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Fuel Free Spacecrafts Using Graphene
William Robinson writes: While using a laser to cut a sponge made of crumpled sheets of Graphene oxide, researchers accidentally discovered that it can turn light into motion. As the laser cut into the material, it mysteriously propelled forward. Baffled, researchers investigated further. The Graphene material was put in a vacuum and again shot with a laser. Incredibly, the laser still pushed the sponge forward, and by as much as 40 centimeters. Researchers even got the Graphene to move by focusing ordinary sunlight on it with a lens. Though scientists are not sure why this happens, they are excited with new possibilities such as light propelled spacecraft that does not need fuel.
So they'd need to carry hydrogen and split off its electrons or something to neutralize the charge.
(T>t && O(n)--) == sqrt(666)
Where the heck those extra electrons came from? Absorbing photon momentum (more efficient solar sail) sounds feasible, but "accumulating electrons" from nowhere and then emitting them in one direction (where light came from) ... less so.
Paul B.
So it's not really fuel free, the fuel just happens to be on the ground (or wherever you put the laser).
All great discoveries can be summed up with three simple letters... WTF
Lets test your hypothesis by creating a slashdot poll.
Mod me down, my New Earth Global Warmingist friends!
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'hmm... that's funny...'" - Isaac Asimov
Some days it's just not worth chewing through the restraints.
Having read the article, they've already ruled material vaporization out.
Clearly it collects the electrons from the hydrogen particles in the interstellar gas. Of course, the now-charged hydrogen gas follows it around until it gains critical mass and... FOOM! New sun!
Well, CRT face is (weakly) grounded, so e- kinetic energy can excite atom for subsequent photon emission, but its charge will happily leak into the ground.
There is no "ground" anywhere next to flying spacecraft!
Actually, on reading the preprint, yes, electrons come from under the Fermi level, get lost in the process and graphene foam (or, spacecraft carrying it) *will* become charged -- it was pointed out in the article as well, but I did miss it on quick read.
AC below actually paints a rather dramatic picture of what can happen next! :)
Paul B.
Hmmm ... you mean "really cool" in the "it will do more useful stuff" sense of the word? Or in the sense of adding a spoiler and neon running lights to a beat up Honda Civic "might be really cool"?
Or maybe the painted side could have a jolly roger on it to play space pirate?
Honestly, is painting one side functional?
Lost at C:>. Found at C.
A quick search on converting photons to electrons turned this up:
http://cleantechnica.com/2013/...
A new discovery by researchers at the ICFO has revealed that graphene is even more efficient at converting light into electricity than previously known. Graphene is capable of converting a single photon of light into multiple electrons able to drive electric current.
So that could be where the extra electrons are coming from.
Better known as 318230.
So they'd need to carry hydrogen and split off its electrons or something to neutralize the charge.
Actually this could provide more thrust. Use sunlight to propel the craft until it has built up a large enough electric charge that the efficiency of the thrust begins to drop (since it will take an increasing amount of energy to expel the electrons from something with a large positive charge) and then introduce a stream of neutral gas into the sponge. This should strip the electrons off the gas and the remaining positively charge ions will then be repelled by the positive graphite and provide even more thrust.
Of course this means that you need to have a fuel source but it's likely to be far more efficient than current rocket fuel plus there it no need for it to be something explosive like hydrogen - you could probably use Xenon which is a noble gas and so extremely inert and so a lot safer.
Combine it with an EM drive: double the speed & double the mystery. Maybe if you mix baffling with confounding you get a multiplier effect instead of just doubling. (That's the way the entropy seems to work with compounded software bugs.)
Table-ized A.I.
That may be correct but the article you linked has an incredibly misleading title. This process does not convert photons into electrons it simply imparts the photon's energy to one or more electrons which, in the case of thrust, causes them to be ejected from the graphite. The coupling of electrons to photons is extremely well understood, in fact it is the second most accurately tested scientific theory ever discovered (the first being special relativity). The only way to create electrons from photons is to also create an equal number of positrons. However this requires far higher energy processes ~1 MeV of energy which is many orders of magnitude higher than the energies involved in visible light and would easily break apart graphite which is something they ruled out.
Actually, just what I was thinking (today nobody remembers Crookes (I named a cat after him)). Key bit of missing information in the article - how good a vacuum? Really matters. And just measuring a hard vacuum as made fools out of a lot of people.
