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Cosmologists Show Negative Mass Could Exist In Our Universe

Unknown Lamer posted about 2 months ago | from the beam-me-up dept.

Science 214

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.

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"Absence of observations" (1)

i kan reed (749298) | about 2 months ago | (#47474557)

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?

We've observed and created antiparticles (2, Informative)

Anonymous Coward | about 2 months ago | (#47474579)

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).

Re:We've observed and created antiparticles (1)

i kan reed (749298) | about 2 months ago | (#47474621)

Not only have we created them, we have small stores at CERN and a few other facilities for experimentation on.

Re:We've observed and created antiparticles (1)

Anonymous Coward | about 2 months ago | (#47474725)

Not only have we created them, we have small stores at CERN and a few other facilities for experimentation on.

True, and one of the stated goals at CERN is to try and measure the gravitational pull of antimatter has the same sign as that of matter, but trying to get that information out at the single-atom level is not easy due to the relatively large electric charge they have compared to their tiny (positive or negative) mass.

Negative mass- not antimatter, but odd (5, Informative)

Geoffrey.landis (926948) | about 2 months ago | (#47474705)

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 [nasa.gov] 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... [aiaa.org]

Re:Negative mass- not antimatter, but odd (1)

gstoddart (321705) | about 2 months ago | (#47475037)

So, I will happily demonstrate my complete lack of understanding on this topic ...

Is this similar to, unrelated to, part of, dissimilar, orthogonal, integral, or in any way linked to Dark Matter?

Because I (and probably most of us) don't understand that either.

Re:Negative mass- not antimatter, but odd (5, Funny)

ColdWetDog (752185) | about 2 months ago | (#47475187)

Almost, but not quite, entirely unlike Dark Matter.

Re:Negative mass- not antimatter, but odd (1)

gstoddart (321705) | about 2 months ago | (#47475357)

LOL, so you don't know either then?

Re:Negative mass- not antimatter, but odd (3, Funny)

ColdWetDog (752185) | about 2 months ago | (#47476405)

Hell, I don't even know what we're talking about.

Dark energy is negative (2)

Geoffrey.landis (926948) | about 2 months ago | (#47475381)

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.

Re:Dark energy is negative (1)

gstoddart (321705) | about 2 months ago | (#47475457)

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)

Wait ... dark matter and dark energy are separate things now? Are they related? Or totally separate things?

Honestly, are you guys just fucking with us? ;-)

You're in good company! If you did understand it, you could publish, and you should be getting a phone call from Stockholm soon.

Oh, good, I'm not supposed to understand it.

OK, it's official, cosmologists are just fucking with us. It's the post-modernism of the sciences where nobody actually knows what you're talking about. Gotcha. ;-)

Yes, they're separate (3, Informative)

warrax_666 (144623) | about 2 months ago | (#47475571)

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.

Re:Dark energy is negative (4, Informative)

Bengie (1121981) | about 2 months ago | (#47475607)

Dark Matter and Dark Energy are two completely unrelated issues. Dark Matter is the unaccounted mass that is leading candidate as to why the rotational speed of galaxies is not matching observed matter and is definitely creating gravitational lensing in empty space. Dark Energy is the unexplained force driving galaxies apart, even faster than light in some cases. This is related to the expansion of space.

Re:Dark energy is negative (1)

Immerman (2627577) | about 2 months ago | (#47476245)

I thought the anomalous galactic rotational curve had been almost entirely explained a year or two ago by repeating the analysis using the far more computationally expensive Relativity theory rather than the known-flawed Newtonian theory of gravity. There's still the gravitational lensing anomalies, bullet cluster, etc. supporting the existence of DM, but the while galactic rotation was the impetus for postulating it's existence, it's no longer a strong supporting argument.

Re:Dark energy is negative (0)

Anonymous Coward | about 2 months ago | (#47476615)

For the last ten years or so there have been calculations and proposals that GR explains the rotation curves, but there have also been a lot of criticism and questions about those calculations. Part of this has to do with the GR calculations using simplified models, treating mass distrubution as some simplified dust distribution function that makes the calculations easier. Some of the counter arguments complain that the density model is unphysical and contains features too far from reality even if it is a close fit elsewhere (e.g. infinite density within the galactic plane, even if it has finite mass). Some other complains include things like misunderstanding what would actually be the measured rotation velocity, instead confusing a term with frame dragging with velocity, which is kind of damning in that one case.

The result is it is kind of a quagmire at the moment, and are still those with calculations that claim to suggest GR doesn't change anything significant.

