OT: Things that go bump in the night
LeatherGryphon
Posts: 12,081
Gravity waves detected! Can warp drive be far behind? 
Post edited by LeatherGryphon on
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Detecting them is a LONG way from generating them......
Of course, but knowing that there IS a needle in the haystack is helpful.
The detection of all we've learned about the universe so far has been dependent on the electro-magnetic spectrum.
Gravity waves are outside of that.
The future benefits of this discovery we can't even imagine.
Gravity isn't affected by small particles like cosmic dust that distorts what we see on the visible spectrum, if we can see gravity we will get a very clear view of mass and the interior structure of things very far away.
Is that the one NASA tested to debunk, and found that it really did produce a tiny bit of force they couldn't account for? (IIRC, the force in question was about 1/3 the weight of a housefly.)
The theory is that, somehow, the EM drive is accelerating virtual particles. Which means a ship with EM drive would be able to accelerate without carrying reaction mass.
Or it's a design flaw or a bunch of instrumentation errors that are confusing the issue, since the force involved is absolutely miniscule.
But a drive like that would free us, somewhat, from a prison of space.
I'm always a bit sceptical about low acceleration drives being a practical way to commute. Sure we can get going really really fast but very slowly. We'll get to our destination but zip right by it unless we turn around at the half-way point and start decelerating really really slowly. I guess we could use air-braking like at mars to use the atmosphere to slow us down but not a viable option for visiting asteroids for mining or airless moons for colonization.
Low acceleration drives would be good for zipping out to pluto or going to the nearest stars in a practical amount of time but we'd have to have a really fast camera!
<Insert some irradiant conspiracy theory here>
...<,not nbefore I find my roll of tinfoil>
LeatherGryphon: At least some folks think that if the drive does what they think it does, it should be possible to have a much higher acceleration rate.
But at that point you're piling supposition on supposition.
At the VERY least, it'd be amazing for effective probes and other stuff.
Also, again, not having to carry reaction mass is a HUGE deal. Economies of scale kick in fast, and you'd be able to make ships much more cheaply and long trips would still be faster, in many cases, than conventional technology.
There's a lot about possibilities here: http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/
From the article:
Mr. Joosten and Dr. White stated that “a one-way, non-decelerating trip to Alpha Centauri under a constant one milli-g acceleration” from an EM drive would result in an arrival speed of 9.4 percent the speed of light and result in a total transit time from Earth to Alpha Centauri of just 92 years.
However, if the intentions of such a mission were to perform in-situ observations and experiments in the Alpha Centauri system, then deceleration would be needed.
This added component would result in a 130-year transit time from Earth to Alpha Centauri – which is still a significant improvement over the multi-thousand year timetable such a mission would take using current chemical propulsion technology.
Yes, a 130 year mission is pretty f'in ambitious, but there are buildings people have been working on that long. It's at least within the scope of possibility (and that's at a paltry .001 g thrust), rather than the scifi 'maybe immortals would go on 20k year missions.'
To be fair, there are some, um, big criticisms of the drive:
http://rationalwiki.org/wiki/EmDrive
...70 days transit time instead of nearly a year, almost makes a manned Mars mission sound reasonable.. Still some big hurdles to surmount considering the ISS gets routine supply ships to replenish its supplies and life support while a craft on the way to and from Mars will be pretty much on its own.
"Last Chance Gas" is in HEO and it's a long walk back.
While I am curious about VLA (very low acceleration) EM drive experiments I don't see them as more than curiosities until proven and then explained properly to be able to take full advantage of them.
However, back to the original topic, the declaration of detection of gravitiy waves is a big deal. This is something predicted but unproved for a hundred years. It's at least as big a deal as the detection of light bending around the Sun and the explanation of the errors in Mercury's orbit and measurement of time differences based on altitude above the Earth. These are pilars of the whole theory of General Relativity. Knowing we're on the right track is encouraging.
Sure, warping of space for Star Trek-like interstellar travel faces a lot of issues but now they're engineering issues, not theory issues. (Anybody know where to get a really big can of "negative energy" or a tiny black hole?)
I'm holding out for dilithium crystals.
I'm waiting for the Vulcans.
What I hope to learn from this is the makeup of empty space. Gravity waves propagate through space/time, electro-magnetic radiation propagates through space. The wave/particle duality requires a particle (photon) to move through empty space because the wave action itself requires particles to act upon in order to propagate, the assumption being that empty space is a vacuum without the 'necessary' particles.
We know from quantum mechanics that particles can spontaneously appear out of the 'nothing' of a vacuum. (Are these the 'virtual' particles that drive the EM acceleration?). Do these particles actually exist undetectable in the vacuum?
