Military Has Been Researching "Anti-Gravity" For Nearly 70 Years

Post by throwawaycanada » Thu, Oct 31, 2019, 6:44 PM UTC

Jyaif wrote: post #130

salty_biscuits wrote: post #111

Earlier quoted context omitted.

"GPS is impossible without corrections from both special relativity and general relativity" I appreciate your comments in general, but I feel that this point needs to be tempered. Yes there are corrections due to SR and GR effects in GNSS, but they tend to get lost in the morass of the least squares residuals compared to all the other much bigger effects, like clock errors, orbital errors, ionosphere delays, etc, etc…

Also, we surely would have compensated for relativity experimentally: "The clock seems to run 0.2% more slowly than predicted. We don't know why, but if we subtract 0.2% everything just work. Let's ship it!"

Post by DoctorOetker » Thu, Oct 31, 2019, 6:58 PM UTC

zitterbewegung wrote: post #13

kiba wrote: post #6

Earlier quoted context omitted.

Time travel back into the past is understood to be impossible.

Yes, a more in depth analysis of this can be found at https://en.wikipedia.org/wiki/No-communication_theorem

Post by rbanffy » Thu, Oct 31, 2019, 7:03 PM UTC

TeMPOraL wrote: post #106

Firadeoclus wrote: post #97

Earlier quoted context omitted.

It seems to me that, as soon as there is mass in the universe which curves space-time, all paths of movement are closed. To a first approximation, for anything close to a single large mass that means an elliptical path. That assumes, of course, that an instantaneous "path of movement" is something that is even worth considering, given that it ignores the time dimension and the fact that all those other objects aren't…

I would think that parabolic trajectories only close in infinity, and hyperbolic not even there? Or both close only in infinity? The math on that is currently out of my brain's cache.

Post by codebc » Thu, Oct 31, 2019, 7:32 PM UTC

amdavidson wrote: post #135

fsh wrote: post #49

Earlier quoted context omitted.

It is a common myth that nuclear reactions "turn mass into energy". What actually happens is that the products of the reaction have less binding energy than the initial nucleus. Since energy gravitates, this reduces the mass of the products. The exact same thing happens in chemical reactions. If you burn something, the product are lighter than the initial substances by the mass equivalent of the energy released.

"...energy gravitates, this reduces the mass of the products." "...the product are lighter than the initial substances by the mass equivalent of the energy released." How are these not restating "turn mass into energy"? Both scenarios approximate: High Mass => Low Mass + Energy

Post by vokep » Thu, Oct 31, 2019, 7:46 PM UTC

cartoonworld wrote: post #142

jbattle wrote: post #34

Earlier quoted context omitted.

I've never understood why "paradoxes make cause-and-effect-reasoning difficult" concerns are a valid argument that something could not be possible. Does physics care whether the workings of the universe are accessible to our logic?

If I look at a random numeric oracle of 1-10, and consider the result as N, and apply to it some kind of mathematical formalism of: If ( N + 10 = 20 ) then eat(last_bagel) My wife comes home and is cross with me for eating the last_bagel. So, I hop in my handy time machine, travel back to before the time where I access the oracle, and alter it to only produce a random number from 1-9. If I succeed, my wife is no long…