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No, this will never happen, because traveling at relativistic speeds is not the same as traveling back in time.Tomlidich wrote:at some point, it gains enough speed to fall within the theory of relativity, transporting the ball to a time when the portal was not on the floor.
gmalivuk wrote:No, this will never happen, because traveling at relativistic speeds is not the same as traveling back in time.Tomlidich wrote:at some point, it gains enough speed to fall within the theory of relativity, transporting the ball to a time when the portal was not on the floor.
Waffles to space = 100% pure WIN.
gmalivuk wrote:It's pointless to wonder about what relativity says in a magical system where we have a constant infinite gravitational field.
AvatarIII wrote:i do wonder, personally, what stops an object from surpassing the speed of light if the force supplying acceleration is gravity for example,
on earth an object will accelerate at 9.81ms^{-2}, now in normal circumstances, the exertion of gravity wouldn't have effects on an object for long enough to build up relativistic speeds, but in the portal scenario it would have infinite time.
i was under the impression that things could not accelerate above the speed of light because whilst within the time frame of an object it would be accelerating constantly, from an outside time frame it would be reducing in acceleration due to relativistic effects, but if the cause of the acceleration was not under these effects, would the bowling ball constantly feel 9.81ms^{-2}, or would earth gravity in the normal time frame continue to accelerate the ball at 9.81ms^{-2}?
Philip Gibbs et al wrote:First of all we need to be clear what we mean by continuous acceleration at 1g. The acceleration of the rocket must be measured at any given instant in a non-accelerating frame of reference travelling at the same instantaneous speed as the rocket (see relativity FAQ on accelerating clocks).
This acceleration will be denoted by a.
The proper time as measured by the crew of the rocket (i.e. how much they age) will be denoted by T, and the time as measured in the non-accelerating frame of reference in which they started (e.g. Earth) will be denoted by t. We assume that the stars are essentially at rest in this frame.
The distance covered as measured in this frame of reference will be denoted by d and the final speed v.
The time dilation or length contraction factor at any instant is the gamma factor γ.
The relativistic equations for a rocket with constant positive acceleration a > 0 are the following. First, define the hyperbolic trigonometric functions sh, ch, and th (also known as sinh, cosh, and tanh):sh x = (e^{x} - e-^{x})/2
Using these, the rocket equations are
ch x = (e^{x} + e-^{x})/2
th x = sh x/ch xt = (c/a) sh(aT/c) = sqrt[(d/c)^{2} + 2d/a]
These equations are valid in any consistent system of units such as seconds for time, metres for distance, metres per second for speeds and metres per second squared for accelerations. In these units c = 3 × 10^{8} m/s (approx). To do some example calculations it is easier to use units of years for time and light years for distance. Then c = 1 lyr/yr and g = 1.03 lyr/yr^{2}. Here are some typical answers for a = 1g.
d = (c^{2}/a) [ch(aT/c) - 1] = (c^{2}/a) (sqrt[1 + (at/c)^{2}] - 1)
v = c th(aT/c) = at / sqrt[1 + (at/c)^{2}]
T = (c/a) sh-1(at/c) = (c/a) ch-1 [ad/c^{2} + 1]
γ = ch(aT/c) = sqrt[1 + (at/c)^{2}] = ad/c^{2} + 1
- Code: Select all
T t d v γ
1 year 1.19 yrs 0.56 lyrs 0.77c 1.58
2 3.75 2.90 0.97 3.99
5 83.7 82.7 0.99993 86.2
8 1,840 1,839 0.9999998 1,895
12 113,243 113,242 0.99999999996 116,641
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EvanED wrote:be aware that when most people say "regular expression" they really mean "something that is almost, but not quite, entirely unlike a regular expression"
Avenger_7 wrote:You are entitled to your opinion though. Even though it's wrong.
KrO2 wrote:That's clever. You can get around the limited delta-v by placing another portal on the outside of the ship, assuming you can switch which one it comes out of without timing problems, so there might be an upper limit on how fast the rod can move. But once the rod gets moving to wherever you're not comfortable accelerating it any more, you can just have it railgun out the back of your ship (or whatever direction you want, if you want to hit something with it) and just start again with another rod.
Waffles to space = 100% pure WIN.
idobox wrote:Also the fact that the portals seem to create energy (the kinetic energy given to the ball comes form?), makes it easy to get absurd results.
Magnanimous wrote:(fuck the macrons)
eSOANEM wrote:idobox wrote:Also the fact that the portals seem to create energy (the kinetic energy given to the ball comes form?), makes it easy to get absurd results.
Portals can be made to conserve energy (and, in certain senses, momentum), you just need to allow it to steal energy from its surroundings when it is giving an object extra energy and dump gamma rays (which portals are known to emit) when it is losing energy. As for momentum, you just take the area immediately local to the portals, join them up (remembering that portals have a specific orientation) and then conserving momentum in this portal-space.
Of course, this makes portals very powerful weapons; not only can they easily accelerate relativistic kill vehicles or other projectiles, they can also be used to dump gamma rays by portalling a surface inside a black hole and the other one near your enemy.
gmalivuk wrote:Yeah, I think it's the stepping disks in Larry Niven's Known Space that can only handle up to a certain limited momentum difference, and get really hot and have to cool down if there's a lot of extra energy that needs bleeding off.
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