There are other possibilities - our country paid people to publish false and misleading papers (no - they have not been retracted) . This doesn't even become news IMO until it is published and replicated.
The amount of technology that has been 'borrowed' by the Chinese is mind boggling - unprecedented. Yet it takes a particular kind of culture to understand the technology in a way that lets them synthesize further progress. A lot of the papers I see coming out of China are just 'cargo cult science' - looks like science - but it isn't. It takes a particular set of values - held dear and close to the heart - to do real science.
The grant proposal industry has diluted the quality of papers so that a very small minority represent real science. I would think of this as likely just bad science once again.
It is a related principle, photons have momentum and it can be transferred to atoms to increase their kinetic energy, but it is only when it happens coherently that you notice anything more interesting than heat.
Furthermore, their ability to second-guess the credentialed experts is improved exponentially by posting AC.
Do you ever get the paranoid feeling that someone is occasionally modifying the laws of physics in order to advance the plot?
"Oh look, they're going to be stuck on Earth for an excruciatingly long time due to the exponential-propellent-scaling problem. Let's add a new capability to graphene that will give them a work-around for that."
I claim that two years ago the exact same graphene experiment would have shown no unexpected results; but now in 2015 we see this suspiciously useful behavior appear. I'm not sure how to test my hypothesis though :)
I don't care if it's 90,000 hectares. That lake was not my doing.
I wonder if they've weighed the sponges. One possibility is that the sponges are deteriorating in a particular direction, thus engaging in conventional "stuff out one end makes you go the other way" propulsion. And also becoming traditional "will get used up" style fuel in the process. :)
Though it'd be all kinds of awesome if it was creating coherent motion out of energy delivered by photons without wearing out. Now *that* could be a space drive.
I've fallen off your lawn, and I can't get up.
The EM drive is pseudoscientific rubbish. Conservation of momentum is a buzzkill and there's no way around it. As for this discovery, one of two things will happen:
1. They will 'discover' that it uses no reaction mass, in which case it can safely be discredited as pseudoscience.
2. They will discover that there is indeed reaction mass involved. Actually that's what it says there in the article: "Instead, they think the graphene absorbs laser energy and builds up a charge of electrons. Eventually it can't hold any more, and extra electrons are released" If this is confirmed it means that you can't run this for very long because you build up a positive charge and you need to balance this by gaining electrons from somewhere (interstellar gas maybe?) or ejecting positive ions.
If electron ejection is happening then it's really nothing new; we've known that electron guns can propel objects in space. This might lead to new, more efficient ways of using that effect, though. Still, I doubt that the thrust is going to be anywhere near useful for, say, a manned spacecraft. It might be extremely useful for satellites and probes.
A fool and his hard drive are soon parted.
Well, there might be some sort of principle for a new and better ion drive of some sort buried in there. Its all certainly worth investigating, as any "WTF!" moment of this sort is. The hype about reactionless drives certainly is drivel though, and it seems your average peruser of online science fora has little or no clue about small things like Noether's Principle, which pretty well guarantees nobody is violating Conservation of Momentum, ever.
"Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
You don't really have to have much knowledge about anything to second guess experts in any field. Just hold to the rule that "all amazing results are caused by inaccurate measurement, poor sampling, cognitive leaps or coincidence" and you'll be right 70% of the time.
The actual breakthroughs will be so old hat by the time they have been tested properly that nobody will talk about them and you'll never eat crow.
Remember, cynicism and wisdom lead to the same result most of the time, only wisdom is so much harder to learn.
When Argumentum ad Hominem falls short, try Argumentum ad Matrem
Article says they tested for that, and the tests show that the material is not losing atoms. It seems (according to further tests) that the graphene sponge is absorbing energy from the directed light (they repeated the experiment with sunlight and a traditional lens, with similar results) and finally reaches some sort of critical mass, and sheds electrons in a stream, rather than in random directions, resulting in thrust. If this whole hypothesis pans out, the difficulty in making a space craft that makes use of this phenomenon is that it would eventually build up a large positive charge, which would eventually damage the craft, if it can't be dealt with.
I've decided to Diversify my Holdings. I've divided my cash between my left and right pockets, instead of all in one.
Welp, I've got a laser pointer and a table, you find us some graphene sponge and a vacuum chamber, and we'll test it. Which is the whole point of this. Its literally:
"Hey scientists of the world, we pointed a laser at some graphene, and something weird happened. Here's what we did, will you give it a go and see if we're tripping balls, or have discovered something awesome?"