Re:Dark energy is negative (0)

Anonymous Coward | about 2 months ago | (#47476175)

Dark matter and dark energy were ALWAYS separate things. Although, they are both placeholders so things we don't understand, yet.

Re:Negative mass- not antimatter, but odd (1)

cuby (832037) | about 2 months ago | (#47475093)

I don't know very little about the subject, but I have a question and a speculation.
The question is what would happen in an encounter of 2 objects with symmetrical masses?
The speculation is about negative mass and antimatter... What if, somehow, negative mass was more attracted to antimatter? Could that explain why there is so little antimatter around?

Re:Negative mass- not antimatter, but odd (1)

GameboyRMH (1153867) | about 2 months ago | (#47475117)

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.

Aw dammit, I was hoping we could build antigravity vehicles from this stuff...or at least some negative mass body panels to lighten up my car :-(

Re:Negative mass- not antimatter, but odd (0)

Anonymous Coward | about 2 months ago | (#47475293)

Eh, that's no problem matey.
We just use negative antimatter!

Re:Negative mass- not antimatter, but odd (0)

Anonymous Coward | about 2 months ago | (#47475167)

My conclusion is that negative gravitational mass can't imply negative inertial mass, as you've assumed. Using F = k.m1.m2/r^2, then a = F/m1 = k.m2/r^2 (i.e. assuming inertial mass goes negative too) we find that for ++, things are mutually attracted, for --, things are mutually repelled, but for +- we have that the - mass is attracted but the +mass is repelled, in complete violation of Newton's 1st law. If the two things had the same mass value and started at rest, the - mass would chase the + mass forever, and gain infinite energy in doing so. That's a dealbreaker. So negative gravitational mass can't imply negative inertial mass. If inertial mass is always positive, even for negative gravitational mass, then for ++ and -- there is mutual attraction and for +- there is mutual repulsion, which is in agreement with Newton's 1st law and doesn't have this bad solution.

Re:Negative mass- not antimatter, but odd (1)

jeffb (2.718) (1189693) | about 2 months ago | (#47475239)

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.

Trying my best to ignore my intuition, which is heavily biased toward "all mass is positive":

A negative mass would fall down in a gravitational field (generated by a positive mass) -- it would experience a force directed away from the positive mass, and it would respond to that force by moving toward the positive mass.

However, the negative mass would repel the positive mass gravitationally -- effectively, exert a force directed away from itself -- correct?

It seems to me that if you had two equal but opposite masses in freefall, the negative mass would accelerate toward the positive, the positive would accelerate away from the negative, and the negative mass would chase the positive mass off the edge of the universe at constant acceleration.

It also seems like two negative masses would repel each other (exert a force directed away from each other), but respond to that repulsion by accelerating toward each other.

What am I missing?

Negative mass is weird (5, Informative)

Geoffrey.landis (926948) | about 2 months ago | (#47475525)

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").

Re:Negative mass is weird (1)

jeffb (2.718) (1189693) | about 2 months ago | (#47475641)

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. But it can't move forward, because presumably negative and positive matter can't simply interpenetrate -- or can they?

Gaah, so many microscopic/macroscopic behavior assumption violations...

Re:Negative mass- not antimatter, but odd (1)

geekoid (135745) | about 2 months ago | (#47475679)

You should do an ama.

Re:Negative mass- not antimatter, but odd (1)

Immerman (2627577) | about 2 months ago | (#47476285)

>Negative mass reacts oppositely to both gravity and intertia.

Well, that's one hypothesis. But as I recall there are several hypothesis for each of the three possible interpretations of "negative mass", and none of them have any supporting evidence for actually existing.

Re:Negative mass- not antimatter, but odd (0)

Anonymous Coward | about 2 months ago | (#47476727)

Negative mass reacts oppositely to both gravity and intertia.

Isn't this an assumption based on the fact that so far inertial and gravitational masses are the same? If things are going to get weird and speculative about forms of things never before seen, there doesn't seem to be any guarantee that that equivalence holds.

Re:Negative mass- not antimatter, but odd (1)

Anonymous Coward | about 2 months ago | (#47477017)

I'll write -apple to indicate a negative mass apple and +apple for the conventional fruit.

