This may be a dummy question, but i couldn't find any dumb questions thread.
If you have a spacecraft in deep space, and it turns on its thrusters, the thrusters will start accelerating it. At what point will the accelerating stop and why?
Because i can't see any reason why it would stop accelerating, meaning you could reach light speed with a lighter if it had enough fuel, which is obviously retarded.
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The problem comes from having to have access to the fuel, either by bringing it or by scooping it. That, and the need for infinitely increasing amounts of fuel as you go faster.
I assume the difficulty is bringing enough fuel to accelerate to near light speed, not to mention the time it would take and how much fuel would be necessary to reduce speed enough to do anything useful. And bringing enough fuel to slow down means you need way more fuel to to deal with that extra weight.
This is basic relativity OP. As you accelerate more and more you can get asymptotically close to lightspeed, the closer you get to lightspeed, the more energy gets converted into mass, and less into speed.
Never really studied relativity but this is the gist of it I think.
Eventually you will exceed the speed of light and the space police will have to arrest you.
what energy gets converted into mass? is it the energy gained from an increase in momentum that then goes into increasing relative "mass" of the thing being accelerated rather than its velocity?
my brainlet intro to phys education tells me (not OP) that protons ejected from the sun begin traveling so fast they turn into "cosmic waves". This implies that their mass is lost and distributed into a wider area of space? isn't that contradictory to my above assumption? or are cosmic waves just wave-particles only their carrier is a fermion instead of a boson? but then why does the point-particle model fail at high velocities but not low velocities? Aren't subatomic particles already wavefunctions at low velocities?
All matter has wave-like properties, in accordance with the wavelength being equal to h/p (h being the Planck constant, p being momentum). As you can see, the wavelength is small at high velocities. In cosmic rays, this allows for much greater penetration, despite protons normally not being an issue for radiation shielding. They still retain their rest mass though.
In relativity, Newtonian physics is only acceptable at velocities much less than the speed of light (there is still error, but it is so small that it is negligable). To put it simply, it takes an infinite amount of kinetic energy for an object with non-zero rest mass to reach the speed of light. Velocity is unable to be added with simple addition, and kinetic energy adds to the mass of an object.
If you want to learn the equations for these operations:
en.wikipedia.org
you will stop accelerating when you run out of fuel.
kek
anyone have any insight on ionic thrusters?
what would be the problem if they were used in space travel?
Ironic thrusters consume fuel but provide no thrust.
Basic relativity says everyone's allowed to consider themselves to be stationary so the astronaut can happily accelerate forever and won't ever know how fast he's going.
Whilst they have very small thrust, they have a higher specific impulse than conventional thrusters, so they produce more thruster per mass of propellant.
ok, assuming fuel isn't an issue. will you eventually travel in the speed of light?
No. You can never reach the speed of light.
If you hit something it would obviously stop you, but assuming it's just a straight path, you would most likely be affected by a planets gravity at some point
No, it takes increasingly more and more energy to accelerate the next "bit" of speed in layman's terms, since only two people here seem to know what relativity implies. That being said, you could pack almost limitless amounts of energy into a moving object because it will take that much more energy to get it to be just a little infinitesimally faster. Mathematically speaking think of it as an integral or summation- getting to light speed requires INFINITE energy, which we don't have access to.
the less known thing is that if you would travel at the speed of light, you'd instantly(for you) be at your destination because the relativistic length contraction
The speed of light is relative, user. Even if you get going super duper fast and shine a light in front of your vehicle, that light will be moving away from you at the speed of light. You can't reach the speed of light. But no, you will not stop accelerating.