So a friend linked me this article http://www.cbc.ca/news/technology/fluid-negative-mass-1.4073937 which talks about a negative mass fluid. I seem to recall that the Alcubierre Drive requires negative mass to function (in addition to rather large amounts of energy) but are they talking about the same thing? I know sometimes terms can mean different things depending on who you are talking to.
If certain quantum inequalities conjectured by Ford and Roman hold,[19] the energy requirements for some warp drives may be unfeasibly large as well as negative. For example, the energy equivalent of −1064 kg might be required[20] to transport a small spaceship across the Milky Way—an amount orders of magnitude greater than the estimated mass of the observable universe. Counterarguments to these apparent problems have also been offered.[1]
Chris Van den Broeck of the Katholieke Universiteit Leuven in Belgium, in 1999, tried to address the potential issues.[21] By contracting the 3+1-dimensional surface area of the bubble being transported by the drive, while at the same time expanding the three-dimensional volume contained inside, Van den Broeck was able to reduce the total energy needed to transport small atoms to less than three solar masses. Later, by slightly modifying the Van den Broeck metric, Serguei Krasnikov reduced the necessary total amount of negative mass to a few milligrams.[1][16] Van den Broeck detailed this by saying that the total energy can be reduced dramatically by keeping the surface area of the warp bubble itself microscopically small, while at the same time expanding the spatial volume inside the bubble. However, Van den Broeck concludes that the energy densities required are still unachievable, as are the small size (a few orders of magnitude above the Planck scale) of the spacetime structures needed.[12]
In 2012, physicist Harold White and collaborators announced that modifying the geometry of exotic matter could reduce the mass–energy requirements for a macroscopic space ship from the equivalent of the planet Jupiter to that of the Voyager 1 spacecraft (~700 kg)[7] or less,[22] and stated their intent to perform small-scale experiments in constructing warp fields.[7] White proposed changing the shape of the warp bubble from a sphere to a torus.[23] Furthermore, if the intensity of the space warp can be oscillated over time, the energy required is reduced even more.[7] According to White, a modified Michelson–Morley interferometer could test the idea: one of the legs of the interferometer would appear to have a slightly different length when the test devices were energised.[22]
So from a layperson's perspective, they both seem to be describing the same thing, although relying on science reporting to get the details/terminology accurate is not necessarily the best bet.
So a friend linked me this article http://www.cbc.ca/news/technology/fluid-negative-mass-1.4073937 which talks about a negative mass fluid. I seem to recall that the Alcubierre Drive requires negative mass to function (in addition to rather large amounts of energy) but are they talking about the same thing? I know sometimes terms can mean different things depending on who you are talking to.
I remember a different article where one of the co-authors explicitly says they didn't make something with negative mass, but that they made something that behaved as if it did have negative mass. I can't find that article now though, so I might be getting this mixed up with something else, but going to the actual paper and the abstract starts out with this
In solid state physics, a particle's effective mass (often denoted m*) is the mass that it seems to have when responding to forces, or the mass that it seems to have when en masse with other identical particles in a thermal distribution.
So yeah, I'm thinking they didn't find or make something with actual negative mass, just a way to get close and fake it to better study it's physics.
Yeah, I don't see how shooting something with a laser can make its actual mass go negative. Sure, lasers are cool, but not that cool. They're saying it has negative mass because when you push on it it accelerates towards the force so it has negative mass for Newton's laws, but gravity seems to still work normally
One of the weirdness of physics things I don't entirely have my head around is the idea that tracking down the source of mass was so difficult. I believe, there is now confirmation that the Higg's Bosson is responsible for mass, but when looking at matter at the sub-atomic level things get weird. Therefore, from a largely ignorant layperson perspective I really don't have enough knowledge to determine if causing a group of atoms to act as a superfluid that behaves according to quantum mechanics, and then changing the spin of the atoms in the superfluid might cause other weirdness at the sub-atomic/quantum scale.
One clue though is in the abstract where it is referred to as a "negative effective mass" which gives a hint as to what the negative mass might be.
A negative effective mass can be realized in quantum systems by engineering the dispersion relation. A powerful method is provided by spin-orbit coupling, which is currently at the center of intense research efforts. Here we measure an expanding spin-orbit coupled Bose-Einstein condensate whose dispersion features a region of negative effective mass. We observe a range of dynamical phenomena, including the breaking of parity and of Galilean covariance, dynamical instabilities, and self-trapping. The experimental findings are reproduced by a single-band Gross-Pitaevskii simulation, demonstrating that the emerging features—shock waves, soliton trains, self-trapping, etc.—originate from a modified dispersion. Our work also sheds new light on related phenomena in optical lattices, where the underlying periodic structure often complicates their interpretation.
