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Cosmologists Show Negative Mass Could Exist In Our Universe
KentuckyFC (1144503) writes The idea of negative mass has fascinated scientists since it was first used in the 16th century to explain why metals gain weight when they are oxidized. Since then, theoretical physicists have shown how it could be used to create exotic objects such as wormholes and the Alcubierre warp drive. But cosmologists' attempts to include negative matter in any reasonable model of the cosmos have always run into trouble because negative mass violates the energy conditions required to make realistic universes with Einstein's theory of general relativity. Now a pair of cosmologists have found a way around this. By treating negative mass as a perfect fluid rather than a solid point-like object, they've shown that negative mass does not violate the energy conditions as had been thought, and so it must be allowed in our universe. That has important consequences. If positive and negative mass particles were created in the early universe, they would form a kind of plasma that absorbs gravitational waves. Having built a number of gravitational wave observatories that have to see a single gravitational wave, astronomers might soon need to explain the absence of observations. Negative mass would then come in extremely handy.
The summary makes mention that we haven't noted any substantial signs of this material, but how is that any different from, say, antimatter, which we know can exist?
The summary makes mention that we haven't noted any substantial signs of this material, but how is that any different from, say, antimatter, which we know can exist?
Not too long ago, I think we even created an anti-hydrogen atom.
Negative mass? Not so much (yet).
wrong
As I understood it with my very limited knowledge of physics, there are perceivable phenomena that did not quite make sense because it was an either/or situation.
In that case, Occam's Razor makes way for Sherlock Holmes' "Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."
A model that allows for more of the perceived phenomena than previous models must be taken under more scrutiny.
As we better understand the universe, we find gaps between reality and our understanding. We then try to extend our understanding to better match reality, and that means filling in those gaps. Sometimes it takes many tries to fill in a gap, or at least make it smaller.
Negative mass is one of those attempts, and it's worth noting that they aren't clinging to the concept, they're simply suggesting that it's one possibility that can be tested. In other words, they actually are using Occam's Razor. In this realm, nothing is simple, which makes the Razor harder to use.
The living have better things to do than to continue hating the dead.
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...
http://www.geoffreylandis.com
A goal for all those zero sized models and weight loss fanatics to aim for!
What ever happened to Occam's Razor?
It competes with the totalitarian principle, "everything that is not forbidden is compulsory."
http://www.geoffreylandis.com
"Not even wrong."
This kind of subject always leads to a cascade of stupid questions in my head that I can't answer, leaving me feeling even dumber than usual. Does negative mass necessarily imply negative weight? What about momentum and kinetic energy? If a lump of matter with negative mass hit something, would it actually absorb energy from it rather than imparting energy to it? Would a negative-mass planet have an anti-gravity field? Is it even meaningful to talk about matter with negative mass, or is some physicist going to pop up and explain to me that negative mass is a property of some sort of field, and not something that could actually be expressed by anything that I would recognise as matter?
Oh no... it's the future.
If they must see that same single gravitational wave over and over again, why do we need to keep building more of them? Why don't we build some to see OTHER gravitational waves?
This is not a fantasy it is a useful result. Previously it was thought that negative mass was fundamentally incompatible with GR i.e. you could not have negative mass in our universe according to one of our most fundamental theories. This result, if confirmed, suggests that actually you can have negative mass in a way that is compatible with GR.
It is important to note that this does NOT mean that negative mass exists, only that, so far as we know, it could exist. All it means is that it is now another possible tool in the theorists arsenal to explain experimental observations without rewriting GR. However if I were to apply Occam's Razor to this discovery then I would argue that if something is allowed by GR we would expect it to be possible to produce because otherwise you need some additional mechanism beyond GR to prevent it from existing. Hence the simpler model is one where negative mass can exist...not that this means that it does. We are talking theoretical possibilities here, not experimental observations.
