I wonder what’s so wrong with anti-gravity? All I know is that the laws of physics lack a theoretical means of clarifying its mechanism (or lack) of exist, I have never heard of how the laws of physic specifically forbid it from existing. I was wondering if any physicist or students of physics could explain this to me (a meager biochemistry student)

So is anti-gravity and/or gravity control forbidden or not?
This is question came to me from this thread:
http://www.sciforums.com/showthread.php?s=&postid=471487#post471487

If u mean a force that can be generated which is repulsive and depends on two objects masses then NO. If u brought a large enough object (say a planetesimal) close to earth then the ATTRACTIVE force of that body would cancel out the ATTRACTIVE force of the earth and we would ferel no gravity in between. Gravity is however, always attractive.

not as attractive as some girls I know tho! :)

But is there anything that forbids the existance of anti-gravity?

Originally posted by Neuromancer
I wonder what’s so wrong with anti-gravity? ::snips:: I have never heard of how the laws of physic specifically forbid it ::snip:: So is anti-gravity and/or gravity control forbidden or not?


I'll answer this with a question, so you can see where I am coming from. Is an anti-agathic expressly forbidden in biochemistry. Is there any reason why cells should not die?

The point is that Anti-Gravity is not forbidden, per se, but it has also never been directly oberserved. Without an observation to build models we really can not begin to describe it either.

What we can say is that Gravity is caused by mass so anti-gravity is caused by anti-mass, or negative energy. If we have no idea what it is we can't really control it.

I also appreciate the full story is a lot more complex but I'm trying to keep this simple.

I don't believe in negative time, energy or space.

Originally posted by John Connellan
I don't believe in negative time, energy or space.

Belief is not good enough in science. Can you proove it?

Look up the effects of the symmetry of the FRW models, to whit, an Einstein-Podolsky-Rosen bridge plus the Dirac Equation and what it says about anti-matter. As I say, the story is more complex. Factor in Dark Energy and Inflation and you may say that we do have a clue about anti-gravity. A very small clue though.

How does physics describe "dark energy?" You know, the repulsive
gravity that is supposedly making the universe expand at an
ever increasing rate?
edit: Sorry, thed, I didn't see your post before submitting mine.

Originally posted by 2inquisitive
How does physics describe "dark energy?" You know, the repulsive
gravity that is supposedly making the universe expand at an
ever increasing rate?

Unfortunately I am not up on the current models for Dark Energy. Lethe perhaps? Or James R?

thed

Actually no anti-agathic is not expressly forbidden in fact there are many organism that live unusually long for their metabolisms and some forms of bacteria do not undergo senescence even though they have been alive for millions for years! If you count reproduction many organisms never die (just divided). Though the idea of immortality in general is consider impossible because physics tell us the universe will either run out of energy or crunch in on it self eventually.

A better analogy would be to ask if life can break the laws of thermodynamics, which it can’t nor is there any detection or understanding in biochemistry of a enzyme that can catalyze a reaction that is thermodynamically nonspontaneous without energy input.

I want to here a answer like "Anti-gravity is forbidden because it breaks _________ law(s) by doing _____________"

Originally posted by Neuromancer
thed

Actually no anti-agathic is not expressly forbidden

I'm trying to think of a good answer here and failing. But I'll try anyway.

In the same way we can not conceive of a pharmaceutical drug that grants immortality we can not conceive of a method of gravity control. Both are hypothetically possible, if we really understand all the factors, but current understanding says no.

In my opinion, if either was possible then we should see them. We have not yet ergo they are likely impossible. This is not to say they are not impossible.

I want to here a answer like "Anti-gravity is forbidden because it breaks _________ law(s) by doing _____________"

Wish I could. My feeling (it's a feeling, not a proof so take this as given) is that we are far off such a statement.

one can show, mathematically, that a spin two field can only be attractive between two masses. if you believe einstein, then you are forced to conclude that there is no antigravity. all particles follow geodesics.

dark energy is not a repulsion between masses, it is the addition of this cosmological constant, which accelerates the universes expansion. you can give it an equation of state, wherein it will have a pressure, but it will never be repelled from anything. it can t be, it is just the vacuum!

