Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

thedrive.com

Post reply on HN
Print view View original

91–100 of 161 posts

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

#91

Post by coldtea »

rurban wrote: post #70
duchenne wrote: post #61

I love the following Feynman's quote: ``In those days, one of the theories proposed was that the planets went around because behind them were invisible angels, beating their wings and driving the planets forward. You will see that this theory is now modified! It turns out that in order to keep the planets going around, the invisible angels must fly in a different direction and they have no wings. Otherwise, it is a s…

Gravity is very similar to magnetism, a "magically" attracting force of distinct objects. The explanation is very easy via fields. Just trying to explain it via particles will get you into trouble, e.g. the flawed standard model, or the Higgs. Einstein was pretty close in his spacetime bending explanation, but this still doesn't explain dark matter or the recent gravity experiments with fast rotating magnets in stron…

>Gravity is very similar to magnetism, a "magically" attracting force of distinct objects. The explanation is very easy via fields.

The explanation of how gravity is applied is easy via fields.

Not why gravity attracts and what causes that...

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

#93

Post by Erlich_Bachman »

nnq wrote: post #69
lisper wrote: post #46

Earlier quoted context omitted.

How much money does society need to spend supporting the work you do before we can safely conclude that Einstein was actually correct and we don't need to test it any more?

Hopefully a (theoretically) infinite amount (assuming infinite time) ...theories should continuously be re-tested, although it probably makes sense to spend an exponentially lower and lower amount of money on re-testing theories we know are true. But they should be re-tested, even if some experiments you'd only redo every 50 years or so! For two important reasons: 1. as a species we must maintain technical capability…

Wouldn't we very quickly notice if any of the basic laws of phsyics would change, or if any of the physical constants would nudge even a fraction of a million - because our machines (like microchips, radios, like quantum computers, like satellites, GPS, etc. etc.) would stop working as they were intended?

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

#94

Post by Erlich_Bachman »

duchenne wrote: post #61

I love the following Feynman's quote: ``In those days, one of the theories proposed was that the planets went around because behind them were invisible angels, beating their wings and driving the planets forward. You will see that this theory is now modified! It turns out that in order to keep the planets going around, the invisible angels must fly in a different direction and they have no wings. Otherwise, it is a s…

When you go deeper, it is like that with every part of physics. We don't understand any of it. We just move the horizon of understanding farther and farther, we are not even pretending to know what is behind it. Care to explain where the big bang came from and why did it give birth to these specific sets of physical laws and this specific number of elements and why are there just enough forces and randomness for them ot produce biological life and not kill it instantly with all chaos and random motion etc? Why is life somewhat stable? Science never really "explains" anything, it just learns to describe, model and predict the observations better and better. Observation is all we have.

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

#95

Post by raattgift »

ISL wrote: post #51
lisper wrote: post #46

Earlier quoted context omitted.

How much money does society need to spend supporting the work you do before we can safely conclude that Einstein was actually correct and we don't need to test it any more?

That's a great and important question. (doubly so for me, as constrained resources may see me leave the field, to which I have devoted my entire professional life, in the coming months) We are perennially grateful for the support we receive to do the work that we do. To a high degree of approximation, Einstein's predictions are very, very correct. We are trying to look very carefully at Nature because we don't think…

> constrained resources may see me leave the field

I am sorry to hear that - it will be a loss for Eöt-Wash.

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

#96

Post by chrisacky »

zzzcarrot wrote: post #87
ISL wrote: post #27

Physicists have been searching for variations in the coupling of materials to gravity for more than a century, and by some measure, for more than a millenium. https://en.wikipedia.org/wiki/Equivalence_principle#Tests_of... Every experiment anyone has ever tried has come up empty. The equivalence principle is a postulate (Einstein's "happiest idea") that underlies General Relativity, making it essential to test. (Sour…

So we are litearaly at square 0 still here?

No, sounds like we've eliminated 70 years worth of other possible squares.. if you want to take glass half full approach.

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

#97

Post by Firadeoclus »

majke wrote: post #80
timonoko wrote: post #54

Earlier quoted context omitted.

It is an illusion. You are floating freely in the space, but massive mass near-by is causing curvature in space-time. In other words: Time goes more slowly in your shoes, because they are closer to the mass. This causes any movement to be circular movement, which is pressing you to the near-by mass, which you experience as "gravity".

Wow, what an excellent way of phrasing it. Give me more. Why "any movement is circular"?

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 remaining in a static configuration around the object whose path we are considering.

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

#98

Post by yourapostasy »

chrisacky wrote: post #96
zzzcarrot wrote: post #87

Earlier quoted context omitted.

So we are litearaly at square 0 still here?

No, sounds like we've eliminated 70 years worth of other possible squares.. if you want to take glass half full approach.

Similar to the realization that saying "no" is one of life's important skills to internalize. Closing off possible avenues of explanation is just as much of an advancement as finding evidence to support an explanation.

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

#99

Post by Zenst »

ISL wrote: post #47
jeffdavis wrote: post #44

Earlier quoted context omitted.

Assuming we find dark matter, do you think it will represent some departure from our current understanding of gravity and how it relates to mass? Or do you think it will just be some boring dust clouds?

We have already tested the equivalence principle toward dark matter [1]. It appears to fall like everything else, at the 1% or better level. It is extremely difficult for modifications of gravity to simultaneously fit the cosmic microwave background, big-bang nucleosynthesis, galactic rotation curves, and the Bullet Cluster. The safe bet these days is on some sort of non-baryonic dark particle (which is why so many p…

From my understanding `dark matter` is an explanation for what we expected and what we see regarding the mass of the universe?

It's a bit like exploding an apple and measuring all the bits that fly of and missing some bits. Whilst we do not know what the apple looked like initially, we are from our measurements, trying to reconstruct that apple.

How convinced are we that their is dark matter and not a case of how we have measured things so far. Hence, differences in results based upon how we measure are evident, whilst many are close to the same, they just don't exactly match up - hence - dark matter theory.

How likely is it that dark matter as we know it - does exist?

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

#100

Post by saalweachter »

hackerbabz wrote: post #77
mLuby wrote: post #2

There are Gravity Stones from the 60's scattered among US colleges to > "remind students of the blessings forthcoming when a semi-insulator is discovered in order to harness gravity as a free power and reduce airplane accidents" Decent way to get students thinking about it. https://en.wikipedia.org/wiki/Gravity_Research_Foundation#Mo...

Why did he think to mention airplanes? The whole concept of airplanes would be obsolete with anti-gravity.

I feel like in 40% of SF stories it will at one point be important that your spaceship not have the glide ratio of a buttered brick, even if it has an antigravity drive.
Post reply on HN