Dark Matter Is an Illusion, New Antigravity Theory Says • Hacker News Board

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#11

Post by fractallyte » Sun, Sep 04, 2011, 6:46 AM UTC

mberning wrote: post #10

I remember being completely blown away in undergraduate physics classes by how much of the world can be exactly and precisely explained by various subject areas of physics (kinematics, gas laws, thermodynamics, etc.) Then at some point I ran in to a wall with quantum mechanics and particle physics where I had to throw up my hands. I was contemplating going to graduate school for a masters in physics but I decided aga…

!?

Within these 'disparities' lie new understanding, and awesome discoveries that will change the world. Just as quantum mechanics did at the beginning of the 20th Century...

The resolution of these disparities is part of the thrill of Science!

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#12

Post by Confusion » Sun, Sep 04, 2011, 8:57 AM UTC

foob wrote: post #8

colanderman wrote: post #6

Earlier quoted context omitted.

Why wouldn't we see this effect on earth, and have taken it into account when determining the strength of earth's own gravity? Would we see this effect with electric fields as well? Could differently oriented electric and gravitational fields compete to orient a given dipole?

You've ask a couple of very deep questions there. Why wouldn't we see this effect on earth, and have taken it into account when determining the strength of earth's own gravity? We could be observing the impact of this without exactly realizing it. I won't speculate too much on this because I haven't read enough about it but it might make more sense in light of my next answer. Would we see this effect with electric fi…

The whole 'virtual photons' thing is a physical interpretation of the mathematics, but it is a mistake to conclude that this is how it 'actually' is. There is a mathematical model that works. I don't think we know how it 'actually' is. There is every reason to doubt that this sea of 'virtual photons' has any physical reality in an independently verifiable way. Occam's razor doesn't favor solutions that involve multitudes of invisible, unmeasurable, particles popping in and out of existence.

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#13

Post by fhars » Sun, Sep 04, 2011, 10:47 AM UTC

127 wrote: post #9

foob wrote: post #8

Earlier quoted context omitted.

You've ask a couple of very deep questions there. Why wouldn't we see this effect on earth, and have taken it into account when determining the strength of earth's own gravity? We could be observing the impact of this without exactly realizing it. I won't speculate too much on this because I haven't read enough about it but it might make more sense in light of my next answer. Would we see this effect with electric fi…

One thing I don't understand: wasn't there just discovered a ring of antimatter circling around the Earth? Wouldn't it just disperse into space if antimatter caused antigravity? Stupid question, I know, but just something that's beyond my comprehension.

No, those are charged particles interacting with the magnetic field of the earth. Gravity is such a ridiculously weak force that you can safely ignore it in situations like that.

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#14

Post by hga » Sun, Sep 04, 2011, 11:25 AM UTC

jbri wrote: post #4

This theory is basically that gravity is similar to other forces in that it's not solely attractive, but things of opposite "gravitational charge" (i.e. particles and antiparticles) repel. If that holds, then an ambient gravitational field in an area would presumably be strengthened by virtual particle pairs aligning their gravitational dipole with that of the ambient field, quite neatly explaining the anomalous obse…

That was E.E. "Doc" Smith's assumption in the Lensman series when "negaspheres" were developed (planetary scale antimatter objects), in Grey Lensman written circa 1939. They had an "opposite 'gravitational charge'", a tractor beam would repel them while a pressor beam would pull them in, etc. It would be amusing if this turned out to be true (well, ignoring the yet to be if ever invented beam technology).

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#15

Post by hollerith » Sun, Sep 04, 2011, 12:37 PM UTC

127 wrote: post #9

foob wrote: post #8

Earlier quoted context omitted.

You've ask a couple of very deep questions there. Why wouldn't we see this effect on earth, and have taken it into account when determining the strength of earth's own gravity? We could be observing the impact of this without exactly realizing it. I won't speculate too much on this because I haven't read enough about it but it might make more sense in light of my next answer. Would we see this effect with electric fi…

One thing I don't understand: wasn't there just discovered a ring of antimatter circling around the Earth? Wouldn't it just disperse into space if antimatter caused antigravity? Stupid question, I know, but just something that's beyond my comprehension.

Tiny amounts of antimatter were just discovered circling around Earth. The anti-grav effect on the antimatter particles is swamped by the effects of the Earth's gravity and magnetic field.

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#16

Post by colanderman » Sun, Sep 04, 2011, 1:21 PM UTC

foob wrote: post #8

colanderman wrote: post #6

Earlier quoted context omitted.

