Could Anti-Gravity Ever Be Possible?

[christoff01]

Hello to everyone.
I feel quite humble to be posting on this physics forum as I am not a physicist but I am in awe of such great minds. However, I do have a general interest in physics as I am an engineer. Unlike my father is an electronics design engineer for whom is the reason for my posting this.

I need some proffesional insight into why Anti-Gravity is impossible as my father seems to have worked out how to overcome gravity using one way inertia. Is it Isaac Newtons third law that prevents this? I have been reading and researching a lot on the internet and it seems that the third law may have some flaw. Please help as I am confused.

 

[chroot]

No one can really honestly say that anti-gravity isn't possible; we don't have a complete theory of the universe yet. On the other hand, there is a preponderance of evidence -- every experiment ever conducted -- as well as quite a number of theoretical arguments against anti-gravity. It seems quite likely that anti-gravity does not exist, but it would not be scientifically valid to assert that it must not exist.

It is possible that a sort of "negative mass" exists, and such a negative mass would exhibit repulsive, rather than attractive, gravitation. While you can make all kinds of wild conclusions from theory, it happens that no trace of any such stuff has ever been detected.

As it happens, I must say that your father is probably just quite mistaken. There is no way to defeat gravity without creating a sort of matter that doesn't seem to exist in this universe. There's certainly no way to find a flaw in Newton's laws that might permit anti-gravity. Newton's third law is very commonly misapplied because it's easy to accidentally forget to include a force where there should be one. If you start including rotation or other complications, most people with little experience will begin making mistakes. In fact, I'd venture that fully 75% of anti-gravity kook theories on the 'net involve a simple misapplication of basic mechanics.

If your father can build a device that demonstrates anti-gravity, have him do so -- he'll be the richest and most well-known man on the planet. If he cannot, there's no choice but to chalk up whatever mechanism he "worked out" as a mistake.

- Warren

 

[russ_watters]

My take on anti-gravity is that the devices said to operate on it are operating on some mis-interpreted other force like the forces due to the gyroscopic effect or magnetism. Sure, you can levitate an object with magnets that are working oposite the force of gravity, but that's not anti-gravity.

 

[MiGUi]

That's it. We don't understand yet how gravity works. We can't explain why you can't hide from gravity as you can be isolated from an electromagnetic field.

The fact is that gravity and electromagnetism are very similar. Field theory works well with it, but we can't make an object with mass to repel another mass.

 

[Mentat]

My take on anti-gravity is that the devices said to operate on it are operating on some mis-interpreted other force like the forces due to the gyroscopic effect or magnetism. Sure, you can levitate an object with magnets that are working oposite the force of gravity, but that's not anti-gravity.

This is an excellent point, russ. It's easy to see how such mistakes could occur given the common definition of gravity: "The force of attraction between two objects". Electromagnetism is a "force of attraction between two objects" too, as is the strong nuclear force. So, working under that definition, any mechanism that creates repulsion instead of attraction could be considered an "anti-gravity device".

I have a friend who's working on anti-gravity, and he's re-defined gravity (in his hypothesis) as simply "altered inertia"...but that doesn't really help much, IMHO. After all, electromagnetism would (once again) fall into that same definition.

I think it's best to stick with Relativity's definition of gravity as (basically) a bending of spacetime by the presence of positive mass, and thus (as chroot said) we would need an object with "negative mass" (which is a theoretical mess, and has never been found in experiment) to create "anti-gravity".