I've decided to Diversify my Holdings. I've divided my cash between my left and right pockets, instead of all in one.
However, electrons are very nearly massless, so unless they're somehow exciting them with massive amounts of energy, the propulsion from the electrons is unlikely to be significant.
It depends on what you compare it to. Since this process was hitting the graphite with photons it makes sense to compare the thrust produced to that created purely by bouncing photons off a material. Electrons might be light but they have more mass than a photon and so the thrust should be significantly higher.
I'm no physicist, but I'm pretty darn sure a spaceship's gotta move a whole lot further tan 40 cm to get anywhere.
File under 'M' for 'Manic ranting'
http://en.wikipedia.org/wiki/G...
I would call that attacked for his scientific work. He was placed on house arrest (for life) in 1632.
"So long and thanks for all the fish."
He definitely was attacked for his scientific work - heliocentrism was banned and Galileo had been investigated multiple times. However he did himself no favours by putting the pope's words into the mouth of a character called Simplicio who is depicted as a fool.
No, it's not pseudoscience.
If a researcher perfoms an experiment and gets a very strange, unexpected result, what should he do? Say "that result is clearly impossible, so I shall just disregard it"?
No, he will try to repeat the experiment, gather data, and try to figure out what's going on. Maybe (most likely) there's a perfectly valid explanation within existing scientific frameworks, maybe it's a setup or measurement error, or maybe, just maybe, this is a new effect that hadn't been discovered yet. So the scientist tries to figure that out, and tells others about the experiments so they can try the same thing and see if they get similar results.
That's how science works.
I'm sure you would have called the theory of relativity "pseudoscience" back in the day of Newtonian physics. New things do get discovered sometimes. As long as it's being researched using scientific methods, that's science and not pseudoscience. Yes, they probably will be wrong. That doesn't mean it's not science.
If I read this correctly, the decisive advantage this has over conventional solar sails, is that instead of turning a fraction of the (feeble) momentum of photons into useful movement (basically by bouncing photons around), this discovery turns (apparently, most of) the energy of those photons into a coherent emission of electrons, which give off orders of magnitude more useful momentum.
So, it's not quite a solar sail, but rather a very very very light and efficient solar-powered electron cannon.
Maybe we deserve this world ?
Set up a Slashdot server on board the space ship. You'll have an unlimited supply of negativity, so much so I think if you dumped a cup of tea on it the ship will instantly jump to ludicrous speed.
If conservation of momentum were not true, it would break 99.999% of our understanding of physics.
FTFY.
If man's law defining conservation of momentum is found to have a loophole, then physics as defined by the universe will work the same way it always has. It's just our definition that's been broken, which would mean that every other theory we've created that's been supported by this law would have to be brought back to hypothesis and reworked into a new theory of how things work based on new evidence.
To think that it's unlikely that conservation of momentum will be discovered to have a loophole we didn't understand doesn't make you the 'religious shitreaded fanatic' [sic]. I also highly doubt that we'll find that loophole, even with this new discovery, and I feel that all the laws of physics have been fairly solidly proven thus far that they can be safely presumed to be a certainty. That said, I would not be so arrogant to say that if it were discovered that one of our laws was flawed that physics has been broken. I would only say that man's understanding of physics has been shown to be flawed and that we must come to understand that flaw so that we can rework a more complete understanding of the physics of our universe that correspond with this new information.
Anytime Galileo is brought up it's as proof that the Church is/was anti-science; which is patently false. Don't get pissy because your example is bad.
I doubt that.
When someone says, "Any fool can see
If momentum is not conserved. Neither is energy nor relativity. So all those experiments must be in error somehow... or your wrong. Forces are *between* things, so momentum is conserved. So is energy and its all relative.
A good scientist doesn't waste time on bullshit. And violating momentum conservation is bullshit.
If information wants to be free, why does my internet connection cost so much?
From the New Scientist article, they talked about the possibility that the incoming photons boil off electrons from the sponge, and most of those electrons were emitted in the opposite direction of the light beam, generating more thrusts than can be accounted by just the light pressure alone.
They also raised the issue that, if that were actually the case, you would end up with a dangerous level of positive charge. Without being able to neutralize the charge, this would not make for a good propulsion system.