Oh for fuck's sake... Time to debunk this shit, again. TFA got it wrong as well, so I suppose I can't blame you people for getting it wrong too, but please try doing a little more research? A little background: The EmDrive was invented by a guy named Shawyer.
I have have a copy of the paper in question, "Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum," and have read it in detail. It does not reference Shawyer. This paper is not about the "EmDrive."
It was tested by NASA, among others, and found to produce about 91 microNewtons. (I'll address the 30-50 that TFA talks about too.) That's way less than the Chinese found, but NASA was also testing it at much lower power and say they are planning to test a higher-power version.
"Way less" means "over four orders of magnitude less." The Juan et al. test-- reference 1 in the paper-- did not test a thruster at hundreds of kilowatts input power! At best, you can say that the JSC test was testing something different form the Chinese test. They did not replicate the Chinese tests in any way.
...To test this, two versions of the Cannae Drive were (also, separately from the EmDrive test) tested by NASA: one with and one without the slots. Those tests both produced the same thrust (30-50 microN, about half what the EmDrive produced), which disproves Fetta's theory as to how the Cannae Drive is supposed to work.... and nothing else The null test device that everybody is so dismissedly claiming claiming disproves the EmDrive wasn't even supposed to be an EmDrive!
The EmDrive was not mentioned or referenced in the paper being discussed.
Fetta, inventor of the Cannae Drive, was disproven.
Correct. This is a valid conclusion of the results of the paper.
Shawyer, inventor of the EmDrive, was actually vindicated because according to his theory, the Cannae Drive (slots or no) is basically an inefficiently-shaped EmDrive.
Shawyer was not mentioned nor referenced in the paper. The EmDrive was not mentioned nor referenced in the paper.
I don't know why this is so hard for people to understand.
It is hard for people to understand because in an article about the results of a paper "Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum," you reference a garbage-dumpster full of other stuff that is not mentioned nor referenced in that paper.
Any 2nd year physics student should be able to laugh this garbage right off a lab bench without even running an experiment.
And laughing this off without even running an experiment is precisely the wrong thing to do.
Science is about replication. Replication requires doing the experiment. Or, at a minimum, not laughing at other people who do the experiment.
Now: the actual results of the experiment are pretty minor. The results they show, first, didn't replicate the results that they were attempting to verify, second, falsify the hypothesis that they were testing, and, third, are pretty low in magnitude-- probably spurious, in my (professional*) opinion.
The article explains why any good scientist should be able to laugh this off based on the reported experimental results.
Exactly.
This is the way science is done: you test stuff. You present your results. Other scientists then critique the results, point out flaws and sources of noise and bias.
It's rather brutal, actually. But if your result holds up to the criticisms (and most don't), maybe you've pushed the boundaries of science.
These results don't-- yet. They are not yet reporting consistent results (in that their results differ significantly from those of other researchers). They have not yet eliminated possible spurious effects.
"The Wikimedia Foundation this morning reports that 50 links to Wikipedia from Google have been removed under Europe's "right to be forgotten" regulations,..."
Looking at the Wikipedia page listing the notifications they've received of pages removed from the european search engine https://wikimediafoundation.or... , two were english wikipedia, two wre italian, and the remainder are all nl.wikipedia-- Netherlands.
So, apparently the Dutch have much more desire to be forgotten than the rest of Europe. (Or else, possibly, they're just more efficient at getting the right-to-be-forgotten notices out)
They have the pad at SLC-4 at Vandenberg to launch to polar orbits. http://www.space.com/23023-spa... And there's not much in the way of large commercial satellites in polar orbit anyway-- it's the GEO comsat market they're after with this launch site, I think.
The big deal isn't the amount of extra orbital velocity you get from the equator, it's the inclination of the resultant orbit - inclination changes *really* cut into your delta-V budget, so if you're launching into an uninclined orbit you really want to be doing it from the equator coz otherwise you have to expend a lot of fuel correcting your inclination.
Partly true-- but orbital inclination changes get easier the higher you go. It's hard to launch into low equatorial orbit from high latitudes... but nobody goes to low equatorial orbit. The higher it is, the more impulse you're putting into simply getting altitude, and the less impulse is needed for plane change.
If you're launching from the surface, the delta-V for the plane change to get an geosynchronous orbit into the equatorial plane is remarkably small.