Within a limited area (limited enough that tidal effects can be ignored) there’s supposed to be no way to tell whether you’re held to the floor by a gravitational field or by the room accelerating upwards. Imagine a box floating freely in space. An +apple and an –apple float side-by-side within the box. If rockets propel the box upwards, both apples stay where they are. A observer within the box sees both hit the floor. On the other hand, place the box on the surface of the Earth. If the +apple falls down and the –apple falls up, Relativity goes out the window. The only way to avoid this paradox is for gravity to repel the –apple but, having negative inertia, it reacts to the repulsion by dropping to the floor.

Weird, huh?

So, if –apples behave the same way as +apples, what’s the difference? Are we just splitting hairs?

No. An –apple would have a negative gravitational field. “Normal” matter would move away from it.

We place an +apple and an –apple side-by-side in space. The –apple "falls" towards the +apple. The +apple "falls" away from the –apple. So the pair begin to move and they accelerate forever!! Since they have a net mass of zero, their kinetic energy and momentum remain zero. No conservation laws are violated.
The late Dr. Robert Forward wrote several technical papers and an entire SF novel about this.

On the other hand, if the +apple runs into a brick wall at several km/sec, it’s going to make a fair-sized hole. Where did the energy to break the bricks come from? You don’t expect the wall to reform as the –apple deals it a second blow, do you?

Negative mass would be useful -- but I remain skeptical.

Re:We've observed and created antiparticles (0)

seven of five (578993) | about 2 months ago | (#47474717)

Sorry! Antimatter has positive mass. Now go look for stuff with negative mass. Thanks!

Re:We've observed and created antiparticles (1)

Dcnjoe60 (682885) | about 2 months ago | (#47475313)

But an anti-hydrogen atom still has mass.

Re:We've observed and created antiparticles (1)

hAckz0r (989977) | about 2 months ago | (#47475707)

No, I think the next step is likely that someone will 'mathematically prove' that you can have anti-energy or something cruft like that, to explain away Dark Energy. Where the word 'prove' actually means 'infer' from some magical fantasy land mathematical contortions. Once you divest yourself from the physical reality you can twist equations around to do many impossible things. Why so many people invent fantasy to try and explain away actual evidence is beyond me. At least with anti-matter we have actual evidence of it. We can create it, and experiment with it. Its physical.

You just can't do that with Dark Matter or Gravity waves, because they simply don't exist. General Relativity is thermodynamically incomplete as a theory and no amount of fantasy-like invention is going to compensate for an incorrect/incomplete theory.

Re:We've observed and created antiparticles (0)

Anonymous Coward | about 2 months ago | (#47476759)

Why so many people invent fantasy to try and explain away actual evidence is beyond me

Because it is one of the steps of the scientific method? When current theories are good enough, or even when they are but one is being skeptical, you create new theories to see if things can be explained better, then use those theories to make predictions.

Re:"Absence of observations" (0)

Anonymous Coward | about 2 months ago | (#47474609)

We have directly observed and even created antimatter, we have not observed negative mass.

Re:"Absence of observations" (1)

i kan reed (749298) | about 2 months ago | (#47474631)

Yes, but the point was that we don't really see much sign of it in the stars above, not that we've never observed it at all.

Re:"Absence of observations" (0)

Anonymous Coward | about 2 months ago | (#47474677)

Observations of antimatter in space has been made quite a few times now, from the positron and antiproton component of cosmic rays (although a rather small minority) to mapping of 511 keV gamma rays that show locations of a few diffuse clouds of it outside our galaxy and involvement in high energy reactions from pair production. Negative mass would be closer to the opposite than similar, because we have no observations of it on Earth, and at best say it is not inconsistent with observation of the cosmos.

Re:"Absence of observations" (1)

i kan reed (749298) | about 2 months ago | (#47475183)

Come on man, I said "much". I'm aware of the history here.

Re:"Absence of observations" (0)

Anonymous Coward | about 2 months ago | (#47474793)

But that's not entirely correct. We have detected antimatter in small quantities in nature usually as a byproduct of high energy collisions with cosmic rays.

Though technically I think we managed to manufacture it before we managed to spot it in nature.

Re:"Absence of observations" (1)

cheesybagel (670288) | about 2 months ago | (#47474629)

Of course it does exist. It was discovered by Dr. Cavor and is sold as Cavorite(TM).

Re:"Absence of observations" (1)

NotDrWho (3543773) | about 2 months ago | (#47474981)

The summary makes mention that we haven't noted any substantial signs of this material

They're just pointing out that it CAN exist, like unicorns and the Loch Ness monster.

Re:"Absence of observations" (0)

Anonymous Coward | about 2 months ago | (#47476561)

It's funny because we're using something we can't see to explain why we haven't seen something else we can't see.

