Troll Physics or Legit?

Hypothetically speaking, let's assume you had some kind of g-diffuser, that completely disengaged the pull of gravity around a perimeter. Let's say you had a spaceship.

Since there's no longer any drag on you, wouldn't you be able to accrue speed until you reached lightspeed and time-traveled without any further quibbling with the laws of physics?

My logic is assuming that since space is a vaccuum, that there won't be anything to slow the thrust of your ship once it's started moving thanks to Newton's third law.

Wait, does this g-diffuser negate the effect of outside gravity on all objects within the effected area. Or does it negate all gravity in the effected area including gravity caused by objects within the area?

OP here, I mean Newton's First Law.

I was just baiting.

Outside gravity working against the localizied area.

bump

Friction is a completely separate topic. The amount of energy required to accelerate depends on your current velocity (because your ~effective mass~ depends on your velocity). As you near c, the energy required approaches infinity.

Gravity isn't the only reason sending a rocket into space requires energy. The other reason is that accelerating an object requires energy, even in a vacuum.

So, no.

What if the rocket hurled towards something that was pre-emptively set ahead of it, or directed towards the trajectory of said object.

Let's say you aimed a rocket at the sun. As it's accelerating to the point of c, wouldn't the additional pull of the sun's gravity be able to send it over the edge at some point?

The sun is contributing to the finite force felt by the rocket, which still needs to be infinite to "reach" c.

The faster you going the more energy you need to spend to accelerate even more.

Even gravitational pull of something massive wont help you. Infinite amount of energy means basically infinite.

Why?

If you meant the other one, negating all gravity of stuff in the affected area, wouldn't that make it mass less? You could easily achieve FTL that way.

1) You would need infinite energy to get to speed of light
2) There are hydrogen atoms in space which would be significant at relativistic speeds
3) Even if you somehow could accelerate to speed of light it would take a long time unless you wanna get fucked up

I like getting fucked up though.

Yea, yea really- what if say, I DID wanna get fucked up? What about then?

How do you figure?

If you submerged the vehicle inside a giant tank of water, gravity or no, it would still have volume. Which means it has mass.

>wouldn't you be able to accrue speed until you reached lightspeed and time-traveled without any further quibbling with the laws of physics?
according to relativity no .

>let's assume you had some kind of g-diffuser, that completely disengaged the pull of gravity around a perimeter
If you have to start with something as stupid as that then it's not worth discussing

There is always a gravitational influence, no matter how weak. If you somehow left our local supercluster, there are still fields like the great attractor etc that you will veey slightly orbit. To say there is absolutely no gravitational influence on any object would imply a universal reference frame.

No.

Here's where you're confused- acceleration is actually not linear. Velocities don't really add - if you're going 30 mph down the highway, and accelerate another 30 mph, then the radar gun of the cop you pass won't actually *quite* read 60 mph (if it has unlimited accuracy). It's approximately linear at low speeds, but at higher and higher velocities, it works less and less well- if you are going at 0.4 c in some reference frame, and then go another 0.4 c faster, you are now going about 0.69 c.

Handwaving a bit, the reason why is that a velocity (where you move x amount of space in t amount of time) amounts to an *angle*, relative to the t axis of reference frame you're using to measure velocity against, in four-dimensional space-time. Because the time dimension isn't quite like the space dimensions (the distance formula is [math] d^2 = x^2 + y^2 + z^2 - t^2 [/math], which you'll note isn't quite Pythagorean), you have to use hyperbolic trig to work with these angles instead, which means they don't add like you'd expect. As a result, going faster and faster just gets you asymptotically close to a 45 degree angle, which corresponds to lightspeed. c is, effectively, infinite velocity - any massive object moving that fast would have infinite kinetic energy and infinite momentum, so you have to accelerate forever to get there, and if you were moving that fast you'd be able to traverse any distance in zero time from your point of view - but because of the nature of space-time, it only *looks* like it's 45 degrees of tilt away from the point of view of any other observer.

The velocity-addition law is as follows: If you are going at some velocity [math]v[/math], and add some additional velocity [math]u[/math], then your final velocity [math]s[/math] comes out to [eqn] s = \frac { v + u } { 1 + \frac { v u } { c^2 }[/eqn]. For v and u much less than c, [math] \frac { vu }{ c^2 }[/math] is about 0, and so this just turns into the ordinary s = v + u.

Whoops, missed a close-bracket in that last equation.

[eqn] s = \frac { v + u } { 1 + ( \frac { vu }{ c^2 } ) } [/eqn]

Thanks, this is very interesting.

Wow, I am indebted to you for this.

Howbeit, what if you could use the force of light triangulated at a particular location at 45 degree angles to boost an weightless object passing the unity point. I've read that it takes millions of years for light from the core of the sun to reach its surface, because the plasma it passes through is so dense. Let's say you had such an array of nuclear lasers.

What would happen if c were reached? Would an Einstein Ring have distorted the light around it since the mass of the object has reached near infinite density? Or would it not even affect it, since for the ship to surpass c it has to be moving faster than the lazers?