Physics Question

Actually idMonster3000, it's spelt "Facetious".

And is the other word "antidisestablishmentarianism"? Just kidding. Did prove one thing though; I was told by my History teacher at school that I would never use the word "antidisestablishmentarianism" in a sentence, yet I've just used the word "antidisestablishmentarianism" three times in the same paragraph; ha! :P
 
idMonster,

forgive my ignorance, but.....

as i understand it, to accuratly measure the speed that another body is moving you need to know for definate either one of two things.

1. you need to know for 100% certain that you are stationary ( or does that make you a pencil?)
or
2. You need to know the speed that you are travelling in relation to the oblect you wish to measure.
Click to expand...

Neither choice is exactly correct.

According to the Special Theory of Relativity there is no absolute state of rest. You are either moving or at rest with respect to some other object.

So, you measure speed and velocity by "looking out the window" of your car, plane or space ship and looking at how quickly other objects that you can see move past you.

But this makes good common sense. Let's say you are coasting alongside another space ship. You can't see any closeby planets or moons - nothing to use to judge your velocity against..

But the stars stay relatively fixed and you conclude that your two ships are stopped.

Two other space ships, also in tandem, pass by you after approaching you from your 12 o'clock position. You conclude that they were moving at "X" meters/sec. But the personnel on the other two ships can correctly come to the same conclusion that you came to. They are the ships at rest and it is your ships that are moving at "X" meters/sec.

If you then accelerate your ship at 1g, close off all exterior views, insulate it so that no noise can be heard that give hints about the fact that its a space ship and given that the "floor" of the space ship that you are standing on is sufficiently small (a couple of kilometers wide at most) then there is no possible experiment that you can perform that would let you decide whether you are in a 1g gravitational field or a 1g acceleration on the space ship.

That's the principle of equivelance in Special Relativity.

So you have two STR issues:

1. There is no absolute state of rest or motion. Motion is meaasured relative to something else.

2. You have gravitation and acceleration. They are not the same but they are equal in their effect. If you are prevented from having external clues about the situation you cannot design an experiment inside your space ship (aka laboratory) that can differentiate between the two.
 
bogz,

Well I say it's unlikely you "turn into" photons as you come into contact with an equal mass of antimatter - you and the anti-mass would mutually annihilate, releasing massive amounts of energy (E=mc^2). The energy causes photons to pop into existance as it speeds through space. But I could be wrong...
Click to expand...

You're correct. I was making a bit of a joke.

You're mass that actually came into contact with anti-matter would be annihilated (they would mutually annihilate) and radiate its energy as photons - from IR through hard gamma radiation or even cosmic radiation. The vast majority would be the very high energy photons.

In reality it would be almost impossible for all of your mass to mutually annihilate with the anti-matter. The force of the initial explosion would accelerate the left over matter away from the center of the blast and the matter/anti-matter reaction would come to a stop.

That's a good thing. If you and your anti-matter twin mutually annihilated all ~250kg of combined mass somewhere on Earth oure planet would suffer an "interesting" event.

A 1 megaton nuclear reaction consumes ~.047 grams of mass. Therefore, the energy released by you and your anti-twin would be ~5,319,150 megatons!

"Titor's World War III" would be a snail fart by comparison.

At least in his story half of the population survives. In your twin annihilation scenario no one survives. The planet itself would take two huge hits: One at the blast site and another on the opposite side of the planet (like the Weird Terrain on Mercury - the wrinkled surface of Mercury caused by a meteor strike in the Caloris Basin.. The Weird Terrain is exactly 180 degrees around the planet from the Caloris Basin. It was caused by extremely high energy seismic waves that radiated away from a huge meteor strike in the Caloris Basin.).

/ttiforum/images/graemlins/smile.gif
 
Hmm ok now I have to ask - We can't collect anti-matter in large quantities right? And hopefully never will?
 
bogz,

Hmm ok now I have to ask - We can't collect anti-matter in large quantities right? And hopefully never will?
Click to expand...

Correct. "We" can't colllect appreciable quantities of anti-matter.

That doesn't necessarily mean that some future evolution of humanity won't be able to do so and control a matter/anti-matter reaction.

Remember that in Star Trek the good star ship "Enterprise" exists some 400 years in our future. So it's is possible, at least in that context, that in four centuries mankind will have the ability to contain and successfully use that sort of engine.

Aside: In Star Trek it is an interesting misque re. the matter/anti-matter engines. In the real world they probably represent their "impulse" drive. Matter/Anti-matter reaction will not result in their system of "warp drive". Warp drive would require a Positive Matter/Negative Matter (aka Exotic matter) reaction where the "Exotic Matter" has a net energy of less than zero. Anti-matter has a net energy of greater than zero (positive energy).
 
Maybe their definition of anti-matter has changed to encompass "exotic matter".
 
[quote author=ussfletcher]It seems to me that "Spelt" is a very uncommon way to say or spell "spelled" in America anyway

[/quote]

No, well, kinda; "spelt" is the original spelling, but over time spoken language and the phonemes that it consists of become blurred, so that "spelt" is now "spelled" instead. Similarly with most other "-elt" and similar words, like smelt, wept, dreamt,...

At least the words "sleeped" and "keeped" do not yet exist though. /ttiforum/images/graemlins/smile.gif Given time, however, they will. So if significant temporal distances can someday be traversed, then we shall come across humans who speak what might as well be "alien" languages (at least to us). By that, I mean no more than a few centuries; could YOU make yourself understood in Shakespearean times?
 
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