What if we could cancel the force of gravity and fly upwards without effort? Or stand in midair among the clouds using anti-gravity technology? That would be quite awesome indeed! However, at the same time, it seems a pretty wild idea… Is there any hope something like this will ever be possible? Perhaps, it depends on how we define things like anti-gravity and gravitational cancellation.
Anti-gravity as cancellation mechanism
We can think of canceling gravity on Earth by means of a reversed gravitational effect, literally an anti-gravitational force that repels instead of attracts. However, the options for such an opposing force are quite limited.
The current best theory of gravity, Einstein’s General Relativity[1][2], does actually allow for such an anti-gravity effect. However, it requires negative mass. Negative mass??? Yes, and it’s as exotic as it sounds. In fact, scientists sometimes even refer to it as an example of “exotic matter”[3].
An anti-gravity force by using negative mass to cancel gravity
By using somewhat of an oversimplification, we can say that negative mass involves something weighing less than 0 kg. According to the established physical laws something weighing, let’s say -1 kg, would result in a (very tiny) repulsive gravitational force.[4][5] We could call this repulsive force an anti-gravity force.
However, the problem is that material with negative mass is simply not available, because no one has ever found it. Therefore, the possibility to cancel gravity using negative mass remains purely theoretical. It’s not impossible that scientists will ever discover something like it, but don’t hold your breath!
Apart from the fact that negative mass is not available, there are other reasons why it’s not a solution for canceling gravity. Let’s assume we have some negative mass on Earth. It would repel (positive mass) objects to some extent. However, the negative mass would be very tiny comparing to the total mass of the Earth. Hence, it wouldn’t neutralize the Earth’s gravity in any meaningful way. Only if we’d replace a very significant amount of the Earth’s mass by negative mass, you’d notice an actual effect that one might call gravitational cancellation or anti-gravity.
Negative mass chasing positive mass
And even if such a replacement were possible, very weird things would start to happen. Current theories assume that when we’d combine an equal amount of positive and negative mass, the negative mass will chase the positive mass![6][7] That’s because the positive mass will move away from the negative mass and the negative mass will move towards the positive mass. It may not be wise though, to try that with our dear planet Earth! Fortunately we don’t have to worry about that, as it seems utterly impossible to replace half the Earth with negative mass.
So, it seems that on Earth we can forget about any practical form of gravitational cancellation (anti-gravity) by using negative mass. What else can we consider for canceling gravity?
Antimatter probably does not result in anti-gravity
While negative mass is elusive and controversial (as discussed above), antimatter is an accepted phenomenon in physics. Antimatter particles are very similar to their normal matter counterparts, with the important difference that their charges are reversed. The most obvious example of such a charge is the electric charge, which is indeed reversed for antimatter particles. For example, an electron has negative electric charge while its antiparticle (the positron) has a positive electric charges. It seems not a huge leap to explore the possibility that gravity might also be reversed for antimatter. And, some researchers indeed anticipated that antimatter would behave differently gravitationally than normal matter. [8][9] Some suggested repulsive (reversed) gravity in relation to antimatter, and even argued that it might be an alternative for concepts such as dark energy and/or dark matter.[10][11]
However, so far it doesn’t look like antimatter comes with some form of anti-gravity. A recent experiment appears to confirm that antimatter comes with regular gravity rather than anti-gravity.[12][13] And while the debate goes on, it doesn’t currently look like antimatter is going to be the silver bullet in humanity’s efforts to cancel gravity.
Canceling gravity through blocking, shielding, or otherwise interfering with it
Another approach that has sometimes been suggested is canceling gravity by blocking, shielding, or otherwise interfering with it.[14] Unfortunately, though, this approach also doesn’t look very promising. Gravity is not a force in the same way that for example electromagnetism is a force. That might sound a bit vague so let’s clarify:
- Electromagnetism is a force for which there is a known particle that carries the force, the photon. For example, (virtual) photons travel through the electricity wire connected to the lamp that lights up your home. If you break the flow, let’s say by cutting the wire, your lamp won’t work anymore.
- Also, and perhaps an easier way to look at it, let’s consider what happens when your lamp is on but you close your eyes. By closing your eyes, you effectively block photons from hitting your eyes’ retinas. This means that you are successfully shielding your eyes from the source of the photons (your lamp).
So, electromagnetism is what’s behind electricity as well as light. And in both cases it’s possible to interfere with the electromagnetic force as briefly explained above.
Please note that the short explanation above focuses only on photons, and is for illustrative purposes in the context of this article only. It leaves out key aspects, and is obviously not a substitute for a proper explanation of electromagnetism. We’ll gladly leave that to the many books that exist on this topic.[15][16][17]
A gravity shield to cancel gravity, is that possible?
When it comes to gravity, according to General Relativity, there is no particle that carries the gravitational force. Instead, what we perceive as the gravitational force is the result of a geometrical effect. It concerns the warping (curving) of space due to the presence of a large mass/energy (such as the Earth or the Sun).[18]
In this view, there is no particle that we can block, shield, or interfere with. Therefore, it should not be possible to block gravity, apply gravity shielding or otherwise interfere with the gravitational effect. Unfortunately that applies also to, let’s say, the gravitational effect of our Earth on an object that we try to launch into space. And thus, blocking gravity by using a gravity shield sounds awesome, but according to General Relativity it is not a viable way to cancel gravity.