Science is about generating hypotheses, then determining which are incorrect. Many things we take for granted in science now sounded too fantastic to believe when they were proposed. Quantum physics, plate tectonics, and ulcers caused by h. pylori are three examples that come to mind. On the other hand, you shouldn't blindly believe any new hypothesis just because you like it -- you should demand evidence before you accept a new idea.
What a fool believes, he sees, no wise man has the power to reason away.
Anyone else sick of these fantasies?
What ever happened to Occam's Razor?
Occam's Razor doesn't apply here. They are not trying to explain something. They are showing that something is possible. Just because negative mass is possible, doesn't mean it really exists.
Why did my brain read that headline as "Cosmetologists"?!
It was used by William of Ockham in the late middle ages to argue against the species theory of perception -- the idea that everything you can see constantly emanate images of themselves in every direction. It states (in scholastic Latin) "Do not multiply entities beyond necessity."
It was then stripped of its context somewhere halfway through the previous century, became a rallying cry of pretty much every self-proclaimed skeptic, and erroneously believed to say "the simplest explanation is usually right"
That is what happened to Ockham's razor, and I wish it had stayed in the 13th century, along with all the other idiotic arguments for and against realism about universals.
Before I read the article, I'd have been predisposed to agree with the poster who called this "The crackpot cosmology theory Du Jour". However the article does note that not only does negative matter possibly explain the current lack of detection of gravitation waves but (presumably unlike many other phenomena) predicts that if there is negative matter, we WOULD be able to detect gravitational waves but only above a certain frequency:
"the evidence that could back it up would be the discovery of the threshold frequency above which the waves do propagate"
If anyone who can read and understand the actual paper could tell us non-cosmologists when our improving technology might be able to detect gravitational waves above the cut-off frequency I would appreciate it. I mean is it technology that is (very roughly) 10 years away, 25 years, a century or basically only when we have god-like powers. I seem to remember that NASA was going to launch a space based interferometer with "arms" (free floating platforms) in a triangle 5 million km on a side. Would that be able to detect them? The whole point now isn't just to prove the existence of gravity waves but also negative matter (and the possibility of warp drives, yay!).
Actually, since (if I am reading the article correctly) they are looking for "higher frequencies", doesn't that mean the detectors should be smaller? ("arm" length shorter?) Shouldn't they be increasing the sensitivity instead? Or is the sensitivity increased by making the detector larger? I'm so confused!
Balloons have positive mass, but they float because the surrounding air has a bigger positive mass than the balloon. This can happen one of two ways. In a hot air balloon or thermal airship, the air is heated to push most of it out. Otherwise, the air is replaced with a lighter lifting gas, such as hydrogen, helium, methane, or steam.
The NASO/ESA interferometer was LISA, but NASA pulled out.
http://en.wikipedia.org/wiki/L...
As I understand it (could certainly be wrong) the whole hypothesis for "dark energy" was created to explain the reason why the Universe's rate of inflation is increasing. Also, I believe we have, so far, been unable to prove its existence except through this increasing speed of inflation.
Wouldn't negative gravity obviate the need for dark energy?
Someone on Wikipedia put together a nice image showing frequency and sensitivity of a couple different kinds of detectors and upcoming upgrades to them. There are some high frequency microwave interferometers not shown on there that could measure in the GHz range, with sensitivities to much smaller characteristic strains than on that chart. (You kind of need to multiply the strain by frequency to get something more comparable to say amplitude of EM waves, which is part of why higher frequency is more sensitive on that scale).
It's alive and well. As strange as some of the ideas are, they DO represent the most simple explanation we have for the given observations.
Consider, the whole idea of epicycles was entirely appropriate until eliptical orbist were mathematically shown to be possible and that they matched observation. Then and only then, Occam's Razor dictated that we adopt the theory that planets were in elliptical orbits.
The Doctor: "Yeah, it's fine, we're just entering conceptual space. Imagine a banana, or anything curved; actually don't, because it's not curved or like a banana. Forget the banana!"
find a way to make them in the lab. I want my anti-grav car.