Both are hypothetically possible

That all I wanted to know, so anti-gravity does not violate any laws its just it is not confirmed to exist by any reasonable theory either.

In the same way we can not conceive of a pharmaceutical drug that grants immortality we can not conceive of a method of gravity control. Both are hypothetically possible, if we really understand all the factors, but current understanding says no.

ya that makes sense. thanks. :)

Originally posted by Neuromancer
That all I wanted to know, so anti-gravity does not violate any laws its just it is not confirmed to exist by any reasonable theory either.


i do not agree... antigravity violates the equivalence principle.

Originally posted by lethe
i do not agree... antigravity violates the equivalence principle.

Could you explain that?, I would like to know.

Originally posted by Neuromancer
Could you explain that?, I would like to know.

the equivalence principle states that gravitation is equivalent to freefall along a geodesic. the geodesic is determined by the metric, which is a spin 2 tensor field, which, as i said above, can only beget an attractive force.

thus, gravitational repulsion is inconsistent with the equivalence principle.

Neuromancer,

I just wanted to share an extremely hypothetical possibility. If we assume that a gravitational field has a sister field, just like the electric field has a magnetic field, then it would be possible to create an artificial anti-gravity field by rotating a mass at high speed (complex rotation).

It may also be possible that particles that travel at the speed of light, like photons, have a dipolar gravitational field which would permit them to accelerate to c in gravitational fields.

Finally, it might also be possible that some of the new particles created in particle accelerators have anti-gravity fields, but there are no sensors in the accelerators set up to measure anti-gravity.

>>>....If we assume that a gravitational field has a sister field, just like the electric field has a magnetic field, then it would be possible to create an artificial anti-gravity field by rotating a mass at high speed (complex rotation).....<<<

This equivalent is called a gravitomagnetic field and frame dragging is such an effect ( if it actually exists- Gravity Probe B will look for this). If the mass is spinning, it should distort the usual field representative of static mass.

This is my opinion only- In response to the question posed, re. is anti-gravity forbidden.
Do you mean a repulsive force or cancellation of attraction?
I do not think that either is forbidden and if the universe is actually accelerating in its expansion, it would seem that a repulsive force is also possible.

beta,

This equivalent is called a gravitomagnetic field and frame dragging is such an effect ( if it actually exists- Gravity Probe B will look for this). If the mass is spinning, it should distort the usual field representative of static mass.

I just looked up "gravitomagnetic" at google.com and found it everywhere on the net. Gee, I thought it was my idea. :( It turns out that it is predicted by GR.

About a year ago when I suggested on sciforums that the precession of a gyroscope is the result of the gravitomagnetic field being converted into a dipolar gravitational field, I was laughed at. I have now found a website implying the same thing:

http://www.colorado.edu/physics/phys7840/phys7840_fa02/precess/precess.html

It appears that if the gravitomagnetic field really does exist, then it may be possible to build an antigravity propulsion engine.

well well its old prosoothus

:)

spookz,

well well its old prosoothus

Did everyone miss me?? :D

Originally posted by Prosoothus
spookz,



Did everyone miss me?? :D

you know we did!

http://www.theologyweb.com/forum/images/smilies/offtopic.gif

>>It appears that if the gravitomagnetic field really does exist, then it may be possible to build an antigravity propulsion engine

There is little doubt of its existence. It is very much the relativistic equivalent of the magnetic field for a charge in motion, but occurs when mass has a speed component. However, it is not actually a magnetic field.

>>About a year ago when I suggested on sciforums that the precession of a gyroscope is the result of the gravitomagnetic field being converted into a dipolar gravitational field, I was laughed at...

Yes, frame dragging is expected to effect the precession of a number of gyroscopes on Gravity Probe B.
If you derived this without prior knowledge of this effect, you're done well :)
Sorry to dampen your enthusiasm- It always seems that whatever we are capable of thinking of, someone has already done so.

Originally posted by Prosoothus
spookz,
Did everyone miss me?? :D

give em hell!