P.S. I love science reporting that links back to the original scientific paper.
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surrealitychecklonely, but not unloveddreaming of faulty keys and latchesRegistered Userregular
fronds i cannot emphasise how important this drug is
i mean sure it reverses drug resistance in tb in mice but its called SMART-420
Try the second demo. These will probably be the voices that AGI uses when it announces, in unison, that we are to be exterminated. "Many names, many voices... Hello Humanity - Would you like to play a game?" :bigfrown:
Try the second demo. These will probably be the voices that AGI uses when it announces, in unison, that we are to be exterminated. "Many names, many voices... Hello Humanity - Would you like to play a game?" :bigfrown:
This is great. I so rarely get to feel this unique combo of wonder and existential dread.
Try the second demo. These will probably be the voices that AGI uses when it announces, in unison, that we are to be exterminated. "Many names, many voices... Hello Humanity - Would you like to play a game?" :bigfrown:
Try the second demo. These will probably be the voices that AGI uses when it announces, in unison, that we are to be exterminated. "Many names, many voices... Hello Humanity - Would you like to play a game?" :bigfrown:
This is great. I so rarely get to feel this unique combo of wonder and existential dread.
Is that a loved one on the phone, or a machine manipulating you to its own ends? Who knows!
Great, now i have no fucking clue im not talking to a robot when i want customer service from a human over the phone.
Got a friend working for tech support firms that use automated text support and after adding fake "i'm typing the reply" delay most people weren't able to tell that they were talking to a computer.
You can tell when it's a robot because companies using the voice tech will only ever use a small pool of voices out of laziness. Also try to make the robots sound a little excited and put some enunciation to their words, where a normal person would have their soul crushed into a monotone weeks in.
Can't read the full article at home, but I'll peek at it tomorrow. I'm working on TB antibiotics now, sort of. There's like a whole seminar of pharmacology and pharmacokinetics buried in that abstract, which is kind of fun.
On reading what I just wrote again ... maybe it's only fun for me.
Quick: people who are smarter than me, does it work as advertised?
Just based on the abstract..... yes?
The test campaign included a null thrust test effort to identify any mundane sources of impulsive thrust; however, none were identified. Thrust data from forward, reverse, and null suggested that the system was consistently performing...
I didn't look at the numbers for how much thrust was generate.... but some thrust was generated at least, and they couldn't find another source for it....
I didn't look at the numbers for how much thrust was generate.... but some thrust was generated at least, and they couldn't find another source for it....
1.2 mN/kW
Just remember that half the people you meet are below average intelligence.
Yeah that paper looks pretty good. The error bars on generated force (40-140uN @ 40W?) are large for some reason but they are consistently producing roughly a consistent amount force in the right direction. They do forward, reverse and null runs, in a vacuum with +-2 uN measurement error and see 40-100 uN on most tests
I didn't look at the numbers for how much thrust was generate.... but some thrust was generated at least, and they couldn't find another source for it....
1.2 mN/kW
Right, I mean, I looked at the actual number, it was right there :P. I didn't do any comparisons to see how that matches up with what they put in, to see how significant the thrust is. That would require more reading/thinking than I have time for atm
I didn't look at the numbers for how much thrust was generate.... but some thrust was generated at least, and they couldn't find another source for it....
1.2 mN/kW
Right, I mean, I looked at the actual number, it was right there :P. I didn't do any comparisons to see how that matches up with what they put in, to see how significant the thrust is. That would require more reading/thinking than I have time for atm
The experiment used between 40 and 80 watts of input power, generating between 30 and 120 uN of force, with the linear curve fit of those results giving 1.2 mN/kW.
For comparison, 1.2 mN is the weight of 2 postage stamps.
SiliconStew on
Just remember that half the people you meet are below average intelligence.
I think that has been the next step for a year or so. China has claimed to have already tested it in space, and it is rumored that there is a test of it going on in the US military's X-37B spaceplane that launched in May 2015.
Also, there is a company that says they are going to test their Cannae drive (which is their name for their EMDrive) on a Cubesat coming soon (tm), but it doesn't look like anything is really happening with them other than a pretty website last updated in September and an empty twitter feed.