The Kruger Dunning explains most post on
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.
http://www.geoffreylandis.com
That type of interferometer would be for detecting low frequency gravity waves. I think you would need some high frequency oscillating or vibrating mass in close proximity to a smaller detector in order to look for a physical threshold for the propagation of high frequency gravity waves.
Probably because negative mass addresses a hole in current physics while electric universe proposes an entire alternative system that does not match the data as well as the current 'best' model. EU proponents also generally drop down to talk about conspiracy, oppression, and heresy when questioned while the negative mass proponents go do more math.
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").
http://www.geoffreylandis.com
Dark matter conerns the "missing" (i.e. never observed directly) mass in the universe, which has despite its "invisibility" been observed indirectly; for example look up Bullet Cluster on Wikipedia.
Dark energy concerns what it is that is causing the expansion of space-time (and consequently) the universe itself.
HAND.
Ruh roh!
In C++, your friends can see your privates.
Man who doesn't understand the science, the math, or the data, calls theory crackpot. News at 11.
The Kruger Dunning explains most post on
The Electric Universe theory not only doesn't explain everything as well as our current models, but it breaks some parts and out right conflicts with others that we know to be true. It's a disproven theory with a lot of zealots spreading misinformation to make it sound like there's actually a debate.
Actually no - epicycles were an attempt to explain the motion of the planets while keeping Earth at the center of the universe, and have nothing to do with ellipses. The planetary orbits all have such low eccentricity that they are almost perfect circles anyway - IIRC as seen from Earth you never get more than a degree or so of discrepancy in planetary positions if you assume circular orbits instead of elliptical, and most planets don't vary even that much. The largest discrepancies are the result of planets changing speed in their orbits as they pass each other. It wasn't until much later, after we had a mathematical theory of of universal gravitation, that the slightly elliptical nature of the planets orbits became particularly relevant.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
You're confusing negative mass with antimatter - antimatter reacts violently with normal matter due to the nature of the quark interactions, but there's no reason to assume negative mass would do the same.
If it did though - I imagine they'd simply wink out of existence: a chunk of normal mass (antimatter included) represents mc^2 mass-energy, a chunk of negative mass presumably has the same magnitude of negative mass-energy: mc^2 + (-m)c^2 = 0.
For the rest of your post, please be aware that there are two apparently unrelated things we call mass: inertia and gravitational charge: they
are always observed in exactly the same ratio, but we haven't the faintest idea *why* that is the case. Eventually as we come to understand the nature of the Higgs field perhaps that will change.
But you are correct - whether one or the other or both properties are inverted they wreak havok on our understanding of physics, which I presume is why these folks had to treat it as a non-particle phenomena to get it to fit within our current cosmology.
My question is, if they have to treat it as a perfect fluid rather than point sources to make it work, then in what sense is it still mass rather than masses non-particle alter-ego, energy?
--- Most topics have many sides worth arguing, allow me to take one opposite you.
If negative mass and positive mass collide, what would happen? ...
I'm not positive...
Some privacy policy Slashdot.
Firstly, Dark Matter is hardly a new buzzword, it's been around for decades. And secondly, no it probably wouldn't.
Composition of the universe according to currently accepted cosmology: (from memory, the %'s are probably off a bit)
Normal matter ~= 5%
- everything we can observe directly
Dark Matter ~=20%
- Can only interact via gravity. To explain observations it must not be able to collide or clump together. Not even with other dark matter. Basically it's sort of like an invisible gas that passes right through everything.
- initially postulated to exist in order to explain the anomalous rotation curve of galaxies (like planets, outer stars were expected to orbit the galactic hub far slower than inner stars, but they don't). Relativity has recently largely explained that anomaly, but gravitational lensing anomalies continue to support it, especially around examples such as the bullet cluster (where the vast majority of the mass appears to have separated from the visible stars).
Dark Energy ~75%
- postulated to explain the fact that the expansion of the universe is accelerating, rather than slowing down as would be expected if only normal mass-energy were present. That's pretty much all we know about it, except that it appears to fill all space at the same density, and that density doesn't change as space expands, instead you just get more of the stuff at the same density. And yes - that would appear to violate conservation of energy, but that what the observations say is happening, at least within the context of our currently accepted theories of physics.
