Our current space tech so depressing

[Frank]

Inverse square law. You need lots of power.

Inverse square law only applies is you broadcast in all directions. If you collimate the transmissions as a beam the fall-off of intensity with distance is much less rapid than 1/r^2 (which is why communications dishes are generally parabolic).

Yes, I know. But even then, the dispersion is huge over those distances.

 

[Frank]

Would that energy dissipate through the entire vehicle or simply give the grain of sand extreme penetration and create a tiny hole through a lot of the vehicle...

I suppose you could posit a moderately sized asteroid at the front as a shield.

Or rather, use an entire moon as your space ship. They can take it.

 

[London Geezer]

Would that energy dissipate through the entire vehicle or simply give the grain of sand extreme penetration and create a tiny hole through a lot of the vehicle...

I suppose you could posit a moderately sized asteroid at the front as a shield.

Or rather, use an entire moon as your space ship. They can take it.

Heh, try getting that to accellerate to the speed of light...

Another thing, if we ever go at light speed then how would we pilot it at such great speed? Bec'se reaction time would be in nano seconds? Otherwise BOOM!

That just reminded me of Space Balls

Colonel Sandurz: Prepare ship for light speed!
Dark Helmet: No, no, no, light speed is too slow.
Colonel Sandurz: Light speed too slow?
Dark Helmet: Yes, we're gonna have to go right to.....ludicrous speed!
Crew: Huh?? Huh??
Colonel Sandurz: Ludicrous speed? Sir, we've never gone that fast before. I don't know if the ship can take it!
Dark Helmet: What's the matter, Colonel Sandurz? Chicken?

 

[Frank]

Heh, try getting that to accellerate to the speed of light...

Just a question of scale, is all.

 

[pax]

Hhe Id be happy with 50% the speed of light and I suppose for safety's sake being the trip will cover so much distance a 3-400 meter wide asteroid would do to avoid the impacts of grains of sand? Whats 2 tons of tnt of energy in space with little gravity or gas atmosphere to send shockwaves through?... That and hydrogen being the most common things the ship would impact on its way to the nearest stars.

Im not sure of the odds of hitting something bigger... but the voyager and pioneer probes have covered a good distance will little problem.
8)

 

[London Geezer]

Well Universe is VERY empty and dull so there shouldn't be too many problems. Big things might just be detected and somehow avoided or shot down.


Now, what i never really understood... If i shoot a laser forward, towards the direction i'm going, and i'm going at the speed of light, does the laser... work? U know what i mean? It can't go forwards any faster than the ship, so it can't work...
Same thing backward, if we shoot it the other way, will it "stay still" so to speak?

 

[sytaylor]

Now, what i never really understood... If i shoot a laser forward, towards the direction i'm going, and i'm going at the speed of light, does the laser... work? U know what i mean? It can't go forwards any faster than the ship, so it can't work...
Same thing backward, if we shoot it the other way, will it "stay still" so to speak?

Special Relativity (IIRC) should describe what happens when you get close to the limit, I'll do some digging, but there is an alarm bell ringing in my head thatsa saying "OOO I know this one"

 

[sytaylor]

et voila

"Others things which can go faster than the speed of light include the spot of a laser which is pointed at the surface of the moon. Given that the distance to the moon is 385,000 km try working out the speed of the spot if you wave the laser at a gentle speed. You might also like to think about a wave arriving obliquely at a long straight beach. How fast can the point at which the wave is breaking travel along the beach?"

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html

Took a little bit of bookmark digging but I got there.

 

[Frank]

Now, what i never really understood... If i shoot a laser forward, towards the direction i'm going, and i'm going at the speed of light, does the laser... work? U know what i mean? It can't go forwards any faster than the ship, so it can't work...
Same thing backward, if we shoot it the other way, will it "stay still" so to speak?

The speed of light is always the same, locally. Just look at it from the perspective of your ship being stationary in it's own (large) space bubble. Subjectively, it would be the same thing.

In the same way, the relative speed between two objects or particles won't get above C either, even if that means that time has to be adjusted locally.

 

[sytaylor]

Indeed, in the example I gave the laser is observed from a third person perspective and appears to be moving faster than light.

 

[nutball]

Now, what i never really understood... If i shoot a laser forward, towards the direction i'm going, and i'm going at the speed of light, does the laser... work? U know what i mean? It can't go forwards any faster than the ship, so it can't work...
Same thing backward, if we shoot it the other way, will it "stay still" so to speak?

Oh boy, it's been fifteen years since I did special rel. IIRC it leaves the ship at the speed of light with respect to the ship, so yes it does go forward. From the point of view of an external observer, neither the ship nor the laser exceed the speed of light.

 

[nutball]

"Others things which can go faster than the speed of light include the spot of a laser which is pointed at the surface of the moon. Given that the distance to the moon is 385,000 km try working out the speed of the spot if you wave the laser at a gentle speed. You might also like to think about a wave arriving obliquely at a long straight beach. How fast can the point at which the wave is breaking travel along the beach?"

That's not the same thing, in that example nothing (no information) is travelling faster than the speed of light. It's the distinction between group velocity (which is constrained to be less than the speed of light) and phase velocity (which isn't).

 

[London Geezer]

Now, what i never really understood... If i shoot a laser forward, towards the direction i'm going, and i'm going at the speed of light, does the laser... work? U know what i mean? It can't go forwards any faster than the ship, so it can't work...
Same thing backward, if we shoot it the other way, will it "stay still" so to speak?