Typically financial disclosures, such as the ones covered by OGE Form 450 (Confidential Financial Disclosure Report), are not public information and are exempted from FOIA requests
The form in question isn't the 450, which is confidential (hence its name). It's form 278, "Public Financial Disclosure", which is public (hence its name. From http://www.oge.gov/Financial-D...
Public Financial Disclosure
The Ethics in Government Act of 1978, as amended, requires senior officials in the executive, legislative and judicial branches to file public reports of their finances as well as other interests outside the Government. The statute and the U.S. Office of Government Ethics's (OGE) regulations specify which officials in the executive branch file an OGE Form 278. Unlike confidential financial statements filed by some mid-level employees, the OGE 278 is available to the public. Reviewing officials within each agency certify and maintain these reports. Agencies do, however, forward reports of Presidential appointees confirmed by the Senate and certain other reports to OGE for additional review and certification.
So they can photograph wheel tracks on the moons surface? It should then be a snap (pun intended) to take a pic of the Apollo 11 landing site and put that conspiracy to rest once and for all.
Uh, you think that people will believe that the entire moon landing program was faked, a hoax going on from 1968 (Apollo 8) through 1972 (Apollo 17), with tens of thousands of photographs, live television, and movies; with hundreds of thousands of people involved, and watched in minute detail by a hostile superpower (the USSR) that was ready to devote its entire resources to discrediting America... but you think these same people would instantly believe a photograph from Lunar Reconaissance Orbiter, because satellite photos can't be faked?
So the channel itself... has the diffraction, scattering, and beam spread of an unchanneled beam.
The beams making the channel are channeled by themselves, they create filaments that self-focus the beam. Self-focusing beams in air have been pretty well established at this point and will go quite far if you have enough power because of the attenuation involved.
So, what you just said is that the beams self-channel anyway.
So, if beams self-channel, this innovation does nothing, right? It's a complicated system of multiple beams to make the beam channel, which is to say, self-focus. But you just told me "self-focusing beams in air have been pretty well established at this point."
To the extent that air is not transparent, this doesn't work.
and does cause beam scattering.
This does not address beam scattering. If the air is scattering the laser beam, it still scatters the beam.
by creating a refractive channel like this they absolutely will reduce beam dispersion.
It would reduce beam spread... except that the beams that create the channel are not themselves channeled.
obviously it doesn't eliminate beam spread
on this we agree
but even a fiber channel perfectly designed for a single mode will have some diffusion so whats your point?
My point is that from a surface-level analysis, it doesn't do anything useful.
they may be able to increase snr by 10^4 over current technologies at 100 m. that's a serious improvement that shouldn't simply be dismissed so thoughtlessly.
Let me repeat. The beams that create the channel are not themselves channeled. So the channel itself... has the diffraction, scattering, and beam spread of an unchanneled beam. The net result can't be better than an unchanneled beam, because it is made out of an unchanneled beam.
I'm puzzled as to what this does or what it's good for, exactly.
... they have turned thin air into an "optical fiber" that can transmit and amplify light signals without the need for any cables.
1. Air already transmits light signals. It's transparent. 2. They haven't mentioned anything about amplifying light signals. This would be hard.
So, they are creating a "pipe" that can transmit light... but it doesn't stop beam spread (since the beams that make up the "pipe" still have diffraction-limited beam spread), and it can't bend light around corners. So, they now have a pipe that will funnel a laser beam along the path made by other laser beams, which take it exactly the same path that the beam would go without the pipe...
I might be made fun of for this but I'll ask anyway: If negative mass could be practically harnessef, would it allow for the antigravity/repulsorlift/mass effect technology of science fiction to be real?
Well, if you load your positive-mass vehicle up with an amount of negative mass, it will still fall downward, but it will have less overall mass and less weight. So it will only take a little amount of force to lift it or move it around.
The "if negative mass could be practically harnessed" is a big "if," though. Even aside from the fact that you have to figure out how to make negative mass.
Negative mass reacts oppositely to both gravity and intertia. Oddly, that means that negative mass still falls down in a gravitational field: The gravitational force is opposite, but negative mass responds negatively to force (a=F/m, where both F and m are negative). So negative mass particles repel each other gravitationally, but are attracted to positive mass objects.