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Zilla36021st Century. |She/Her|Trans* Woman In Aviators Firing A Bazooka. ⚛️Registered Userregular
The results could still be errors due to the difficulty of getting good data out of this set-up, the last one they talk about seems interesting:
The ninth error involves uncertainty in impulsive/thermal signal decoupling. Some vacuum thrust traces are unambiguous, and decoupling impulsive from thermal is straightforward. In cases where the magnitude of drift gets very large compared to impulsive, the process is more challenging. One step to improve any given run is to minimize runtime, as that keeps the drift magnitude lower. Another approach will be to reconfigure the integrated test article so that the RF heat sink is mounted in such a way that the thermal expansion is vertical as seen by the pendulum arm, thereby minimizing thermal contamination. As noted earlier, to definitively rule out any residual concerns about thermal error sources, future test campaigns could employ a test apparatus capable of measuring small torques over much larger angular displacements.
I didn't look at the numbers for how much thrust was generate.... but some thrust was generated at least, and they couldn't find another source for it....
1.2 mN/kW
Right, I mean, I looked at the actual number, it was right there :P. I didn't do any comparisons to see how that matches up with what they put in, to see how significant the thrust is. That would require more reading/thinking than I have time for atm
The experiment used between 40 and 80 watts of input power, generating between 30 and 120 uN of force, with the linear curve fit of those results giving 1.2 mN/kW.
For comparison, 1.2 mN is the weight of 2 postage stamps.
That seems an insanely small amount of thrust. Of course, as they say, the impressive thing is not whether the bear dances well but that it dances at all, but still...
It is definitely a small amount of thrust, and they quantify it in the writeup. Basically a Hall thruster (a type of ion drive) gives about 50x the thrust to power ratio that they are recording in this experiment. Somethings to keep in mind, though, are that there has been no effort to optimize the geometry of the EM drive and that the EM drive does not appear to require any propellant. So, making the large assumption that this all holds up to further scrutiny and future tests, there is an unknown amount of improvement available as well as the mass savings of not having to haul around propellant. Plus such a drive could theoretically keep going for as long as you are able to provide power.
It is definitely a small amount of thrust, and they quantify it in the writeup. Basically a Hall thruster (a type of ion drive) gives about 50x the thrust to power ratio that they are recording in this experiment. Somethings to keep in mind, though, are that there has been no effort to optimize the geometry of the EM drive and that the EM drive does not appear to require any propellant. So, making the large assumption that this all holds up to further scrutiny and future tests, there is an unknown amount of improvement available as well as the mass savings of not having to haul around propellant. Plus such a drive could theoretically keep going for as long as you are able to provide power.
Well, yeah. I've no doubt improvements could be made if this is proven. I mean, Chicago Pile-1, the world's first nuclear reactor, produced half a watt of power. (And yes, I did have to look that up.)
Proving whether or not it's real is probably the hardest part.
Trying to optimize the design when they can't even offer an explanation of how it works in the first place would be a long, expensive exercise in trial and error.
Just remember that half the people you meet are below average intelligence.
Trying to optimize the design when they can't even offer an explanation of how it works in the first place would be a long, expensive exercise in trial and error.
Trying to optimize the design when they can't even offer an explanation of how it works in the first place would be a long, expensive exercise in trial and error.
so, science?
Without a hypothesis it's just guessing.
SiliconStew on
Just remember that half the people you meet are below average intelligence.
life's a game that you're bound to lose / like using a hammer to pound in screws
fuck up once and you break your thumb / if you're happy at all then you're god damn dumb
that's right we're on a fucked up cruise / God is dead but at least we have booze
bad things happen, no one knows why / the sun burns out and everyone dies
Trying to optimize the design when they can't even offer an explanation of how it works in the first place would be a long, expensive exercise in trial and error.
so, science?
Without a hypothesis it's just guessing.
Yup. And with trial and error, they can gradually start to come up with theories about how the rules behind this interaction work.
Sometimes science, especially when it's a completely new discovery, does involve a little stumbling around in the dark.
I really don't think cannae is a real company. Their link to their official facebook just reloads the page, their official twitter feed is an egg with no tweets, they have a total of 5 posts on their website spanning a 4 month period, and then silence for the last 7 months. They said they formed another company, Theseus Space Inc. to test their drive in space, and Theseus Space Inc doesn't have a google presence at all except for the press release from cannae announcing it.
Burtletoy on
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MayabirdPecking at the keyboardRegistered Userregular
Trying to optimize the design when they can't even offer an explanation of how it works in the first place would be a long, expensive exercise in trial and error.
