my post are actually faster than the ones in yours.
 

Lamp

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chretien said:
My reply was phase dampened by my boss snooping around my desk. The information carrying particles in my post are actually faster than the ones in yours.

ROFLMAO

Repped. That cracked me up
 

Svartmetall

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I dispute that theory, sir! In fact the equation


2{3/x}/4nt-6{0.5*t*}


where x is the density of one's boss/medium and t is the space/time value of C in the given area clearly demonstrates that it has nothing to with the velocity of your particles, but merely shows that your boss is unusually dense.
 

Lamp

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Is Faster Than Light Travel or Communication Possible?

Take the following wave equation:

d2u d2u
-- - c2 -- + w2 u = 0
dt2 dx2

This has solutions of the form:


u = A cos( ax - bt )

c2 a2 - b2 + w2 = 0

These solutions are sine waves propagating with a speed,


v = b/a = sqrt(c2 + (w/a)2)

But this is faster than light, so is this the equation for a tachyon field? No it is the usual relativistic equation for an ordinary massive scalar particle!

The paradox is resolved by distinguishing this velocity which is known as the phase velocity vph from another velocity known as the group velocity vgr which is given by,


vgr = c / vph

If a wave solution has a frequency dispersion it will take the form of a wave packet which travels at the group velocity which is less than c. Only its wave trains travel at the phase velocity. It is only possible to send information with such a wave equation at the group velocity so the phase velocity is yet another example of a speed faster than light which cannot carry a message.
 

Neffneff

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nerf, ofc you can make things travel faster than light, unfortunately time itself is irritable and forbids it, making neccessary adjustments to itself to prevent such things.

all we need to do is ask time nicely to behave itself, or, find a way around it. :)
 

Lamp

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Isn't outer space a vacuum ?

When Einstein wrote down his postulates for special relativity, he did not include the statement that you cannot travel faster than light. There is a misconception that it is possible to derive it as a consequence of the postulates he did give. Incidentally, it was Henri Poincare who said "Perhaps we must construct a new mechanics, . . . in which the speed of light would become an impassable limit." That was in an address to the International Congress of Arts and Science in 1904 before Einstein announced special relativity in 1905.

It is a consequence of relativity that the energy of a particle of rest mass m moving with speed v is given by


E = mc2/sqrt(1 - v2/c2)

As the speed approaches the speed of light the energy approaches infinity. Hence is should be impossible to accelerate an object with rest mass to the speed of light and particles with zero rest mass must always go at exactly the speed of light otherwise they would have no energy. This is sometimes called the "light speed barrier" but it is very different from the "sound speed barrier". As an aircraft approaches the speed of sound it starts to feel pressure waves which indicate that it is getting close. With some more thrust it can pass through. As the light speed barrier is approached (in a perfect vacuum) there is no such effect according to relativity. Moving at 0.99999c is just like standing still with everything rushing past you at -0.99999c. Particles are routinely pushed to these speeds in accelerators so the theory is well established. Trying to get to the speed of light in this way is like trying to get to the pot of gold at the end of a rainbow.

This explains why it is not possible to exceed the speed of light by ordinary mechanical means, however, it does not in itself rule out FTL travel. It is really just one way in which things cannot be made to go faster than light rather than a proof that there is no way to do it. Particles are known to decay instantly into other particles which fly off at high speed. It is not necessary to think in terms of the particles having been accelerated so how could we say that they could not go faster than light? What about the possibility of particles which might have always been going faster than light and which might be used to send information if they can be detected and deflected without ever slowing down to less than the speed of light? Even if such particles don't exist there may be ways of moving matter from A to B, faster than light can get there by the usual root, but without anything having to go at a FTL speed locally.
 

razeredge

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ah dont worry will never happen, if i'm wrong may i be crushed from above somehow
 

Lamp

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I don't want to start a panic or anything, but the world will end next Tuesday at 8:53am
 

Darzil

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Lamp said:
I don't want to start a panic or anything, but the world will end next Tuesday at 8:53am

Darn. Can't it come a bit earlier so I don't have to get up ?

Darzil
 

Lamp

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!!!

SoulFly said:
http://www.rense.com/general72/size.htm

I love that site, it makes me feel so tiny :D

The last slide on that site contains the star Antares, which is 510 times the diameter of our sun.

This is dwarfed by the star W Cephei, which is 1900 times our sun's diameter If it replaced the Sun in our solar system it would extend to the orbit of Saturn !!! It is 315,000 times as luminous than our Sun.

The surface temperature of our Sun is a mere 5,500 C (9,932 F)

The surface temperature of Sirius B is 31,726 C (57,140 F)

The temperature 17 meters from the Hiroshima nuclear bomb was 300,000 C (540,000 F)
 

MesS°

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Lamp said:
The last slide on that site contains the star Antares, which is 510 times the diameter of our sun.

This is dwarfed by the star W Cephei, which is 1900 times our sun's diameter If it replaced the Sun in our solar system it would extend to the orbit of Saturn !!! It is 315,000 times as luminous than our Sun.

The surface temperature of our Sun is a mere 5,500 C (9,932 F)

The surface temperature of Sirius B is 31,726 C (57,140 F)

The temperature 17 meters from the Hiroshima nuclear bomb was 300,000 C (540,000 F)

Its 30 C outside atm. We are getting there....
 

Ctuchik

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if something like that acually DOES hit, i'm gonna pray to god i'm gonna be smack down in the middle of the impact so i'l die fast and painless :)
 

ilaya

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whats those things called out in deep space that are spinning around occasionally sending out enough energy to destroy entire solar systems?
 

Raven

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pulsars or quasars (sp?) or something i think
 

Dukat

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Svartmetall said:
astronomically speaking....

I knew trouble was coming as soon as I saw this! :eek:

and btw...

13db986.jpg


Antares isnt fat, its just big boned! :D
 

old.Tohtori

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Well another funny "destroy the world!" thing i heard is these spaceclouds(yeah i'm real down with the scientist lingo) that freeze everything in their path.

Earth was due passing one of these evidently ages ago.

HAve to look it up in more detail.
 

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