Right
In other words, unlike normal matter, negative mass matter can never lump together under influence of gravitational force,
Right
but it will nevertheless attract normal matter.
You'd think, if it behaved like ordinary matter, that if it is attracted to positive matter, than it would conversely also attract positive matter. But no.
Negative matter particles attract each other, as you say, but repel normal matter. (They're attracted to it... but they repel it.)
principle. IANA physicist, but I've never been happy with this here thingy.
Fortunately, your happiness is not relevant to whether physics works.
... Oh, BTW - this is just one of many examples where science does, in fact, depend on pure faith.
No, this is one of the many examples where science depends on pure observation. The Pauli exclusion principle was first arrived at from observations, and only somewhat later was the theoretical basis-- the spin-statistics theorem-- worked out.
Out of interest, if there were pair creation events of involving particles of negative mass/gravity how would we detect them?
You're asking a lot, since we don't really know what the property of the particles are. A negative mass particle would curve in electric and magnetic fields (the usual way to determine what a particle is) just like a positive mass particle of the opposite charge. However, since negative mass particles also have negative kinetic energy, conservation of energy means that the remaining particles will have more energy coming out of the collision than they did going into it.
I'm not being critical, I'm curious - how would a particle accelerator, or a bubble chamber or whatever, look different with a negative mass particle?
Positive mass particles emit positive energy and slow down. Negative mass particles emit positive energy and speed up. If you see unknown particles exiting the scene at high velocity, and leaving behind more energy the faster they go, that would be a negative mass particle.
What's supposed to happen when negative and positive mass collide?
If I throw a tennis ball at a wall, it bounces off (and the wall recoils imperceptibly). If I throw a negative tennis ball at a wall -- or throw it away, causing it to move toward the wall, whatever -- what happens when it hits? It seems like it would try to "recoil" in the same direction it was traveling, maybe even giving the wall a "tug" instead of a "push" when it hit. \
Well, I already said negative matter is weird.
Robert Forward proposed that when positive matter and negative matter touch, they cancel each other out, and vanish:
(+) + (-) --> 0 (vacuum) The mass cancels, and you're left with nothing there.
Unfortunately, we know that this can't happen, because if it did, then the opposite reaction could occur:
0 --> (+) + (-) --vacuum spontaneously generating pairs of positive and negative mass. If this could happen, it would happen, everywhere, all the time. But it doesn't. So there are rules (presumably conservation laws) forbidding this from occurring.
But it can't move forward, because presumably negative and positive matter can't simply interpenetrate -- or can they?
Of course they can interpenetrate. The reason that you can't walk through a brick wall is because of Pauli exclusion: the electrons in your body can't occupy the same place (the same quantum state) as the electrons in the wall. But, whatever negative matter is, it's not electrons (nor any of the other particles that make up "solid" matter). So, yes, it would pass right through ordinary matter.
What you're pointing out -- that a positive mass and a negative mass would chase each other-- was pointed out in 1957 in Bondi's paper about negative mass, "Negative Mass in General Relativity". Rev. Mod. Phys. 29 (3). Robert Forward, in 1990, then extended that analysis even further and pointed out that negative mass is even weirder than that.
A negative mass chasing a positive mass accelerates forever... but it doesn't violate conservation of energy, because the faster a negative mass moves, the more negative the kinetic energy, so the positive kinetic energy and the negative kinetic energy cancel out, leaving energy conserved.
There are weirder things than that, too.
If you think this is so weird that bulk negative mass can't exist... well, that's what Einstein thought (the "positive energy condition").
Is this similar to, unrelated to, part of, dissimilar, orthogonal, integral, or in any way linked to Dark Matter?
It's unrelated to dark matter (which has positive mass- that's how we know it's there), but dark energy is gravitationally negative (it causes expansion to accelerate: it's gravitationally repulsive)
Because I (and probably most of us) don't understand that either.
You're in good company! If you did understand it, you could publish, and you should be getting a phone call from Stockholm soon.
Negative mass is very diferent from antimatter. Antimatter is opposite to normal matter in charge and quantum numbers (such as baryon number, etc.), but still has positive mass.
