At 12:00 PM 11/4/2009, Horace Heffner wrote:
As a passenger in a 1 g ship, it would appear you can effectively go faster than c because the distances appear to shrink.
If they appear to shrink, then why would you think that you are going faster than c? What you'd see was this road whizzing by with mile markers that were closer and closer together. Why would you think you were travelling faster than c? Only from a memory of how that universe looked like before it shrank!
So you'd look at the road signs that are separated by an inch, and you'd see, say, one that is mile marker 349786920, and, then a second later, one that says 350086920, and you'd say, wow! we are travelling at 300,000 miles per second! I don't think so!
Yes, if you are sitting "still" and want to travel to some far star, and you can accelerate to however close you want to the speed of light, you can get there is practically no time at all, once you are going fast enough. But.... there is still this little problem of a few hydrogen nuclei in the way. They would be coming in with how much energy and at what rate?
If you could ride on a photon how long would it take you to travel a light year? Zero seconds. From the viewpoint of the folks at home, you never go faster than c.
Nor from your viewpoint, either. Only with a "mixed viewpoint," where you measure distance based on what it was when you were at home, could you say this.
That is because the information about you, your messages, your telescope image, arrive back on earth at c. Further, as you approach c, the quality of the information about you degrades as you depart, it drops in frequency. If instant quantum communication can be sustained through acceleration, then it is a whole new ball game. Relativity is out the window. The folks at home can watch the whole journey from your perspective. More importantly, you don't even have to go. You can just send robots and stay home and watch.
If. No indication at all that it can happen. Actually, instant communication would not reduce the time it takes to get there. I.e., if you can sent bots at high acceleration sufficient to reach near-c, that can communicate back when they get there instantaneously, and it would take enormous energy to do this to the nearest stars, you'd still be limited by the time it takes for the bot to get there. That's in your frame. So as many years, minimum, as it takes light to go to the place. And then you'd have the teeny problems of how to manage a quantum entangled signal back home over that distance. Maybe you could carry a lot of entangled photons home and leave the pairs behind. You've already sent the signal, and have received it, when you were home. "Do Not Open Till Arrival." So how to you send a signal this way? Beats me.
If you can go across the galaxy at what appear to you to be multiples of c, or compress the distance by a comparably large fraction, and actually arrive somewhere, it shouldn't matter what the folks at home think they know about your progress. That doesn't change the fact you arrived.
Yes, you can get there fast, if you can approach the speed of light. And can survive the onslaught of the radiation and mass attack. Somebody do the math if they want do, I don't.
