speed of light (part 2)

Originally posted by FabianFnas
And as adam warlock says: "You're not right at everything you're say." True, very true. If everybody writes only things that he/she is absolute certain of, then nothing much would be written.

If I could I would rec ya just for this.
Somebody please rec this guy. And I'm serious!

Originally posted by FabianFnas
If everybody writes only things that he/she is absolute certain of, then nothing much would be written.

But then how would we ever become certain of anything in the future? Through a lot of people who don't know for certain arguing, and quoting and experimenting etc., the group can become certain of other things in the future. There was a time when no human was certain of anything. Look at us now.

Originally posted by agryson
But then how would we ever become certain of anything in the future? Through a lot of people who don't know for certain arguing, and quoting and experimenting etc., the group can become certain of other things in the future. There was a time when no human was certain of anything. Look at us now.

I think that's what he's trying to say.
Do you think that it is a good idea to make a physics thread in general so we can discuss this and other issues related to physics?

would it be better to say, as yet, nothing has travelled the speed of light.... i really dont like the use of "it's impossible to travel the speed of light"... in saying that, you are implying not ever is it possible, even in 10, 100, or a million years...

Originally posted by eatmybishop
would it be better to say, as yet, nothing has travelled the speed of light.... i really dont like the use of "it's impossible to travel the speed of light"... in saying that, you are implying not ever is it possible, even in 10, 100, or a million years...

If I said something like "Perhaps we can't divide by zero today, but in the future we will be able to divide by zero", or "In the future I am sure that we will be able to print out all the decimals of pi!" people would say I'm crazy to have this opinion.

But I can say without blushing that "Someday in the future we will be start travelling!", or "Someday we will succeed with hydrogene fusion.", or Someday we will have a cure for cancer, AIDS, and Alzheimers!"

What is the difference between the two categories of statements? For one the first category of statements it is proven that it will not work. In the second category it is just a matter of time, money and will.

If we look at the statement of dividing by zero - in the equation E=mc2 you actually try to divide by zero if you put v=c. It's a fact. And therefore it will not work. You can't travel at the speed of light, it's impossible.

But, and this is interesting, if you put v>c you find yourself trying to get a square out of a negative number, it's just complex arithmetic, nothing more. Here I wont say that this is impossible. Perhaps in the future you can add an complex property to your own mass and voilà you have a superluminous velocity, and if you get rid of the imaginary property voilà you're back in normal velocities again.

I say - listen! - we know today how we can go to alpha Centauri and back in a years time! But we don't have the engine, or propellant to do it. Anyone knowing the theory of relativity knows it is possible. So star travelling is in theory already possible! And this not even necesary to go with light speed! Or worm holes, or tunneling or anything not yet known!

But I can say without blushing that "Someday in the future we will be start travelling!", or "Someday we will succeed with hydrogene fusion.", or Someday we will have a cure for cancer, AIDS, and Alzheimers!"

should be

But I can say without blushing that "Someday in the future we will be start travelling to the stars!", or "Someday we will succeed with hydrogene fusion.", or Someday we will have a cure for cancer, AIDS, and Alzheimers!"

Sorry for that mistake...

Originally posted by agryson
No, and actually, there's nothing to stop anything from travelling [b]at the speed of light, except for the enormous quantity of energy required. The actual thing is that nothing can travel faster, without its mass converting to energy (which doesn't travel faster than light either)[/b]

If light is bent by a gravitational field, did it accelerate?

Originally posted by AThousandYoung
If light is bent by a gravitational field, did it accelerate?

In general relativity acceleration and graviity are equivalent so the answer is yes.

Does electricity travel at the speed of light?

Originally posted by smw6869
Does electricity travel at the speed of light?

No, electricity is quite slow.
However, the electrical impulse is rather fast, but not as fast as light.

Originally posted by FabianFnas
I say - listen! - we know today how we can go to alpha Centauri and back in a years time! But we don't have the engine, or propellant to do it. Anyone knowing the theory of relativity knows it is possible. So star travelling is in theory already possible! And this not even necesary to go with light speed!

Considering that Alpha Centauri is 4.3 light-years away, to get there and back in a year means that you'd have to travel at more than 8 times the speed of light. So I'm not sure what you're on about here.

Edit: Unless of course you mean a year for the people travelling. This could be possible with a sufficient speed still under the speed of light, but it would have to be near light-speed in order to obtain the time-dilation effects, and no matter how quick it seemed to the people on board the craft, it would still be almost 9 years Earth time before you got back, not including any time spent there.

Originally posted by Suzianne
Considering that Alpha Centauri is 4.3 light-years away, to get there and back in a year means that you'd have to travel at more than 8 times the speed of light. So I'm not sure what you're on about here.

Edit: Unless of course you mean a year for the people travelling. This could be possible with a sufficient speed still under the speed of light, but ...[text shortened]... d still be almost 9 years Earth time before you got back, not including any time spent there.

Exactly what I mean.

To go there and back can't go under 4.3 times two years earth time. But onboard the ship it can take a lot less. If you are fast enough you can travel around the galaxy in (near to) no time. But you will never meet your friends back here ever again, long gone. What creatures you will meet, no one knows, yet.