Re:"Absence of observations" (1)

i kan reed (749298) | about 2 months ago | (#47477031)

It's not about sight. It's always about measurement.

The crackpot cosmology "theory" Du Jour (0, Troll)

Squidlips (1206004) | about 2 months ago | (#47474601)

Anyone else sick of these fantasies? What ever happened to Occam's Razor?

Re:The crackpot cosmology "theory" Du Jour (4, Interesting)

Kokuyo (549451) | about 2 months ago | (#47474649)

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.

Forget the banana! (1)

bigpat (158134) | about 2 months ago | (#47475191)

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!"

Re:The crackpot cosmology "theory" Du Jour (4, Insightful)

dpilot (134227) | about 2 months ago | (#47474655)

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.

Re:The crackpot cosmology "theory" Du Jour (0)

Anonymous Coward | about 2 months ago | (#47475371)

Re: "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."

But, notice that negative mass is a legitimate topic on Slashdot, while the Electric Universe is not, even though what the EU theorists propose is to apply the laboratory plasma models to the cosmic plasmas. This is apparently heresy, while negative mass is not. The problem is these idealized models. They should all be viewed with skepticism until some sort of experimental support emerges.

I'm getting the sense that the way in which we teach science -- mainly through the exemplars (aka problem sets) -- is crippling peoples' ability to intelligently question the models. Everybody is looking for a technical solution, as if humans did not build these theories. Human-built theories will surely exhibit human-oriented biases, but you'd never know it from reading Slashdot.

Re:The crackpot cosmology "theory" Du Jour (1)

jythie (914043) | about 2 months ago | (#47475503)

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.

Re:The crackpot cosmology (0)

Anonymous Coward | about 2 months ago | (#47475689)

while the negative mass proponents go do more math

If only they could do some experiments...

Re:The crackpot cosmology "theory" Du Jour (0)

Anonymous Coward | about 2 months ago | (#47475815)

The problem is these idealized models. They should all be viewed with skepticism until some sort of experimental support emerges.

Except that this idea is not even at the point of being something that could be viewed with skepticism and experimental evidence, it is as most currently a curiosity, something that is merely considered possible now. Saying something might be possible given current data and analysis is a long ways from saying it looks like it is out there which is a long ways from saying it is an integral part of our model of the universe.

even though what the EU theorists propose is to apply the laboratory plasma models to the cosmic plasmas

This is also what plasma physicists and astrophysicists do constantly too... yet they come to different conclusions while EU theorists act like astrophysicists ignore plasma.

Re:The crackpot cosmology "theory" Du Jour (1)

Bengie (1121981) | about 2 months ago | (#47475837)

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.

Re:The crackpot cosmology "theory" Du Jour (0)

Anonymous Coward | about 2 months ago | (#47474707)

I'm not sure how it is a fantasy to say something that was thought to be inconsistent with observations can be made not inconsistent. That is not saying it is out there, only we can't rule it out. Occam's Razor still applies unless we come up with observations that can only be explained by negative mass but not otherwise without inventing a whole different mess of stuff.

Occam and White (2)

Geoffrey.landis (926948) | about 2 months ago | (#47474727)

What ever happened to Occam's Razor?

It competes with the totalitarian principle, "everything that is not forbidden is compulsory."

Re:The crackpot cosmology "theory" Du Jour (1)

Roger W Moore (538166) | about 2 months ago | (#47474799)

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.

Re:The crackpot cosmology "theory" Du Jour (1)

bunratty (545641) | about 2 months ago | (#47474803)

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.

Re:The crackpot cosmology "theory" Du Jour (0)

Squidlips (1206004) | about 2 months ago | (#47476119)

It is mere speculation unless it is testable. How do you test this theory?

Re:The crackpot cosmology "theory" Du Jour (0)

Anonymous Coward | about 2 months ago | (#47476709)

This is mostly speculative, and not being pushed as some grand solution. That said, it does have some testable implications, such as a briefly mention of absorbing gravity waves. If further improvements to high frequency gravity wave detectors finally get some results while lower frequency ones do not, this would match the implications.

Re:The crackpot cosmology "theory" Du Jour (1)

Charliemopps (1157495) | about 2 months ago | (#47474821)

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.

Re:The crackpot cosmology "theory" Du Jour (0)

Anonymous Coward | about 2 months ago | (#47474853)

You're a fucking idiot. These "crackpot" theories have as much chance or more of being valid as you do of being educated in cosmology.