So no, negative mass is probably not a candidate for Dark Matter - dark matter has positive mass. It could possibly be a candidate for the even-stranger Dark Energy though.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
This has a couple of connotations in science (that have also existed in sci-fi previously)
The obvious one would be antigravity. What gravity attracts, it would repel. So there's your Marty McFly hoverboard. There are further connotations for other things though, such as achieving orbit or space-travel (getting too close to a gravity well at the wrong angle=not good in most cases). Depending on whether such anti-mass would be created/harvested in quantity, it could be used to cancel out mass of vehicles being sent to space, or used in propulsion.
Similarly, anti-inertia has a lot of interesting using. The old trek "inertial dampers" come to mind.
Actually yes. Copernicus discarded geocentricism and found that the heliocentric model greatly simplified things, but he retained circular orbits with the planets moving at uniform speeds which still required epicycles to match observation. (in fact, it would have required an infinite number of epicycles to exactly match observation).
Kepler took the next step with elliptical orbits and so was able to predict planetary motion with unprecedented accuracy.
Balancing would be easy I would think, just use the negative mass as your reaction mass. Example:
Float in space next to a chunk of negative inertial mass with the the same absolute mass. Push on chunk - you move away from it, and an equal-but-opposite force pushes the chunk away from you. However the chunk's negative mass means that force generates an acceleration in the opposite direction: towards you. So you and the chunk travel through space in the same direction and speed, and any time you wish to accelerate you simply push on the chunk some more, which continues to get no further away from you. Meanwhile net momentum and kinetic energy are conserved at 0 regardless of speed (though I doubt that would be much consolation to anyone you hit). Potential energy though will vary slightly depending on the strength and orientation of the local gravitational gradient.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
And you are an eloquent logician. When there is no way to experimentally verify such a theory, then it starts to shade into religious arguments. But not to worry, there will yet-another-un-testable Crackpot Cosmo "theory" next week about, I don't know, say, parallel universes. This is all elixir to all you propeller heads who want to believe that, say, warp drives can be created, but there is actual evidence that warp drive cannot be created and it is called the Fermi Paradox.
tom swift jr can finally create his repelatron!-)
Occam's razor, in the modern sense, is dead in cosmology. The most sensationalized and outlandish theories seem to be more fashionable than more mundane explanations, but what really galls me that that the acceptance of these theories happens way before the investigations have finished.
You use it to make concrete predictions about future observations. There might be several such "negative matter" theories, each with a different model and each making different predictions. Much like we had WIMPs and MACHOs for dark matter.
Then you wait for new observations that fit the predictions (or, more likely, don't), and importantly that don't fit the null hypothesis. Something new, that accepted theory doesn't explain, but some hypothesis specifically and accurately predicted.
That's the scientific method. People don't seem to get that. It doesn't require some scientist contriving the scenario being measured - it's faster when you can do it that way, but it was never required.
Socialism: a lie told by totalitarians and believed by fools.
In a way it does. They are offering that since the simplest answer was incomplete there's at least one slightly more complicated way things might work. You see, the simplest explanation isn't the thing. The simplest explanation that actually explains things is.
Anyone else sick of these fantasies? What ever happened to Occam's Razor?
Occam's Razor states that your personal theory that isn't testable is automatically false and invalid. The theory in the article that is testable may be right or wrong but we won't know until testing it.
Since your "faith" that everything you dislike must be wrong is automatically ruled out as an option, could you please stop posting useless tripe? The world would be a better place once people like you get your fingers out of science.