Negative mass reacts oppositely to both gravity and intertia. Oddly, that means that negative mass still falls down in a gravitational field: The gravitational force is opposite, but negative mass responds negatively to force (a=F/m, where both F and m are negative). So negative mass particles repel each other gravitationally, but are attracted to positive mass objects.
This has peculiar consequences. One consequence is that, for objects of negative mass, gravity and electrostatic charge switch. For normal mass objects, gravity is attractive, but like electrical charges repel. For negative matter, gravity is repulsive, but like electrical charges attract.
I wrote about this once, in the AIAA Journal of Propulsion and Power-- not a journal that physicists usually read, I'm afraid. If you have access to AIAA online, it's here: http://arc.aiaa.org/doi/pdf/10...
It seems to me that NASA should simply contract those basic research payloads on top of SpaceX rockets, if SpaceX can get them into orbit for fewer dollars than NASA's own internal teams can. Why waste resources?
That's the way NASA currently does business: launch services are purchased.
SpaceX developed Falcon-9 on a NASA contract, specifically in order to be a vehicle that can be purchased for launch services. ("Commercial Orbital Transportation Services" was the name of the contract.)
While fast radio bursts last just a few thousandths of a second and have rarely been detected, the new result confirms previous estimates that these strange cosmic bursts occur roughly 10,000 times a day over the whole sky.
It's worth pointing out that a good way to send a signal would be to have a bright but transient beacon, which doesn't itself transmit information (other than "here I am"), but serves to tell others where to point their high-gain radiotelescopes.
This could be what such a beacon would look like.
Not to mention the power output it would need to send a detectible signal from another galaxy.
From the summary: "bright flashes of radio waves that last only a few thousandths of a second.
A high power for a few milliseconds may not take an enormous amount of energy.
Slashdot Mirror
Oh for fuck's sake... Time to debunk this shit, again.
TFA got it wrong as well, so I suppose I can't blame you people for getting it wrong too, but please try doing a little more research?
A little background: The EmDrive was invented by a guy named Shawyer.
I have have a copy of the paper in question, "Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum," and have read it in detail. It does not reference Shawyer. This paper is not about the "EmDrive."
It was tested by NASA, among others, and found to produce about 91 microNewtons. (I'll address the 30-50 that TFA talks about too.) That's way less than the Chinese found, but NASA was also testing it at much lower power and say they are planning to test a higher-power version.
"Way less" means "over four orders of magnitude less." The Juan et al. test-- reference 1 in the paper-- did not test a thruster at hundreds of kilowatts input power! At best, you can say that the JSC test was testing something different form the Chinese test. They did not replicate the Chinese tests in any way.
...To test this, two versions of the Cannae Drive were (also, separately from the EmDrive test) tested by NASA: one with and one without the slots. Those tests both produced the same thrust (30-50 microN, about half what the EmDrive produced), which disproves Fetta's theory as to how the Cannae Drive is supposed to work.... and nothing else The null test device that everybody is so dismissedly claiming claiming disproves the EmDrive wasn't even supposed to be an EmDrive!
The EmDrive was not mentioned or referenced in the paper being discussed.
Fetta, inventor of the Cannae Drive, was disproven.
Correct. This is a valid conclusion of the results of the paper.
Shawyer, inventor of the EmDrive, was actually vindicated because according to his theory, the Cannae Drive (slots or no) is basically an inefficiently-shaped EmDrive.
Shawyer was not mentioned nor referenced in the paper. The EmDrive was not mentioned nor referenced in the paper.
I don't know why this is so hard for people to understand.
It is hard for people to understand because in an article about the results of a paper "Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum," you reference a garbage-dumpster full of other stuff that is not mentioned nor referenced in that paper.
And laughing this off without even running an experiment is precisely the wrong thing to do.
Science is about replication. Replication requires doing the experiment. Or, at a minimum, not laughing at other people who do the experiment.
Now: the actual results of the experiment are pretty minor. The results they show, first, didn't replicate the results that they were attempting to verify, second, falsify the hypothesis that they were testing, and, third, are pretty low in magnitude-- probably spurious, in my (professional*) opinion.
The article explains why any good scientist should be able to laugh this off based on the reported experimental results.
Exactly.
This is the way science is done: you test stuff. You present your results. Other scientists then critique the results, point out flaws and sources of noise and bias.
