I personally believe that there are anti-gravity. But many doesn't. Any idea?

Firstly, gan, can you explain:

(1) what you mean by anti-gravity.

According to the opinion expressed in Wikipedia:

"Anti-gravity is the idea of creating a place or object that is free from the force of gravity. It does not refer to the lack of weight under gravity experienced in free fall or orbit, nor to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift."

(2) why you believe it.

I believe because I believe that all field have its anti field. Like gluon field has an anti-gluon field. Anti-quarks field, anti-electromagnetic field and so on. I just believe.

[quote=redewenur]
"Anti-gravity is the idea of creating a place or object that is free from the force of gravity. It does not refer to the lack of weight under gravity experienced in free fall or orbit, nor to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift."
[quote]
I think that any force that opposes the gravitational integration of matter can be regarded as anti- gravity force. Electromagnetic repulsion can also be regarded as anti-gravity. The energy possessed by a body acts against gravitational integration, and so that also can be regarded as anti-gravity force; however, it is just a pseudo force in the sense that it represents the force equivalent of the energy.

Have you heard of anything that you think is observational evidence for your belief?

finiter

You can define it however you want to, so long as we are clear for the purpose of communicating the ideas.

When R. Feynman was asked about a possible anti-gravity device, he replied that the pillow the guy was sitting on was a good example!

It's actually quite difficult to define an anti-gravity device that is not an every-day object, like the chairs we might be sitting on, or a familiar force like the electromagnetic force.

Perhaps what is really implied is some way of "turning off" gravity so that an object, in a gravitational field, can free-float when everything around it is firmly attached to the ground.

Gan, if that's what you have in mind I suspect you will have to be very young if you are to have any hope of living to see that. I could be wrong, of course; it has happened before.

Yes, Bill, what gan has in mind is a repulsive field, sort of anti-Higgs I suppose. Years ago I would have dismissed it out of hand, but times have changed. With Dark Energy on the scene and the quantum world spookiness, I have a much more open mind. Let's hope my brains don't fall out.

If they do, and you have any left over when you put them back, remember - I asked first!!!

"Provided as is. Use at your own risk"

How soon we forget , dont you remember the floating frog?
sure it cost 50,000,000 to float the frog but they did float it.

http://www.youtube.com/watch?v=2VlWonYfN3A

they claim the reason the frog floats is because its magnetic but I dont see any part of the frog pointing in any particular direction.

and if the magnetic frog is in a magnetic field the frog would snap to a certain position then stop.

just like a magnet would.

Pull the other one! It's a frog in a washing machine.

LOL okay I will add a weirder one in and this has been a serious discussion in the lab yesterday.

After a long friday evening drinks a group of us played around with accoustic levitation (http://science.howstuffworks.com/acoustic-levitation.htm).

Only we decided to invert it and put piezo emitters on a platform and fire the above audio sound at the floor to levitate the platform. What we found was to lift 12.5 gram the sound wave intensity cracked floor tiles which only a well placed file cabinet is currently hiding and we sort of had to abandon the project.

Yesterday there was an article released (http://www.physorg.com/news/2011-08-bragg-x-rays-limit.html)

So now your question what energy of x-rays is required to levitate 1Kg over a floor surface made of the perfect diamond material in the report.

Hint: E = MC2 so M = E/C2 now convert to x-ray particle energies ;-)

Mind you I bags not being anywhere near the test !!!!!

Accoustic levitation; that's old hat!
See "Peanuts" in which Lucy has been using that technique for decades. And that's without a long evening drinking.