Oh boy, it's been fifteen years since I did special rel. IIRC it leaves the ship at the speed of light with respect to the ship, so yes it does go forward. From the point of view of an external observer, neither the ship nor the laser exceed the speed of light.

.... which means...?

If i'm on the ship, i can shoot the asteroid in front of me down? that would mean that the laser is travelling faster than the speed of light relative to the asteroid...? Poor asteroid that's cheating.

See that's what i can't get me head round.

 

[sytaylor]

"Others things which can go faster than the speed of light include the spot of a laser which is pointed at the surface of the moon. Given that the distance to the moon is 385,000 km try working out the speed of the spot if you wave the laser at a gentle speed. You might also like to think about a wave arriving obliquely at a long straight beach. How fast can the point at which the wave is breaking travel along the beach?"

That's not the same thing, in that example nothing (no information) is travelling faster than the speed of light. It's the distinction between group velocity (which is constrained to be less than the speed of light) and phase velocity (which isn't).

I saw laser and got confused

 

[nutball]

.... which means...?

If i'm on the ship, i can shoot the asteroid in front of me down?

In principle, if you're a good shot, yes.

that would mean that the laser is travelling faster than the speed of light...?

No.

See that's what i can't get me head round.

Yeah, it is a bit of a mind-fuck isn't it? The point is what you're talking about are relative speeds, the speed of this relative to that. When talking about relative speeds you have to define a frame of reference. What relativity says is that when you transform between reference frames, the transformation is non-linear. It all washes out in the maths.

So if you're moving away from me at half the speed of light, and you shoot your laser away from me, you would see the photons moving away from you at the speed of light. I would also see those same photons moving away from me at the speed of light *not* 1.5x the speed of light.

Basically if you are measuring a speed relative to yourself, then trying to calculate the speed relative to myself, you are transforming between reference frames, and at speeds close to that of light the normal rules of addition of velocities that you're used to no longer hold.

 

[London Geezer]

So if you're moving away from me at half the speed of light, and you shoot your laser away from me, you would see the photons moving away from you at the speed of light. I would also see those same photons moving away from me at the speed of light *not* 1.5x the speed of light.

That's my point - the point being i dont get it.

Right. i'm 900000km away from the asteroid. Keeping still.

If i shoot a laser to the asteroid, i'll hit it in 3 seconds. Good.

Now, if i'm travelling at the speed of light towards the target- let's keep it simple and have it at 300000km/s - will i still hit the asteroid in 3 seconds? That would make sense for the asteroid but not for me, going at Ludicrous Speed.

But then if i'm travelling at the speed of light, it won't even be 3 seconds for me cause time would stop... only for the... AAAAAAARRRRRGGGGGGGHHHHHH!!!!!!!!!!

 

[Frank]

That's my point - the point being i dont get it.

Right. i'm 900000km away from the asteroid. Keeping still.

If i shoot a laser to the asteroid, i'll hit it in 3 seconds. Good.

Now, if i'm travelling at the speed of light towards the target- let's keep it simple and have it at 300000km/s - will i still hit the asteroid in 3 seconds? That would make sense for the asteroid but not for me, going at Ludicrous Speed.

But then if i'm travelling at the speed of light, it won't even be 3 seconds for me cause time would stop... only for the... AAAAAAARRRRRGGGGGGGHHHHHH!!!!!!!!!!

Just think of it like this: time will slow down for you and all other observers until things don't exceed the speed of light anymore.

That's not correct, but works well in relation to space travel at ludicrous speed.

 

[London Geezer]

That's my point - the point being i dont get it.

Right. i'm 900000km away from the asteroid. Keeping still.

If i shoot a laser to the asteroid, i'll hit it in 3 seconds. Good.

Now, if i'm travelling at the speed of light towards the target- let's keep it simple and have it at 300000km/s - will i still hit the asteroid in 3 seconds? That would make sense for the asteroid but not for me, going at Ludicrous Speed.

But then if i'm travelling at the speed of light, it won't even be 3 seconds for me cause time would stop... only for the... AAAAAAARRRRRGGGGGGGHHHHHH!!!!!!!!!!

Just think of it like this: time will slow down for you and all other observers until things don't exceed the speed of light anymore.

That's not correct, but works well in relation to space travel at ludicrous speed.

But Ludicrous speed is faster than light so that means time goes backwards...?

PIZZA: Well, if it isn't Lone Starr, and his side kick, Puke.

BARF: That's Barf.

PIZZA: Barf, Puke, whatever. Where's my money?

HELMET: Who made that man a gunner?

MAJOR: I did, sir. He's my cousin.

HELMET: Who is he?

SANDURZ: He's an Asshole, sir.

HELMET: I know that. What's his name?

SANDURZ: That is his name, sir. Asshole, Major Asshole.

HELMET: And his cousin?

SANDURZ: He's an Asshole, too, sir. Gunner's-mate, 1st Class, Philip Asshole.

HELMET: How many Assholes we got on this ship, anyhow?

ALL: Yo!

HELMET: I knew it. I'm surrounded by Assholes. Keep firing, Assholes.

 

[digitalwanderer]

Is the speed of light faster than the speed of thought? :|

 

[BlueTsunami]

Is the speed of light faster than the speed of thought? :|

Puzzling question isn't it. I would think that it would depend on how fast pulses run through our nerves....but theres so many black box factor with our minds..who knows...all I know is that our minds must be equiped with alot of bandwith...

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