but if somthing is 100 lightyears away & you travel at a million lightyears then how come people at point B would age by 200 years?
hes travelling at 186000000000 miles a second.
If I drive to London & back, i still age exactly the same amount as someone left back home?
I dont quite get what youre asking.
If you drive to london and back, youre not going at the speed of light. Did you ever do the difference of the speed of sound and light in physics, where you class went into a field and someone made a noise by kicking a ball or something at the other end? How you saw it happen before you heard it?
Its sort of similar here. Except something takes 100 years to travel to. Its not possible to go faster than the speed of light. So say you left as your star blew up, when you arrive at your destination, if you were at "lightspeed" you would see your star blowing up, but if it was 100 light years away, in reality the location of the star, or its remains, would be 100 years in the future.
The issue encountered in the novel is that the device for getting them from A-B is known to defy some laws of physics, it ALWAYS takes a fraction of a second for the ship to go from A-B, no matter the distance, but as it cannot go faster than light everything ages around them. On their last mission the squad goes so far that I think it took them 750 years to get there and back, but to them it was only a year (as they had to speed up and slow down without becoming pancakes)
I Dont buy the argument you cant go faster than the speed of light... I dont believe going faster = time travel bollocks either.
Quite simply nothing goes faster than light, but its not that simple so keep lets it as simple as possible and use rocket motors at a lower speed insead. Rockets use fuel, which is burned and goes out the back. Part of the energy supplied by goes into propelling the ejected fuel backwards and part into heating the exaust gasses and part into pushing the rocket forwards. Eventually the shp will run out of fuel, and you are accellerating the fuel on board as well as the ship, which isnt a good idea. So lets give it infinite fuel from a cornucopia. You would think that the rocket would accellerate forever, and it does, except the fact that the exhaust gasses have a limited speed, the closer the ship gets to this speed the less benefit it gets from burning fuel. Eventually the accelleration is so little as to be inconsequential and, if you were to keep burning fuel nearly forever, the ships speed would stabilise at a tiny fraction below the limit. The end result is that it can never exceed the maximum speed of the gasses going out of its exhaust.
OK, so switch the fuel for light, and the cormucopia is pushing it out the back directly, so you are getting the full benefit of lightspeed accelleration (whatever that is, lets just assume it works for the moment). You accellerate towards light but the result is you can never actually pass that speed. Its similar to a car running out of oomph at its top speed while you are driving across an infinite flat plain.
As Light is the fastest thing going we know of in a vaccum that is the speed limit. There are however certain ways of getting light to go faster or slower than itself in special mediums and under certain conditions. Light in atmosphere, water or through strong gravity travels slower than in an average space vaccum.
As to the person travelling at the speed of light, speed affects local conditions, especially time.
When we speak of time what we refer to is the speed of change, how fast something alters. A chemical changing state, the water or sand from one container pouring down into another, the tick of a clock or our bodily processes such as hartbeat, the speed of light are part of this. They only happen on a local basis and relative to the conditions of where they are. Trying to say that two distinctly different systems have to experience the same time isnt an option, even if they are only inches apart.
A person who is travelling faster experiences less time passing than a person travelling at a slower speed. Even at relatively low velocities this is measurable, the time clocks on Satnav satelites have to be corrected daily or you would end up driving to the wrong place. The person driving to London and back would also experience some time dilation, but its so small as to be inconsequential. So the person who drives to London and back has experienced more time than the one that has spent the time space travelling at light speed.
This folds back on your maximum speed too, as the ship gets closer to the speed of light it slows local time, so the cornucopia produces substantially less light than it did at a lower speed, which again reduces accelleration.
The effects of this are well documented, as are the expected effects of travelling close to the speed of light. As you approach it things outside speed up in relation to you. For a stationary person outside your ship you would slow down, but thats relativity. The next effect is that light from suns would gradually congregate together at the front and back of the ship into single points. Finally, if you do reach lightspeed, time stops for you, so you experience nothing. This is not a good idea as you cant control your ships direction or velocity, until you hit something you are totally helpless, although if you do hit something the chances are you are going to die instantly. Automatic systems on board your ship are governed by the ships internal time too, so they dont work. You might outlive everyone in the universe by doing this but I doubt it will make any difference as you wont experience anything.
BTW this isnt time travel but time dilation, slowing time down is a known fact. I will leave time travel to Steve F or someone else.