Re:The crackpot cosmology "theory" Du Jour (0)

Anonymous Coward | about 2 months ago | (#47475517)

Lol!!!

What happened to Occam's razor. (2)

kruach aum (1934852) | about 2 months ago | (#47474869)

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.

Re:What happened to Occam's razor. (1)

kruach aum (1934852) | about 2 months ago | (#47474891)

Excuse me, 14th century.

Re:The crackpot cosmology "theory" Du Jour (1)

sjames (1099) | about 2 months ago | (#47475159)

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.

Re:The crackpot cosmology "theory" Du Jour (1)

Immerman (2627577) | about 2 months ago | (#47476439)

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.

Re:The crackpot cosmology "theory" Du Jour (2)

geekoid (135745) | about 2 months ago | (#47475701)

Man who doesn't understand the science, the math, or the data, calls theory crackpot. News at 11.

Yeah, it's called ANTI-MATTER (-1)

Anonymous Coward | about 2 months ago | (#47474627)

Dumshitz! Known sinze the mid sixtiez.

Re:Yeah, it's called ANTI-MATTER (1)

NEDHead (1651195) | about 2 months ago | (#47474643)

wrong

Re:Yeah, it's called ANTI-MATTER (1)

seven of five (578993) | about 2 months ago | (#47474731)

"Not even wrong."

Well, duh, balloons! (-1)

Anonymous Coward | about 2 months ago | (#47474663)

Of course there is negative mass. What do you think makes balloons float? Magic pixie fairies?

Re:Well, duh, balloons! (0)

Anonymous Coward | about 2 months ago | (#47474843)

It's Sylphs not Pixies.

F'ing balloons, how do they float? (1)

tepples (727027) | about 2 months ago | (#47474899)

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.

Re:F'ing balloons, how do they float? (0)

Anonymous Coward | about 2 months ago | (#47474939)

So, yeah, magic pixie fairies have a higher mass so they lift up the balloon.

Re:F'ing balloons, how do they float? (0)

Anonymous Coward | about 2 months ago | (#47474983)

WHOOOOOSH

Re:F'ing balloons, how do they float? (1)

tepples (727027) | about 2 months ago | (#47475011)

What is the sound of one balloon inflating?

Oh wait, I forgot, this isn't Jeopardy!.

Finally... (1)

Richard_at_work (517087) | about 2 months ago | (#47474709)

A goal for all those zero sized models and weight loss fanatics to aim for!

This kind of thing confuses me (1)

Tx (96709) | about 2 months ago | (#47474733)

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?

Re:This kind of thing confuses me (1)

Joe Gillian (3683399) | about 2 months ago | (#47474777)

You forgot the most important question:

Can I use this to make a flying car and/or hoverboard?

Re:This kind of thing confuses me (1)

mikael (484) | about 2 months ago | (#47476461)

Given that negative mass atoms repel each other, a negative mass planet would never form. Even if one did form, it would disintegrate rather violently within seconds. Probably be fun too watch.

So, negative mass atoms could only form thin gas clouds.

Re:This kind of thing confuses me (4, Interesting)

Immerman (2627577) | about 2 months ago | (#47476657)

An excellent question, and as yet we don't have an answer.

There are actually two apparently unrelated phenomena we call mass - inertia and "gravitational charge", and last I heard we don't even have any substantial hypotheses as to why the two always seem to appear in the same ratio. The properties of a "negative mass object" would vary wildly depending on whether one or the other, or both properties were negative.

Negative gravitational mass only would mean you have an object that behaves as normal, but would presumably be repelled from normal gravitational matter (and then there's the question of how it would react to other negative matter - a naive hypothesis would be mutual attraction - rather like electrostatics except that like charges attract and dislike charges repel.

Negative inertial mass would likely mean that acceleration would be in the opposite direction of applied forces - push on a chunk and it would move towards you (basis for a cool "reactionless" drive?). This would also be repelled from normal mass, but for a different reason - gravitational forces would pull on it just like normal matter, but the resulting acceleration would be in the opposite direction.

If both are negative then you get stuff that acts like normal matter so long as only gravity is affecting it - gravitational forces would repel it from normal matter, but since the inertial mass is negative the resultant acceleration would be toward the gravitational source. All other forces would still result in backwards acceleration.

Why do we keep trying, then? (1)

bittmann (118697) | about 2 months ago | (#47474787)

Having built a number of gravitational wave observatories that have to see a single gravitational wave...

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?

;-)

Re:Why do we keep trying, then? (0)

Anonymous Coward | about 2 months ago | (#47474949)

Yeah, like the ones your mom makes.

