# how come our space travelling speed is limited?

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To sum up, I understand fully that fuel is an issue, I’m talking theoretical.

In space there is little to no resistance because of how few particles floating about. But if you were always running and engine, pushing matter out behind you, youd have a constant acceleration. So it seems like we should be able to travel near speed of light (combining this constant acceleration with abusing gravity for slingshot maneuvers). Yet people always say nothing can travel the speed of light.

In: Physics

Inertial mass increases with speed, though; so the faster an object moves, the greater its increase in mass. If you could find a theoretical way around that, then you’d be in Nobel prize territory.

As you get closer to the speed of light, the energy required to maintain constant acceleration increases exponentially… by the time you reached the edge of light speed you would be using up an infinite amount of energy – i.e. more fuel than is in the entire universe, not just in your rocket boosters.

Theoretically, given unlimited energy resources in propulsion, you can get as close to speed of light as you would like.

Realistically, even bridging Earth’s gravity well is very expensive, much less accelerate a probe to near light speed. It’s also an interesting consideration of what value is it to send a probe fast: communicating with Voyager (which is still very close to the solar system) is quite difficult, so sending any high-fidelity data would be a challenge on its own.

If you have shitload of fuel and shitload of times you could get to near speed of light. But as you go faster in relativistic speeds, it requires MORE and more fuel to move just a little bit faster.

An object’s mass will increase the closer it gets to the speed of light, and so the energy required to accelerate it does too. As an object reaches the speed of light it’s mass becomes infinite, and so does the energy required to accelerate it.

Or something like that, it’s been a while before I read this kind of stuff.