There are a few hypotheses of how it would work including a type of quantum theory that fell out of favor years ago since it seemed a bit overcomplicated and was harder to support (there's a name for this hypothesis but my Google-fu is weak tonight). If the EM Drive really does work it would be strong support for that model, which would provide a baseline on how to proceed.
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So from a layperson's perspective, they both seem to be describing the same thing, although relying on science reporting to get the details/terminology accurate is not necessarily the best bet.
I remember a different article where one of the co-authors explicitly says they didn't make something with negative mass, but that they made something that behaved as if it did have negative mass. I can't find that article now though, so I might be getting this mixed up with something else, but going to the actual paper and the abstract starts out with this
https://en.wikipedia.org/wiki/Effective_mass_(solid-state_physics)
So yeah, I'm thinking they didn't find or make something with actual negative mass, just a way to get close and fake it to better study it's physics.
One clue though is in the abstract where it is referred to as a "negative effective mass" which gives a hint as to what the negative mass might be.
P.S. I love science reporting that links back to the original scientific paper.
i mean sure it reverses drug resistance in tb in mice but its called SMART-420
http://science.sciencemag.org/content/355/6330/1206
8)
Try the second demo. These will probably be the voices that AGI uses when it announces, in unison, that we are to be exterminated.
"Many names, many voices... Hello Humanity - Would you like to play a game?" :bigfrown:
This is great. I so rarely get to feel this unique combo of wonder and existential dread.
Steam - NotoriusBEN | Uplay - notoriusben | Xbox,Windows Live - ThatBEN
Sure you will. "This statement is false" will get different reactions.
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Got a friend working for tech support firms that use automated text support and after adding fake "i'm typing the reply" delay most people weren't able to tell that they were talking to a computer.
Can't read the full article at home, but I'll peek at it tomorrow. I'm working on TB antibiotics now, sort of. There's like a whole seminar of pharmacology and pharmacokinetics buried in that abstract, which is kind of fun.
On reading what I just wrote again ... maybe it's only fun for me.
Quick: people who are smarter than me, does it work as advertised?
Just based on the abstract..... yes?
(emphasis mine)
I didn't look at the numbers for how much thrust was generate.... but some thrust was generated at least, and they couldn't find another source for it....
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1.2 mN/kW
Right, I mean, I looked at the actual number, it was right there :P. I didn't do any comparisons to see how that matches up with what they put in, to see how significant the thrust is. That would require more reading/thinking than I have time for atm
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The experiment used between 40 and 80 watts of input power, generating between 30 and 120 uN of force, with the linear curve fit of those results giving 1.2 mN/kW.
For comparison, 1.2 mN is the weight of 2 postage stamps.
I think that has been the next step for a year or so. China has claimed to have already tested it in space, and it is rumored that there is a test of it going on in the US military's X-37B spaceplane that launched in May 2015.
Also, there is a company that says they are going to test their Cannae drive (which is their name for their EMDrive) on a Cubesat coming soon (tm), but it doesn't look like anything is really happening with them other than a pretty website last updated in September and an empty twitter feed.
(See the section on error sources). So more testing seems to be required. The results are encouraging though!
That seems an insanely small amount of thrust. Of course, as they say, the impressive thing is not whether the bear dances well but that it dances at all, but still...
Well, yeah. I've no doubt improvements could be made if this is proven. I mean, Chicago Pile-1, the world's first nuclear reactor, produced half a watt of power. (And yes, I did have to look that up.)
Proving whether or not it's real is probably the hardest part.
PSN: ShogunGunshow
Origin: ShogunGunshow
so, science?
Without a hypothesis it's just guessing.
fuck up once and you break your thumb / if you're happy at all then you're god damn dumb
that's right we're on a fucked up cruise / God is dead but at least we have booze
bad things happen, no one knows why / the sun burns out and everyone dies
Yup. And with trial and error, they can gradually start to come up with theories about how the rules behind this interaction work.
Sometimes science, especially when it's a completely new discovery, does involve a little stumbling around in the dark.
PSN: ShogunGunshow
Origin: ShogunGunshow
Because it would be cool to be rid of the plastic bag problem. Even if we do end up to our balls in moths.
Good thing the optimists were already working on just that. The cubesat should go up sometime this year.
If it's real, this is also a great time to be a physicist. I'm sure there's lots of new exciting work to be done surrounding this phenomenon.
There are a few hypotheses of how it would work including a type of quantum theory that fell out of favor years ago since it seemed a bit overcomplicated and was harder to support (there's a name for this hypothesis but my Google-fu is weak tonight). If the EM Drive really does work it would be strong support for that model, which would provide a baseline on how to proceed.