4 ms·

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. particl

by jbri 15y ago

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 observations that brought about the dark matter theory in the first place. There are more recent observations that this new theory doesn't yet explain, but it doesn't seem an insurmountable challenge. Additionally, this theory makes one very testable hypothesis - that antimatter is oppositely-charged, gravitationally, to normal matter. If that's not the case, we should be able to determine that fairly soon (a few years, perhaps).

colanderman 15y ago
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?
- foob 15y ago
  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 fields as well? We absolutely see this effect with electric fields. In the last century we've grown to understand that in electromagnetism we don't simply deal with isolated electrons and positrons. These particles are actually surrounded with clouds of virtual electrons and photons which have an impact on the field (this is a simplified view but it's enough along the right lines to give you the right impression if you haven't studied physics). When we talk about the field around an electron we take this into account by assuming that all these contributions sum to give us the field that we actually observe. If you want to read more about this then http://en.wikipedia.org/wiki/Quantum_field_theory#Renormalization http://en.wikipedia.org/wiki/Quantum_field_theory#Renormaliz... is a good starting point. Could differently oriented electric and gravitational fields compete to orient a given dipole? Yes, all relevant fields will have an impact on what's happening. I don't want to speculate too much beyond my knowledge though and when it comes to quantum gravity we're already there. I know that this wasn't the deepest contribution but hopefully it will help shed some light to someone...
  - 127 15y ago
    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.
    - fhars 15y ago
      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.
    - hollerith 15y ago
      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.
      - mparr4 15y ago
        According to this theory, it would be the magnetic field alone--not the gravitational field--that is overwhelming the antigravity effect. After all, if these particles had an opposite "gravitational charge", then their experience of gravity wouldn't be attractive but would be equal in magnitude but opposite in orientation. Hence "anti"gravity.
        hollerith 15y ago
        I accept the correction. Good one.
  - Confusion 15y ago
    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.
hga 15y ago
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).

by jbri 15y ago

colanderman 15y ago

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?

foob 15y ago
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 fields as well? We absolutely see this effect with electric fields. In the last century we've grown to understand that in electromagnetism we don't simply deal with isolated electrons and positrons. These particles are actually surrounded with clouds of virtual electrons and photons which have an impact on the field (this is a simplified view but it's enough along the right lines to give you the right impression if you haven't studied physics). When we talk about the field around an electron we take this into account by assuming that all these contributions sum to give us the field that we actually observe. If you want to read more about this then http://en.wikipedia.org/wiki/Quantum_field_theory#Renormalization http://en.wikipedia.org/wiki/Quantum_field_theory#Renormaliz... is a good starting point. Could differently oriented electric and gravitational fields compete to orient a given dipole? Yes, all relevant fields will have an impact on what's happening. I don't want to speculate too much beyond my knowledge though and when it comes to quantum gravity we're already there. I know that this wasn't the deepest contribution but hopefully it will help shed some light to someone...
- 127 15y ago
  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.
  - fhars 15y ago
    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.
  - hollerith 15y ago
    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.
    - mparr4 15y ago
      According to this theory, it would be the magnetic field alone--not the gravitational field--that is overwhelming the antigravity effect. After all, if these particles had an opposite "gravitational charge", then their experience of gravity wouldn't be attractive but would be equal in magnitude but opposite in orientation. Hence "anti"gravity.
      - hollerith 15y ago
        I accept the correction. Good one.
- Confusion 15y ago
  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.

hga 15y ago

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).