Traveling through Space?

Question

If there is no gravity in space why is speed limited when traveling through outerspace?

Answer 1

Firstly in space there is gravity. It is everywhere and just because we are not pulled toward something does not mean we aren't affected by its gravity.

A spaceship in space is still powered by rockets for acceleration and deceleration. These work by thrust - chucking something out the back to move forwards. The speed you can go in space is limited to the amount of stuff you have to chuck out the back and how fast you can do it, in this case rocket fuel.

Answer 2

Hi Cleetus -

The problem is not with gravity or the lack of it. The problem is the way that light behaves as described by Dr Einstein in the Special Theory of Relativity. The speed of light in a vacuum is constant, regardless of the motion of the source or the observer. If you are traveling toward a star at .99 x the speed of light, then the light from that star will still pass you - relative to you - at exactly the speed of light. In the same sense, the light from a star behind you in the same scenario will also pass you at exactly the speed of light - relative to you. This seems counter-intuitive and strange, but it has been demonstrated in laboratories and astronomical observatories countless times over the past century and a half or so. This results in the effects of time dilation and length contraction at near-light speeds that you may have heard being discussed (e.g. the Twin Paradox, where a space traveler ages slower than his stay-at-home brother). These are not illusions nor tricks, they are in fact very real effects. So if the light from a distant source always passes you at the speed of light, then it is impossible to reach a speed where it does not pass you at that speed - in other words, you cannot travel along with the photon. It will always pass you at the same speed, no matter how fast you try to go.  In fact, it would theoretically take an infinite amount of energy to achieve that, and there is no way to obtain an infinite amount of energy. The laws of physics as currently understood prevent travel at faster-than-light speeds. That's the way our universe works.

Answer 3

because as you accelerate close to the speed of light, the amount of energy required to continue accelerating a given mass increases.

Answer 4

Well if you go faster than the speed  of light there is too many g forces. Look up Einsteins theories about it.

Answer 5

Gravity is a property of the space-time continuum, and it is ubiquitous in the universe.  The effects of gravity are not felt in the same way off the surface of a planet, but actually all objects in space are equally affected by gravity.

The speed that an object can be moved through space is limited by the amounts of energy required to accelerate objects to high speeds, and by the relativistic effects associated with the speed of light.

The amount of energy necessary to accelerate an object to a relativistic speed (say 1/10 the speed of light) is more than the energy produced by 200-300 stars.

So we sit on the porch and practice the banjo.  At least that will get you somewhere.