It's rather brutal, actually. But if your result holds up to the criticisms (and most don't), maybe you've pushed the boundaries of science.
These results don't-- yet. They are not yet reporting consistent results (in that their results differ significantly from those of other researchers). They have not yet eliminated possible spurious effects.
That's science.
---
*in fact, I am a rocket scientist
"The Wikimedia Foundation this morning reports that 50 links to Wikipedia from Google have been removed under Europe's "right to be forgotten" regulations,..."
Looking at the Wikipedia page listing the notifications they've received of pages removed from the european search engine https://wikimediafoundation.or... , two were english wikipedia, two wre italian, and the remainder are all nl.wikipedia-- Netherlands.
So, apparently the Dutch have much more desire to be forgotten than the rest of Europe. (Or else, possibly, they're just more efficient at getting the right-to-be-forgotten notices out)
I'm on my way to yelp to post a review of them right now.
1) can't launch to polar orbit.
They have the pad at SLC-4 at Vandenberg to launch to polar orbits.
http://www.space.com/23023-spa...
And there's not much in the way of large commercial satellites in polar orbit anyway-- it's the GEO comsat market they're after with this launch site, I think.
The big deal isn't the amount of extra orbital velocity you get from the equator, it's the inclination of the resultant orbit - inclination changes *really* cut into your delta-V budget, so if you're launching into an uninclined orbit you really want to be doing it from the equator coz otherwise you have to expend a lot of fuel correcting your inclination.
Partly true-- but orbital inclination changes get easier the higher you go. It's hard to launch into low equatorial orbit from high latitudes... but nobody goes to low equatorial orbit. The higher it is, the more impulse you're putting into simply getting altitude, and the less impulse is needed for plane change.
If you're launching from the surface, the delta-V for the plane change to get an geosynchronous orbit into the equatorial plane is remarkably small.
Typically financial disclosures, such as the ones covered by OGE Form 450 (Confidential Financial Disclosure Report), are not public information and are exempted from FOIA requests
The form in question isn't the 450, which is confidential (hence its name). It's form 278, "Public Financial Disclosure", which is public (hence its name.
From http://www.oge.gov/Financial-D...
Public Financial Disclosure
The Ethics in Government Act of 1978, as amended, requires senior officials in the executive, legislative and judicial branches to file public reports of their finances as well as other interests outside the Government. The statute and the U.S. Office of Government Ethics's (OGE) regulations specify which officials in the executive branch file an OGE Form 278. Unlike confidential financial statements filed by some mid-level employees, the OGE 278 is available to the public. Reviewing officials within each agency certify and maintain these reports. Agencies do, however, forward reports of Presidential appointees confirmed by the Senate and certain other reports to OGE for additional review and certification.
So they can photograph wheel tracks on the moons surface? It should then be a snap (pun intended) to take a pic of the Apollo 11 landing site and put that conspiracy to rest once and for all.
Uh, you think that people will believe that the entire moon landing program was faked, a hoax going on from 1968 (Apollo 8) through 1972 (Apollo 17), with tens of thousands of photographs, live television, and movies; with hundreds of thousands of people involved, and watched in minute detail by a hostile superpower (the USSR) that was ready to devote its entire resources to discrediting America... but you think these same people would instantly believe a photograph from Lunar Reconaissance Orbiter, because satellite photos can't be faked?
The moon is not another planet. The JPL site has the correct information.
The headline has the correct phrasing: the rover has set the off-world driving record.
So the channel itself... has the diffraction, scattering, and beam spread of an unchanneled beam.
The beams making the channel are channeled by themselves, they create filaments that self-focus the beam. Self-focusing beams in air have been pretty well established at this point and will go quite far if you have enough power because of the attenuation involved.
So, what you just said is that the beams self-channel anyway.
So, if beams self-channel, this innovation does nothing, right? It's a complicated system of multiple beams to make the beam channel, which is to say, self-focus. But you just told me "self-focusing beams in air have been pretty well established at this point."
air is not transparent
To the extent that air is not transparent, this doesn't work.
and does cause beam scattering.
This does not address beam scattering. If the air is scattering the laser beam, it still scatters the beam.
by creating a refractive channel like this they absolutely will reduce beam dispersion.
