Time Travel and Faster than Light

#20 by martinc on 01 May, 2016 15:10
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1) you can describe the system in its entirety using a single frame. For example, you can describe the system in the rest frame if you wish, which would be to say that the rest frame calculates the rocket to move 1 light year in 1.4 years. Or you can describe the system in the rocket's frame, which is to say that the rocket moves 0.7 light years in 1 year. But "1 light year in a year" is right out!

Hi 1,
how about this.. lets say we focus on the rocket's frame and the lucky travelers on board
If they are leaving a star system and travelling to another that is 1 light year distant, that is a fixed distance to be traveled as measured in miles
If they then take 1 year to get there, (to simplify assuming instant acceleration and deceleration) as measured by them, a person on-board who didn't understand relativity (let's say the captain!) might say this.. even though it assumes a certain reference frame - what i'm getting as is i'm curious how future people will express things, and how average joe's would see it in those days.

The other thing i was getting at was to try and clarify that one could travel a 1 LY distance in less than a year (ships perspective) without going FTL, due to space compression/time dilation
These same effects would permit travel to anywhere in the galaxy or other galaxies in a reasonable time, all without breaking any law of physics, as these effects increase in magnitude the closer one gets to c.
That's not to say other problems won't be there which i've ignored for now.. but the common misconception that not being able to exceed the speed of light is a barrier or limiter to our ability to ever do this is wrong?
Martin
#21 by 1 on 02 May, 2016 19:42
Quote from: martinc on 01 May, 2016 15:10
how about this.. lets say we focus on the rocket's frame and the lucky travelers on board

This is fine. However...

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If they are leaving a star system and travelling to another that is 1 light year distant, that is a fixed distance to be traveled as measured in miles

with this, you've jumped out of the rockets frame and into a different frame; presumably the star system's frame. The distance between two points cannot be considered fixed; it can only be defined for a given reference frame. Coordinates in spacetime can be considered fixed (at least at our normal subluminal velocities) but coordinates in space alone cannot.

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The other thing i was getting at was to try and clarify that one could travel a 1 LY distance in less than a year (ships perspective) without going FTL, due to space compression/time dilation
These same effects would permit travel to anywhere in the galaxy or other galaxies in a reasonable time, all without breaking any law of physics, as these effects increase in magnitude the closer one gets to c.

Sure, a traveler could go to many places before that traveler got old and died. Everyone agrees on that. But that was never in question. Remember, it was the question of what 'FTL' means that began this conversation. Consider another, easier to see instance. Two photons are traveling directly away from each other. It's valid to say that the distance between the two photons, from my perspective, is increasing by two light years per year. However, it's NOT valid to say that one photon sees the other receding at 2C.

The point is, mixing and matching coordinates from different frames can lead to amusing but ultimately meaningless calculations. The 'one light year in less than a year' calculation is one of these meaningless calculations; and FTL remains a sci-fi term. A hypothetical trip across the galaxy, properly analyzed, reveals no such FTL-ish effects.
#22 by dr_sepheroth on 08 Jun, 2016 21:07
Every time you speed up everyone around you slows down slightly.
So if you are in your car going 30 Mph then every one else is something like 0.0739433 yotta seconds in the past.

That is a made up example, but the concept is real.

A Yottabyte is 10 to the power 24 bytes, so I just took yotta and applied it to seconds.

If this concept is true then 1 chronoton takes 3/4 of a yottasecond to move from A to B
#23 by martinc on 22 Jul, 2016 10:40
OK, i just re-read the original post and you're right it was talking about time travel
Where the confusion comes in for me, is that I used to believe that if an object was 10 light years away it would take 10 years to reach it at light speed. I think that many people believe this.. hence to them FTL means being able to reach objects by going FTL and not about time travel
When I found out that this was completely wrong that was awesome
A quick google reveals many people do in fact think the way I did and hold this meaning to FTL
I don't know what's to be done about this!
In other words most people know that light and by extension atoms can't exceed c, and they may know about spacetime distorting around objects (ie gravity), but they don't know about spacetime effects at c
To me this is quite profound, or maybe I'm the only one who worries about this...
#24 by catdlr on 08 Aug, 2016 20:04
NASA's Fastest Experimental Light Speed Propulsion Technology

DOCUMENTARY TUBE

Published on Aug 8, 2016
This NASA space video is structured around the experimental project to design a revolutionary speed of light propulsion engine for future spacecraft to travel Interstellar distances. Faster Than Light (FTL) and speed of light travel are nothing new to science fiction, but interstellar travel is the term used for hypothetical piloted or unpiloted travel between stars or planetary systems. Interstellar travel will be much more difficult than interplanetary spaceflight; the distances between the planets in the Solar System are less than 30 astronomical units (AU)—whereas the distances between stars are typically hundreds of thousands of AU, and usually expressed in light-years. Because of the vastness of those distances, interstellar travel would require a high percentage of the speed of light, or huge travel time, lasting from decades to millennia or longer.

The speeds required for interstellar travel in a human lifetime far exceed what current methods of spacecraft propulsion can provide. Even with a hypothetically perfectly efficient propulsion system, the kinetic energy corresponding to those speeds is enormous by today's standards of energy production. Moreover, collisions by the spacecraft with cosmic dust and gas can produce very dangerous effects both to passengers and the spacecraft itself.

A number of strategies have been proposed to deal with these problems, ranging from giant arks that would carry entire societies and ecosystems, to microscopic space probes. Many different spacecraft propulsion systems have been proposed to give spacecraft the required speeds, including nuclear propulsion, beam-powered propulsion, and methods based on speculative physics.

For both piloted and unpiloted interstellar travel, considerable technological and economic challenges need to be met. Even the most optimistic views about interstellar travel see it as only being feasible decades from now—the more common view is that it is a century or more away. However, in spite of the challenges, if interstellar travel should ever be realized, then a wide range of scientific benefits can be expected.

Most interstellar travel concepts require a developed space logistics system capable of moving millions of metric tons to a construction / operating location, and most would require gigawatt scale power for construction or power (such as Star Wisp or Light Sail type concepts). Such a system could grow organically if space-based solar power became a significant component of Earth's energy mix. Consumer demand for a multi-terrawatt system would automatically create the necessary multi-million metric ton/year logistical system.

https://www.youtube.com/watch?v=W8SUrR8Rb7o?t=001
#25 by ankit240 on 05 Sep, 2016 06:55
Quote from: 1 on 20 Jan, 2016 18:40
Quote from: JarredB on 20 Jan, 2016 15:09
I have read recently that Dr. White and his team at the Eagle works laboratory have had particles accelerate Faster than light.

They haven't. Believe me, you'd know if they had. Velocities greater than c are not well defined in the current framework of relativity. Regarding warp drives, please see existing threads such as:

http://forum.nasaspaceflight.com/index.php?topic=29924.0
and
http://forum.nasaspaceflight.com/index.php?topic=35287.0

Time travel really isn't relevant to this forum.

Only the space between two objects can imerge faster than the speed of light which only occurs at the time of big bang even how hard we try only can reach at 99.99% of speed of light not 100% which is impossible to achieve, but warp drive is another way to travel faster more than speed of light but still it is under research.