101–110 of 194 posts
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It's not boring, it's just too big and therefore too slow for our tastes. If we lived 5,000 years, taking a 100 year trip to Alpha Centauri might not seem so bad. I think extending lifespan like this is more likely than building an FTL drive.
My concern is the mismatch between the timescale we communicate with people and the timescale of the trips (minutes or hours vs centuries). It would be such a massive transition during your trip that it is hard to adequately describe it.
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No, it isn't. Light is unique in this way.
Correct. In a bit more detail: Here's the grid coordinate system for the streets in my town. One intersection is (0, 0). But in the grid system used by the next town over, that same intersection is (100, 200). And that's fine - we're just shifting the origin, which changes all the numbers. The same thing happens with velocity. If I'm on the ground, "stationary" means that you're not moving with respect to the ground.…
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That was sort of a primary plot point of the Ender's Game series.
I wouldn't say primary plot of Ender's Game. I'd say it was a higher focus in Speaker for the Dead. Still, the device is used in a lot of Sci-Fis. Card wasn't even the first to use the term Ansible, though he did use that exact word.
Everyone always talks about FTL travel for spacecraft, but there's also an interesting perspective from weapons side (and this a reason to be a bit careful and think about some ethics as we move along). A FTL kinetic weapon would be devastating. If it comes with a collapsing warp bubble then there's basically a gamma ray "gun" that travels right in front of your mass that is traveling at tremendous speeds. You look a…
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General relativity actually tells us nothing about whether causality is absolute. You can easily make up spacetime configurations that violate causality and still conform to general relativity. It's just that most people believe that causality should be protected, because... well it would be really weird if it wasn't. But it's just a conjecture and not like a theorem or anything.
AFAICT, GR is symmetric in relation of the direction of time, as are most other important physical theories. What may add the arrow of time is the second law of thermodynamics: a statistical evolution of a system is not symmetric. I wonder now how a violation of causality could either circumvent of contradict the second law.
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No, the meter is defined in terms of c and the hyperfine transition frequency of Cs-133 is defined https://physics.nist.gov/cgi-bin/cuu/Value?nucs . If that link isn't good enough, you can check out the SI Mises en pratique on the subject: https://www.bipm.org/en/publications/mises-en-pratique Edit: I'm totally this guy right now https://xkcd.com/386/
> the meter is defined in terms of c That is what I just said: the meter is defined in terms of c, not vice versa.
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It's not creating new energy, right? It reads to me like causality violating configurations simply move energy around time as we'd move mass through space.
The second law, like all physical laws, does not violate conservation of energy. However, reversing causality can cause the reversal of entropy, which is what the second law deals with.
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Progress in warp field research though has resulted in significant energy reductions though - everytime a more efficient formulation is found its a step on the way to a possible practical system. After all, if it was easy then everyone would be doing it.
"if it was easy then everyone would be doing it": And, I suppose, we'd see them. Little green men, I mean.
Maybe it is feasible to build an FTL engine, but maybe it can only feasibly go at like 4c. That doesn't make it very easy to drop by our solar system and have a look at what all that radio noise means, even if anybody's heard it.
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We're all traveling through spacetime at the speed of light, most of our velocity is in the time dimension, the faster you translate in the x,y,z dimensions, the less is left over for the time dimension, and thus time seems to slow down. (That's how this non-physicist things about it, anyway) In a warp field, you're just somehow shrinking X,Y,Z while not doing the same to time. I see no reason to think you'd travel b…
Your thinking assumes a preferred reference frame. https://en.m.wikipedia.org/wiki/Relativity_of_simultaneity