It would reduce beam spread... except that the beams that create the channel are not themselves channeled.
obviously it doesn't eliminate beam spread
on this we agree
but even a fiber channel perfectly designed for a single mode will have some diffusion so whats your point?
My point is that from a surface-level analysis, it doesn't do anything useful.
they may be able to increase snr by 10^4 over current technologies at 100 m. that's a serious improvement that shouldn't simply be dismissed so thoughtlessly.
Let me repeat. The beams that create the channel are not themselves channeled. So the channel itself... has the diffraction, scattering, and beam spread of an unchanneled beam. The net result can't be better than an unchanneled beam, because it is made out of an unchanneled beam.
I'm puzzled as to what this does or what it's good for, exactly.
... they have turned thin air into an "optical fiber" that can transmit and amplify light signals without the need for any cables.
1. Air already transmits light signals. It's transparent.
2. They haven't mentioned anything about amplifying light signals. This would be hard.
So, they are creating a "pipe" that can transmit light... but it doesn't stop beam spread (since the beams that make up the "pipe" still have diffraction-limited beam spread), and it can't bend light around corners. So, they now have a pipe that will funnel a laser beam along the path made by other laser beams, which take it exactly the same path that the beam would go without the pipe...
Right.
That was pointed out by Bondi in his 1957 paper introducing the concept.
http://journals.aps.org/rmp/ab...
I might be made fun of for this but I'll ask anyway: If negative mass could be practically harnessef, would it allow for the antigravity/repulsorlift/mass effect technology of science fiction to be real?
Well, if you load your positive-mass vehicle up with an amount of negative mass, it will still fall downward, but it will have less overall mass and less weight. So it will only take a little amount of force to lift it or move it around.
The "if negative mass could be practically harnessed" is a big "if," though. Even aside from the fact that you have to figure out how to make negative mass.
Not so fast! Let me quote the GP:
Negative mass reacts oppositely to both gravity and intertia. Oddly, that means that negative mass still falls down in a gravitational field: The gravitational force is opposite, but negative mass responds negatively to force (a=F/m, where both F and m are negative). So negative mass particles repel each other gravitationally, but are attracted to positive mass objects.
Right
In other words, unlike normal matter, negative mass matter can never lump together under influence of gravitational force,
Right
but it will nevertheless attract normal matter.
You'd think, if it behaved like ordinary matter, that if it is attracted to positive matter, than it would conversely also attract positive matter. But no.
Negative matter particles attract each other, as you say, but repel normal matter. (They're attracted to it... but they repel it.)
The equations are: F = ma
and F = G mM/r^2
Ah, the
Pauli exclusion
principle. IANA physicist, but I've never been happy with this here thingy.
Fortunately, your happiness is not relevant to whether physics works.
...
Oh, BTW - this is just one of many examples where science does, in fact, depend on pure faith.
No, this is one of the many examples where science depends on pure observation. The Pauli exclusion principle was first arrived at from observations, and only somewhat later was the theoretical basis-- the spin-statistics theorem-- worked out.
Out of interest, if there were pair creation events of involving particles of negative mass/gravity how would we detect them?
You're asking a lot, since we don't really know what the property of the particles are. A negative mass particle would curve in electric and magnetic fields (the usual way to determine what a particle is) just like a positive mass particle of the opposite charge. However, since negative mass particles also have negative kinetic energy, conservation of energy means that the remaining particles will have more energy coming out of the collision than they did going into it.
I'm not being critical, I'm curious - how would a particle accelerator, or a bubble chamber or whatever, look different with a negative mass particle?
Positive mass particles emit positive energy and slow down. Negative mass particles emit positive energy and speed up. If you see unknown particles exiting the scene at high velocity, and leaving behind more energy the faster they go, that would be a negative mass particle.
Okay, as long as I've got you on the line... :)
What's supposed to happen when negative and positive mass collide?
If I throw a tennis ball at a wall, it bounces off (and the wall recoils imperceptibly). If I throw a negative tennis ball at a wall -- or throw it away, causing it to move toward the wall, whatever -- what happens when it hits? It seems like it would try to "recoil" in the same direction it was traveling, maybe even giving the wall a "tug" instead of a "push" when it hit. \
Well, I already said negative matter is weird.
Robert Forward proposed that when positive matter and negative matter touch, they cancel each other out, and vanish:
(+) + (-) --> 0 (vacuum)
The mass cancels, and you're left with nothing there.
Unfortunately, we know that this can't happen, because if it did, then the opposite reaction could occur:
0 --> (+) + (-)
--vacuum spontaneously generating pairs of positive and negative mass. If this could happen, it would happen, everywhere, all the time. But it doesn't. So there are rules (presumably conservation laws) forbidding this from occurring.
But it can't move forward, because presumably negative and positive matter can't simply interpenetrate -- or can they?
Of course they can interpenetrate. The reason that you can't walk through a brick wall is because of Pauli exclusion: the electrons in your body can't occupy the same place (the same quantum state) as the electrons in the wall. But, whatever negative matter is, it's not electrons (nor any of the other particles that make up "solid" matter). So, yes, it would pass right through ordinary matter.
What am I missing?
Nothing. Negative mass is weird.
What you're pointing out -- that a positive mass and a negative mass would chase each other-- was pointed out in 1957 in Bondi's paper about negative mass, "Negative Mass in General Relativity". Rev. Mod. Phys. 29 (3). Robert Forward, in 1990, then extended that analysis even further and pointed out that negative mass is even weirder than that.
A negative mass chasing a positive mass accelerates forever... but it doesn't violate conservation of energy, because the faster a negative mass moves, the more negative the kinetic energy, so the positive kinetic energy and the negative kinetic energy cancel out, leaving energy conserved.
There are weirder things than that, too.
If you think this is so weird that bulk negative mass can't exist... well, that's what Einstein thought (the "positive energy condition").
Is this similar to, unrelated to, part of, dissimilar, orthogonal, integral, or in any way linked to Dark Matter?
It's unrelated to dark matter (which has positive mass- that's how we know it's there), but dark energy is gravitationally negative (it causes expansion to accelerate: it's gravitationally repulsive)
Because I (and probably most of us) don't understand that either.
You're in good company! If you did understand it, you could publish, and you should be getting a phone call from Stockholm soon.
What ever happened to Occam's Razor?
It competes with the totalitarian principle, "everything that is not forbidden is compulsory."
Negative mass is very diferent from antimatter. Antimatter is opposite to normal matter in charge and quantum numbers (such as baryon number, etc.), but still has positive mass.
Negative mass reacts oppositely to both gravity and intertia. Oddly, that means that negative mass still falls down in a gravitational field: The gravitational force is opposite, but negative mass responds negatively to force (a=F/m, where both F and m are negative). So negative mass particles repel each other gravitationally, but are attracted to positive mass objects.
This has peculiar consequences. One consequence is that, for objects of negative mass, gravity and electrostatic charge switch. For normal mass objects, gravity is attractive, but like electrical charges repel. For negative matter, gravity is repulsive, but like electrical charges attract.
I wrote about this once, in the AIAA Journal of Propulsion and Power-- not a journal that physicists usually read, I'm afraid. If you have access to AIAA online, it's here: http://arc.aiaa.org/doi/pdf/10...
It seems to me that NASA should simply contract those basic research payloads on top of SpaceX rockets, if SpaceX can get them into orbit for fewer dollars than NASA's own internal teams can. Why waste resources?
That's the way NASA currently does business: launch services are purchased.
SpaceX developed Falcon-9 on a NASA contract, specifically in order to be a vehicle that can be purchased for launch services. ("Commercial Orbital Transportation Services" was the name of the contract.)
While fast radio bursts last just a few thousandths of a second and have rarely been detected, the new result confirms previous estimates that these strange cosmic bursts occur roughly 10,000 times a day over the whole sky.
That's a lot of aliens.
Well, since there are 100 to 200 billion galaxies in the observable universe, not so many. One burst per galaxy every 50,000 years or so.
Or maybe we are inside of a slow thinking alien's head.
It's worth pointing out that a good way to send a signal would be to have a bright but transient beacon, which doesn't itself transmit information (other than "here I am"), but serves to tell others where to point their high-gain radiotelescopes.
This could be what such a beacon would look like.
Not to mention the power output it would need to send a detectible signal from another galaxy.
From the summary: "bright flashes of radio waves that last only a few thousandths of a second.
A high power for a few milliseconds may not take an enormous amount of energy.