Dark energy for instance. Then the Type 1A supernovas at extreme distances were found to be fainter than predicted, so all of a sudden someone decided that some mysterious force was ripping the universe apart. This was immediately taken as gospel. But shouldn't more mundane, but much less fun, explanations be thoroughly exhausted first? Maybe these types of super novas were inherently less luminous 10+ billion years ago? Maybe there is some intervening material that has made them appear less luminous (I think that this has been discounted)? Maybe they are further away than we think (i.e. the redshift was different in the past).... Now Geologist/Paleontologists take this to the opposite extreme and they never seem to adopt a new theory unless dragged kicking and screaming. I'll bet there are still Ivy League rockhounds who still think the Cretaceous era was terminated by climate change. It took decades of overwhelming evidence to get most of them to change their hidebound ideas on this.
TFA grossly misrepresents the state of gravitational wave detection. Previous attempts were not expected to succeed, they were tests of the functionality of the systems.
Gravitational wave have already detected by indirect means -- their influence on celestial bodies nearby the event that produced them. We have just not yet *directly* measured gravitational waves.
Gravitational waves decrease in amplitude following the inverse square law. So the farther away an event, the smaller the wave is when it hits the earth.
The sensitivity of the detector dictates the area within which measurable events are observable. Higher sensitivity means a larger "visible area."
Measurable events occur within a given area at a given probability over time. The bigger the area, the higher the probability that an event will occur in that area within a window of time.
Detectors to date have had a visible area within which the probability of a detectable event was one in twenty five years. Observation windows have only been one to two years at a time. So the likelihood of actually making a detection has been very low, and not expected -- past "science runs" have been efforts to verify that the science and engineering works -- "dress rehearsals" so to speak. The instruments have a lot of bleeding edge science and engineering involved.
Upgrades to the detectors coming online in the next couple of years will have 10x sensitivity == 1000x large area == 1000x higher probability of a measurable event, which means likelihood of an event occurring will be on the order of one per week. It's quite likely that a successful detection will happen in the next few years.
Frequency range of the detectors depends on a variety of variables -- design limitations of the system, terrestrial noise, and models of the events that they are looking for. Any system design has given set of constraints.
Don't expect TFA to give a good understanding of that. Look at what LIGO, VIRGO, and KAGRA and doing. I'd start with this nice layperson accessible article at http://archive.ncsa.illinois.edu/Cyberia/NumRel/GravWaves.html
He's my negative mass brother!
But there probably is less than a pound of it!
They filled up the Dark X meme, so now are switching to the Negative X meme to explain oddities. We'll get Negative Matter, Negative Energy, Negative Gravity, Negative Particles (prior art?), Negative Universes, and probably Negative Feedback.
-5
Table-ized A.I.
Math doesn't take as much funding, but with enough math, you can hope to get a mite of funding.
I think we've pushed this "anyone can grow up to be president" thing too far.
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.
http://www.geoffreylandis.com
that we know to be true
... given the existing theoretical model
we must always keep in mind that, just as Newton's model turned out to be incomplete, the present model may - nay is - incomplete. Or incorrect. Or ??
It's easier to be a result of the past, but more fun to be a cause of the future! http://www.spacefinancegroup.com/
actual evidence that warp drive cannot be created and it is called the Fermi Paradox.
- that's not evidence. That's a question, for which the answer has not been determined. It's not even certain that the assertion upon which the question is based, "we have not heard from them", is true.
It's easier to be a result of the past, but more fun to be a cause of the future! http://www.spacefinancegroup.com/
Definition: "Crackpot: disagrees with me." :D
It's easier to be a result of the past, but more fun to be a cause of the future! http://www.spacefinancegroup.com/
Occam's Razor states that your personal theory that isn't testable is automatically false and invalid. The theory in the article that is testable may be right or wrong but we won't know until testing it.
Actually, no. Occam's Razor (as others have noted) is more or less about choosing the simplest theory that fits the facts. Falsifiability is about whether a theory is testable or not.
I'll just add this irrelevant point: any theory that concerns the Universe as a whole, viewed as a system from outside, is inherently unfalsifiable, even though it may be true. I can say, "the Universe is blue, viewed from outside", and there is no way to prove that, so far.