Gravity waves have gravitons as their particle but there is also an actual wave that drags time along, as space twists and turns, time accelerates and decelerates. This is an entirely new ballgame. Physicists have probably thought this out so that everything I've said is old hat and nonsense to them now. Having actually confirmed the existence of gravity waves then perhaps they'll begin to let us in on their current thinking.
I attended Florida Institute of Technology at the time (1966) a new college with many of its teachers & professors still having full or part-time jobs at the Kennedy Space Center. FIT was the first college in the country to have an actual curriculum and degree program called "Space Technology". Like most colleges, the attrition rate among all degree programs was rather high the first year. But the campus joke seized on the idea that first year students were there just taking up space.
But seriously, I can almost wrap my brain about particle/wave duality for electromagnetics & Strong and Weak forces but applying the same concept to gravity makes my brain hurt. As you say, they work WITHIN spacetime. But Gravity works ON spacetime itself. We know there are problems merging General Relativity to Quantum Mechanics so there are some assumptions that might be wrong. Could assuming there is a gravity "particle" be one of them? Don't know. Haven't got the math to argue. I just feel like we're missing something here. But this discovery of gravity waves IS significant if only to pin down a little bit more of the theory and give us a chance to grapple with the wiggly bits.
Currently wnen letting my brain wander in unusual directions I keep finding myself asking "WHY does light have a speed?" Sometimes I think I've found a trustworthy explanation or reasoned it out myself, and ever so briefly I have an epiphany and it becomes obvious but the moment quickly passes. I know there is an exciting and illuminating answer but it's like trying to understand television while blind.
Love it. I've often thought about when physicists 'see' a particle change spin, it's 'sister' across the room, so to speak, changes too. Einstein's 'spooky action at a distance'. I think they're actually looking at the same particle in a different way. Then I go off and do the dishes and don't think about it again for months.
<don tinfoil hat>
About the "spooky action at a distance" (i.e. "entanglement") I think I've worked that one out, at least for photons. A photon in itself has no future or past. Experiences no time. It is free of the cling of the Higgs field. From the photon's point of view it leaves its source and arrives at its destintion simultaneously whether the distance is the atom next door or at the other side of the Universe. So, whatever state it or it's entangled partner is in, is of course, instantaneously manifested. For them it's only always "now". It's just for us poor blobs of matter mired in spacetime, truding through the Higgs field, to ponder "how in hell did that happen"!
<doff tinfoil hat>
Ah, ... I reread your idea. Hmm, looking at the same particle from a different point of view...
<don tinfoil hat again folks>
OK, yes, possibly from our point of view. Considering it's not a particle but a wave, it's all part of the same construct seen from our point of view as through wonky prisms of spacetime limitations. Artifacts of multidimensional distortions?
<doff tinfoil hat>
Ow, brain hurts.
I just find it mindblowing how far ahead of everyone else Albert Einstein was.
I had an interesting read over the holidays. Go read Arthur C. Clarke's "Rendevous with Rama" sometime. The ship discovered in that story has a "star drive" with no reaction mass propellant. He doesn't explain that, but he does explain how you deal with taking thousands of years to cross the interstellar gulf. You don't put people to sleep, you don't freeze them. You build an enormous ship with a frozen "ocean" of a primordial soup containing all the building blocks of life. When the ship gets where it's going, all the machinery on board wakes up and reconstructs all the life of the planet of origin from genetic blueprints. The ship had no living inhabitants, only machines. Machines to fix the machines, machines to recycle machines that broke, all this machinery just to reconstruct the race that built the machines. An elegant solution, once you have a drive with no need for reaction mass.
I'm fond of saying that true spaceflight won't be possible until chemical rockets are considered as obsolete as buggy whips...
Those spontaneous particles are virtual particles, yes. Whether the EM drive actually does that is still, er, unknown. But maybe!
...so is there a Cochrane family somewhere?
...I always wondered if there was such a thing as "slow light".
Google is your friend: http://www.gla.ac.uk/news/headline_388852_en.html
But don't think that this means that the slowpoke photons are not travelling at the speed of light! It all comes back to my question of "WHY does light have a speed?"
I read somewhere recently (a couple of times) about an experiment that measured a pressure forcing two parallel plates toward each other because the space between them was quantumly restricted from permitting as many virtual particles to "pop" in and out of existence, as in the space outside of the plates. Demonstrating that virtual particles can have measurable effects on physical objects. I looked for the article but can't find it. I thought it was in a recent Scientific American magazine but if so it must have been in one of the smaller articles.
That's the Casimir Effect, I believe: https://en.wikipedia.org/wiki/Casimir_effect