Thread: October 14, First Contact

Originally Posted by drewmandan

I am smarter than you.



The ergosphere of a spinning black hole is the region of space around the black hole in which frame dragging causes spacetime to move at or above the speed of light, in laymen's terms. A ship in such a region would be traveling backwards in time with respect to flat space.

The singularity of a spinning black hole is a torus in a sense, but you can't picture it.

Special relativity basically says that you can't travel anywhere faster than light would. So if you took a round trip to a star 100 ly away, you can't possibly arrive back on Earth sooner than 200 years after you left. But if, on the way back, you swung around a spinning black hole and traveled a couple hundred years back in time, that would allow you to arrive just after or even before you left. For the sake of continuity, it would make sense to arrive after the time you left.



Ships can travel arbitrarily close to the speed of light, and I still don't see what sound has to do with this.

This is only true when the space ships you are talking about have access to an arbitrarily large amount of energy. As the ship accelerated towards the speed of light, it would take exponentially larger amounts of energy to continually accelerate.

Originally Posted by drewmandan

Your comment about mass is wrong. Momentum approaches infinity, not mass. In classical physics, momentum is just the product of mass and velocity, but in both special relativity and quantum physics, momentum is a fundamental property of an object, just like mass. In fact, the mass of a moving object is invariant, meaning it never changes.

Actually, Momentum remains constant in any closed system, but the mass does approach infinity as the object approaches the speed of light. If you want me to explain relative momentum to you I will, but it is a bit indepth.

Originally Posted by drewmandan

God, I hate having to correct people that haven't taken university courses on relativity, like me.

I hate having to correct bratty little kids who think taking a first year physics class makes them the smartest person on the internet.

Originally Posted by Xaqaria

This is only true when the space ships you are talking about have access to an arbitrarily large amount of energy. As the ship accelerated towards the speed of light, it would take exponentially larger amounts of energy to continually accelerate.

My point is that to reach any arbitrary fraction of c requires a finite amount of energy. Getting to 0.9999c requires certain energy, and getting to 0.999999c requires more, but also a certain amount. Now where you draw the line between "a lot" and "too much" depends on your power source, ship design, etc.

Originally Posted by Xaqaria

Actually, Momentum remains constant in any closed system,

Yes, but then you must include the momentum of the reaction mass used to reach said relativistic velocity. The momentum of the ship alone is then not a closed system and does increase.

Originally Posted by Xaqaria

but the mass does approach infinity as the object approaches the speed of light. If you want me to explain relative momentum to you I will, but it is a bit indepth.

No, mass is invariant. Momentum is given by gamma_u*m*v, where gamma_u is the Lorentz factor, m is invariant mass, and v is velocity.

Originally Posted by Xaqaria

I hate having to correct bratty little kids who think taking a first year physics class makes them the smartest person on the internet.

All your points were incorrect.
I suggest you educate yourself, if you can:
http://en.wikipedia.org/wiki/Special_relativity

Originally Posted by drewmandan

My point is that to reach any arbitrary fraction of c requires a finite amount of energy. Getting to 0.9999c requires certain energy, and getting to 0.999999c requires more, but also a certain amount. Now where you draw the line between "a lot" and "too much" depends on your power source, ship design, etc.




Yes, but then you must include the momentum of the reaction mass used to reach said relativistic velocity. The momentum of the ship alone is then not a closed system and does increase.



No, mass is invariant. Momentum is given by gamma_u*m*v, where gamma_u is the Lorentz factor, m is invariant mass, and v is velocity.



All your points were incorrect.
I suggest you educate yourself, if you can:

Mass in the equation you are quoting isn't defined as 'invariant mass', it is defined as rest mass.

None of my points were incorrect, and I've had too much education on the subject for wikipedia to be any use to me. I suggest you try looking for better reference besides open source free internet websites.