PS: We are not going into quantum theories of gravity here. A quantum theory of gravity would involve some kind of quantization of the gravitational field and thus a particle (often called a graviton) that carries the gravitational force. A large number of physicists around the world are working on such theories. However, currently there is no accepted quantum theory of gravity.
Canceling gravitational waves
How about gravitational waves? It seems a small step to assume that gravitational waves can cancel in the same way as sound waves can cancel. More precisely, it seems natural to think that gravitational waves can neutralize each other via destructive interference. In fact, scientists believe it’s indeed possible for interference effects to occur in gravitational waves.[19][20] However, this effect is totally irrelevant for the purpose of finding an anti-gravity solution!
We also discuss gravitational waves in our article about gravitational amplification. As mentioned there, gravitational waves have nothing to do with our every day experience of gravity. For example, if we consider a rocket ship launching from Earth into space, gravitational waves are totally irrelevant for any practical purposes. The simple reason for this is that gravitational waves have absolutely nothing to do with the Earth’s gravitational pull on objects on its surface or around it. The Earth’s presence causes the space around Earth to warp (curve). This warping results in what we perceive as the Earth’s gravitational pull. This doesn’t involve gravitational waves…
So, even if cancellation of gravitational waves is technically possible to some extent, this is not going to help us to create an anti-gravity technology as alluded to in this article.
Failed or unproven anti-gravity ideas
The above notwithstanding, several anti-gravity mechanisms have been suggested by various scientists and other people over the years. Obviously, none of them are working so far otherwise the world would look a lot different than it does today. Surely, though, some descriptions of anti-gravity theories and anti-gravity machines can be found[21][22][23]. And some even suggest that it is possible to create anti-gravity drives or to make anti-gravity propulsion systems work.[24]
These ideas are based on various mechanisms. Some are completely different from the negative mass and gravity shielding / gravity blocking “mechanisms” mentioned above. Without going into detail on all these different ideas, we’ll simply recognize that so far none of them actually work. They don’t cancel gravity in any practical sense. And in cases where a researcher claimed to have found an anti-gravity effect, other scientists have not been able to reproduce such effects in experiments.
Canceling gravity in science fiction
There are plenty of sci-fi series, movies and books that introduced various anti-gravity devices that block gravity or otherwise cancel the effects of gravity. Star Trek is an obvious example where anti-gravity technology is readily available.[25] Science fiction also frequently uses the concept of material that shields against the force of gravity[26] (we briefly discussed gravity shielding in the section above). With a gravity shield in hand (perhaps even literally), gravitational cancellation is not an issue in sci-fi it seems!
Anti-gravity technology and avoiding “how does it work?”
Science fiction writers sometimes take the privilege to use a gravity shield, or other anti-gravity machines in their stories, without explaining how the devices actually work. This is a convenient way for the stories’ heroes to benefit from anti-gravity technology while avoiding the need to come up with a plausible explanation of the mechanism that cancels gravity. That way, an anti-gravity aircraft/plane or anti-gravity enabled spacecraft is not a problem in sci-fi. Scientists, engineers, or others trying to invent or build real-world solutions, obviously don’t have this luxury!
Anti-gravity products
Marketers and other creative minds also happily use the term anti-gravity, and similar terms. Consequently, we have products such as:
- The Anti-Gravity Treadmill™
- Anti-gravity cakes
- Anti-gravity yoga
- Zero gravity chairs
- Anti-gravity batteries
- Anti-gravity phone cases
- And even… an anti-gravity goat[27]
Some of the above are actually good for your health, but we suggest going easy on the cake:) Obviously, none of these have anything to do with actual anti-gravitational effects and they don’t actually cancel gravity. Although, perhaps it depends on how we look at it. Let’s consider this further in the next section.
Canceling gravity by countering it with another force
Is it possible to “cancel” gravity by simply working against it with another force? Now, that’s a lot more down to Earth! Anyone who has ever been on an airplane, or simply jumped in the air, can confirm that it’s possible. Does that mean it’s easy? That depends on how far we want to push it.
If we want to go up into space, we need an awful lot of force to counter the gravitational pull of the Earth. Hence, the huge rockets used to launch stuff into space. The price per kilogram (kg) for launching something into space is a good proxy measure for how easy or difficult it is. If it were easy, it would be cheap, right? Following such cost calculation logic, we can conclude that it’s not so easy at all! In fact, the cost per kg of payload to be launched into “low Earth orbit” is still measured in thousands of US Dollars.[28][29] Launch vehicles created by private companies, such as SpaceX, bring down the average cost per kg but it remains very expensive even today.
Apart from it not being easy, can we actually call this gravitational cancellation? That’s a fair question because in the rocket launch example above we are of course not really canceling gravity in the sense that was alluded to earlier in this article. And, it’s certainly not anti-gravity. In fact, when launching a rocket, we are simply working against gravity to eventually overcome it. Hence, in this case, “overcoming gravity” is probably more appropriate.
Let’s get creative with anti-gravity and gravitational cancellation
As this article probably made very clear, an actual mechanism that cancels gravity is not easy to come by. However, that won’t stop us from giving it a go:). For the sake of coming up with creative and potentially useful ideas, we’ll temporarily let go of some restrictions imposed on us by existing theories and laws of physics. What ideas related to anti-gravity or gravitational cancellation can we come up with? Is there a once-in-a-generation idea out there that will change the world?
Great article!!!
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