Why wouldn't we see this effect on earth, and have taken it into account when determining the strength of earth's own gravity? Would we see this effect with electric fields as well? Could differently oriented electric and gravitational fields compete to orient a given dipole?

You've ask a couple of very deep questions there. Why wouldn't we see this effect on earth, and have taken it into account when determining the strength of earth's own gravity? We could be observing the impact of this without exactly realizing it. I won't speculate too much on this because I haven't read enough about it but it might make more sense in light of my next answer. Would we see this effect with electric fi…

Thanks for the answers, they were helpful. Especially the Renormalization link looks exciting.

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#17

Post by dedward » Sun, Sep 04, 2011, 1:32 PM UTC

Confusion wrote: post #12

foob wrote: post #8

Earlier quoted context omitted.

You've ask a couple of very deep questions there. Why wouldn't we see this effect on earth, and have taken it into account when determining the strength of earth's own gravity? We could be observing the impact of this without exactly realizing it. I won't speculate too much on this because I haven't read enough about it but it might make more sense in light of my next answer. Would we see this effect with electric fi…

The whole 'virtual photons' thing is a physical interpretation of the mathematics, but it is a mistake to conclude that this is how it 'actually' is. There is a mathematical model that works. I don't think we know how it 'actually' is. There is every reason to doubt that this sea of 'virtual photons' has any physical reality in an independently verifiable way. Occam's razor doesn't favor solutions that involve multit…

In the end, all we have are our mental models and experiments to back them up.... we'll never know what anything 'actually' is - all we can do is model things to whatever degree of accuracy we can.

A construction worker doesn't need to go around thinking about his hammer as being made up of mostly empty space, and of the electromagnetic forces that give it it's properties, it's a hammer! We all know what it "IS" right?

But it's not that. It's not even what we think it is. It's not even what the best physicists think it is.... and in the end, all we're left with are incomplete mathematical models, or models that are only accurate on a certain scale.

BTW - how do we then explain hawking radiation, if virtual particles are "just math" and not real?

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#18

Post by Steuard » Sun, Sep 04, 2011, 1:59 PM UTC

I find it ironic that this article features a picture of data on the Bullet cluster, which is currently one of the strongest pieces of evidence favoring dark matter as a form of matter. Hajdukovic is quoted as saying that he's "currently expanding his theory to account for these observations." That translates as "I haven't found a compelling way of explaining them yet."

It's great that he's considering alternatives to the usual approach, and it would be fantastic to have a second viable model to test observations against: competing theories encourage open-mindedness. I'm really happy to have his work up on the arXiv. But I don't believe that a speculative idea like this merits attention in the mainstream press until it can at least give plausible explanations for the major successes of existing models.

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#19

Post by philwelch » Sun, Sep 04, 2011, 2:10 PM UTC

This seems plausible to me. I'm not a physicist, but I think the case of dark matter can be compared to the case of the planet Vulcan.

In the early 20th century, in the heyday of discovering planets by observing existing planets and realizing that classical mechanics didn't quite predict their orbits correctly, it was observed that Mercury's orbit didn't fit the classical model well enough. Reasonably enough, it was presumed that there was another planet orbiting inside of Mercury's orbit. This planet was dubbed "Vulcan", and the fact that no one had ever observed Vulcan was explained away by the fact that it was clearly too close to the sun to be observed. This was all well and good until the early heyday of Einstein's theories, which made small but crucial changes to the mathematical models of classical mechanics. The orbit of Mercury was found to be perfectly consistent with Einstein's model.

The question of dark matter supposes a dichotomy: either our current understanding of physics is essentially accurate and there's a ton of fundamentally unobservable matter in the universe that explains any anomalous observations, or our model of physics isn't quite right yet. Intuitively, I think it's more likely our physics are off.

Re: Dark Matter Is an Illusion, New Antigravity Theory Says

#20

Post by splat » Sun, Sep 04, 2011, 4:08 PM UTC

philwelch wrote: post #19

This seems plausible to me. I'm not a physicist, but I think the case of dark matter can be compared to the case of the planet Vulcan. In the early 20th century, in the heyday of discovering planets by observing existing planets and realizing that classical mechanics didn't quite predict their orbits correctly, it was observed that Mercury's orbit didn't fit the classical model well enough. Reasonably enough, it was…

Either way our model of physics is off. Currently, the most reasonable explanation for dark matter is that it consists of some unknown, weakly-interacting particle. However, the standard model of physics predicts the existance of no such particle. Even this, the most mundane possibility, requires radical changes to our most fundamental physical theories.