It's easier to be a result of the past, but more fun to be a cause of the future! http://www.spacefinancegroup.com/
mc^2 + (-m)c^2 = 0
OK, here I go on a wild toot. What if c^2 is negative? I.e. the "speed of light" is a complex number, or a pair of numbers, one of which is real and the other is imaginary? Then we might have c and c^2, and we can define the imaginary C=ic and C^2 = i^2c^2. This is different than the topic of negative mass, of course. I think I just boggled myself.
It's easier to be a result of the past, but more fun to be a cause of the future! http://www.spacefinancegroup.com/
They are supposed to be opposites, and let's presume they cancel each other out ...
Well, no, let's not - at least not without good reason.
Positive mass and negative mass have oppositely-signed masses. Why would that mean they'd be opposite in all other ways?
I'm no particle physicist, but negative mass seems to integrate very poorly into the system here.
Or it could just be that, not being a particle physicist, integrating negative mass into "the system" could be beyond you. It's certainly beyond me, so I'm not even going to try.
And presumably negative mass would have particles of some sort
That's an awful lot of presumptions.
systemd is Roko's Basilisk.
Wild toot is right - how exactly could a speed be negative or imaginary? It's a scalar value measuring the magnitude of the velocity vector. Even when you're doing simple physics problems and choose your reference frame for measuring such that it shows up in your equations as negative, what you're really doing is discussing one-dimensional velocity - still a vector value, and not the same thing at all.
And of course that also ignores the fact that E=mc^2 is part of a much more complicated formula providing the total relativistic energy of an object. Specifically the part which provides the rest energy of a unit of mass while neglecting all kinetic and potential energies. In that context c^2 is simply a conversion constant between rest-mass and energy - much like 12 is the conversion constant between inches and feet. If it were negative, complex, imaginary, or vectored that would radically alter the results of pretty much every particle physics experiment ever performed. As it is though particle physicists even use it as part of a common mass unit, the GeV/c^2 - a convenient unit when dealing with reactions where mass and energy are largely interchangeable.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
IIUC, it's not speculative at all. It's a work of math saying that this particular math is consistent with General Relativity. There are lots of things that are consistent with General Relativity, and most of them don't have any evidence of existing. There isn't much that appears inconsistent with General Relativity that DOES appear to exist.
Think of it as a Venn Diagram. Mark one circle "consistent with General Relativity". Mark another circle inconsistent with General Relativity. Now take a couple of
I think we've pushed this "anyone can grow up to be president" thing too far.
Balancing would be very difficult, but why bother. You just set things up so that your combined ship has a mass of 1 microgram. This means you MUST use incoming matter as your reaction mass, though...unless your proposed push-me-pull-ya drive would actually work that way. I have a hard time believing that, even though the equations WERE good enough for Dr. Forward to publish a story based around it. (He *did* assume that when negative mass contacted positive mass they both evaporated...so that's probably the right way to assume things would work out, though I wonder about electric charge, magentic fields, rotary inertia, etc.)
I think we've pushed this "anyone can grow up to be president" thing too far.
Even with pessimistic estimates for the terms of the Drake equation, the galaxy should be teeming with intelligent life, some much older than Man. If warp drive was possible, the galaxy would be single race's playground. But there is no evidence of that
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
http://www.geoffreylandis.com
There are lots of plausible reasons for the apparent lack of evidence regarding life intelligent or otherwise, which have been bandied about by many people. Just for starters, maybe we're the first intelligent life. But I wasn't arguing that point. Regardless of these questions or arguments, they are not 'evidence' about warp drive. That's all I'm saying. :)
It's easier to be a result of the past, but more fun to be a cause of the future! http://www.spacefinancegroup.com/
When can I have my flying car. The one with no wings.
Actually, at one microgram the whole thing should hold itself together quite nicely, though control might be an issue. Push on chunk and you accelerate away, meanwhile the chunk, having slightly less absolute mass, accelerates towards you slightly faster than you are accelerating away, resulting in a greater push, and even more acceleration. That could be a real problem - positive feedback is rarely a good thing unless you're trying to make a bomb. It would also seem to break conservation of energy and momentum, but I can't see any flaw in my reasoning. I think I'd go with a net mass of -1 microgram and mount weak "braking thrusters" on the chunk to add the extra little push it needs to keep up with you - then if anything failed you'd drift away and continue at constant velocity, or if mechanically connected the pull as you accelerate faster than the chunk would cause a net deceleration.