Damn my dyslexic brain! (1, Funny)

Wayne Osteen (3575995) | about 2 months ago | (#47474859)

Why did my brain read that headline as "Cosmetologists"?!

Re:Damn my dyslexic brain! (-1, Offtopic)

Anonymous Coward | about 2 months ago | (#47475257)

Because you're a moron with a Facebook login, and therefore presumed to have no idea of what is being discussed here?

Re:Damn my dyslexic brain! (-1)

Anonymous Coward | about 2 months ago | (#47476769)

Mod parent up. GP is a faggot.

OMG! A (possibly) testable theory! (5, Interesting)

wisebabo (638845) | about 2 months ago | (#47474877)

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!

Re:OMG! A (possibly) testable theory! (1)

steamraven (2428480) | about 2 months ago | (#47475017)

The NASO/ESA interferometer was LISA, but NASA pulled out.

http://en.wikipedia.org/wiki/L... [wikipedia.org]

Re:OMG! A (possibly) testable theory! (1)

bigpat (158134) | about 2 months ago | (#47475407)

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.

Re:OMG! A (possibly) testable theory! (2, Informative)

Anonymous Coward | about 2 months ago | (#47475133)

Someone on Wikipedia put together a nice image [wikipedia.org] 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).

Ok, but the thing is ... (0)

TrollstonButterbeans (2914995) | about 2 months ago | (#47475073)

If negative mass and positive mass collide, what would happen?

They are supposed to be opposites, and let's presume they cancel each other out ...

What could they cancel out into? You still have to conserve the energy.

High energy photons can create particles with mass if they strike matter, what kind of photons would the negative mass particles be related to?

Even positive and negative mass don't cancel out, would having a lot of positive mass and negative mass in the same area cancel out gravity?

What role does the Higgs play in negative mass?

I'm no particle physicist, but negative mass seems to integrate very poorly into the system here.

And presumably negative mass would have particles of some sort, some sort of unusual electrons or quarks or protons or maybe none of those --- but all mass as we know it interact with photons (neutrinos excluded?), so presumably negative mass would need to reflect light or absorb it.

Re:Ok, but the thing is ... (1)

Immerman (2627577) | about 2 months ago | (#47476799)

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?

Re:Ok, but the thing is ... (1)

bledri (1283728) | about 2 months ago | (#47476845)

If negative mass and positive mass collide, what would happen? ...

I'm not positive...

Dark energy (1)

MikeMo (521697) | about 2 months ago | (#47475079)

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?

Re:Dark energy (1)

geekoid (135745) | about 2 months ago | (#47475819)

The 'dark' in 'Dark energy', means we don't know what it is.
It wouldn't obviate the need for dark energy, it would be dark energy.

COme on (1)

geekoid (135745) | about 2 months ago | (#47475325)

find a way to make them in the lab. I want my anti-grav car.

I feel dumb (0)

Anonymous Coward | about 2 months ago | (#47475347)

I feel dumb for posting this but could this also be another explanation for the new science buzz word "dark matter"?

Re:I feel dumb (1)

Immerman (2627577) | about 2 months ago | (#47476995)

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.

have to see? (0)

Anonymous Coward | about 2 months ago | (#47475411)

have yet to see?

I'm seriously asking....I assume thats the typo?

Round a way round? (1)

scuzzlebutt (517123) | about 2 months ago | (#47475653)

Ruh roh!

Uhhh What? (0)

Anonymous Coward | about 2 months ago | (#47475737)

Why would a bunch of people doing makeup care about the mass in the Universe?

It has long been suspected (0)

Anonymous Coward | about 2 months ago | (#47475749)

that the President's brain is made from negative mass.

Useful as a space-drive all by itself (0)

Anonymous Coward | about 2 months ago | (#47475903)

As mentioned above by Geoffrey.landis, negative mass matter has a number of very interesting properties.

Among them are that if you were to balance a matter spaceship with an equal (negative) mass of anti-mass
matter, then it takes essentially no energy to accelerate the combined craft to very high speeds.

Balancing them, however, might be a problem. If you apply a force to an anti-mass, it accelerates the 'wrong'
direction.

It's not at all clear that a mixture of mass and anti-mass would not be self-separating.

This is repulsive (0)

Anonymous Coward | about 2 months ago | (#47476125)

Negative mass?! That would have a gravitationally REPULSIVE effect, and nothing seems to be repeling on a large scale!

Oh wait......

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