I would continue to argue against mutual annihilation though - antimatter is kind of special in that regard. Consider: generally speaking nothing in the universe actually touches - what we consider physical contact is, on an atomic level, electrostatic repulsion between electron clouds, and it keeps things far enough apart that quark interactions are extremely unlikely to occur except among the nucleons within a single atom, and between nuclei during fusion. Antimatter however has the property that anti-symmetrical particles have an opposite electrostatic charge, so electrons and anti-electrons attract each other and get within range for their component quarks and anti-quarks to annihilate. Ditto for protons and anti-protons, and they pull any (anti-)neutrons bound to them into range as well.
Negative mass could be similarly pulled together, provided that the n-m particles had at least slightly lower absolute mass, so that the repulsive forces would accelerate the n-m toward the normal mass faster than they accelerated the normal mass away. However, for annihilation to occur you'd still need some sort of mechanism for the constituent quarks to annihilate, since it is presumably not composed of anti-quarks as they have a positive mass. You might end up with some nasty inter-penetration of objects though.
Annihilation would also seem to break conservation of information, one of those laws we believe to be fundamental. Matter/antimatter annihilation preserves the information in the energy released. mass - negative mass annihilation though would presumably release no energy, the components would simply cease to exist altogether.
Hmm, perhaps this might tie back into the researchers discovery that negative mass would have to be modeled as a perfect fluid rather than point sources - that would suggest that NM can't exist as quantized particles, which might render annihilation impossible. You can't annihilate only a fraction of a quark without fundamentally breaking Quantum Mechanics. If it also lacked electric and color charges it might behave in many ways similar to how dark Dark Matter is believed to operate (though presumably with opposite gravitational effect) - passing through normal matter continuously without visible effect except at scales large enough for diffuse gravitational sources to become apparent. Possibly a Dark Energy candidate?
As an added bonus, presuming that NM can only interact with normal matter gravitationally would also eliminate those nasty conservation-breaking effects of our space drive, though sadly it would do so by rendering the entire thing impossible in the first place. Bye-bye convenient chunk of contained negative mass.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
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.
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Fascinating. Thanks for answering.
Existing physics models are incomplete and incorrect. However, to introduce a new one, you need to show that it explains some things better than the current theories, and at least isn't inconsistent with all the other things. Special relativity explained things like the Michelson-Morley experiment and the orbit of Mercury, and wasn't inconsistent with all the other things because it could be shown that its predictions were essentially Newtonian for most of what we observe.
Usually, what "we know to be true" involves actual observations, not just theoretical predictions. A new model can't get away with brushing away conflicts between observation and predictions.
Not to mention that what you say in the above post is thoroughly characteristic of the crackpot. There's nothing novel about saying that current models are incorrect and incomplete, because everybody knows that already, and only crackpots don't seem to realize that.
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
Just for clarity, I have no idea what the "Electric Universe" is, and not much curiosity to find out. As for the last bit, it was just a reminder to the parent that "what we know to be true" ain't necessarily so.
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OK, didn't mean to pick on you unjustly. However, what we know to be true is in very close agreement with what we observe in very many areas. If somebody wants to change that, they have to provide good explanations as to how their theory explains things pretty much as well as current theories, and at the very least a way to distinguish the theories using experiment and observation. I'm not a physicist, but I saw people blast string theory as being untestable.
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
Scientific ideas do rise and fall based on their merits. In the case of really disruptive ideas (e.g., Special Relativity), it can take a generation. Fortunately, those come along infrequently enough that we can afford to delay.
And the fact is that at least ninety-nine percent of the ideas out there that look like crackpot notions are indeed crackpot notions.
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes