Gravity is incredibly weak. Just think about it: you can lift your foot off the ground, despite the entire mass of the Earth that grabs it. Why is she so weak? Unknown. And it might take a very, very large scientific experiment to find out. James Beecham is a Duke University physicist who works with the ATLAS detector at the famous Large Hadron Collider in Switzerland. He recently described his physics experiment for Gizmodo: an incredibly large atomic accelerator - the Ultra-Hadron Collider - located at the outer edge of the solar system.
Such an experiment could solve most of the mysteries of physics right away, for example, reveal the true nature of dark matter or prove the possibility of time travel.
Thought experiment: a solar system-sized collider
Physicists are confident they know the basic principles of the universe. Particles interact through forces, of which four are known: electromagnetism; "Weak" strength; "Strong" strength; gravity. Each force has rules that we have found through experiments over hundreds of years. Some fundamental interactions are stronger, some are weaker.
Compared to the other three, "gravity isn't just weak, it's practically insignificant," Beecham says. Further - from the first person.
At the Large Hadron Collider, where I worked, we study the basic, elementary rules of nature by pushing protons together at high energies. The rules we're investigating are described in particle and force terminology, and gravity is the only one of the four known forces that we don't even pay attention to when calculating the highest energy collisions of protons. If we endow a strong interaction with a force of 1, gravity will have a force of 10-39. 39 zeros after the decimal point. That is, nothing at all.
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This mystery of science is one of the most incomprehensible to us. Why are the forces of interaction lined up in this way? Why is gravity so weak?
Nature is what it is, no matter how people imagine it. But experiments have shown that at high enough energies, electromagnetism and weak force merge together into one force. At even higher energies, scientists believe, strong interactions will also join them. But gravity is different. Scientists don't know if gravity will combine with the rest of the forces at high enough energies.
"Gravity is a force of nature, but its rules - the mathematics that underlie it, the most accurate description - are somehow very different from the rest," says Beecham. And he continues:
Gravity is best described by Einstein's general theory of relativity, and the other three forces that are described by the Standard Model of particle physics are based on quantum field theory. And although there are similarities, they are different. That is, when we naively try to sew them together, we get meaningless answers.
In our present universe, using our current technology, “it's almost impossible to find an empirical answer to this question,” Beecham says. Why? "We cannot get to such high collision energies, primarily because we cannot build a collider big enough to do this." He says that some theorists believe there is something else (like other particles or extra spatial dimensions, as suggested by string theory and its extended models) that might appear in an experiment that combines gravity with other forces.
But for that we need a solar system-sized collider.
Even the 27-kilometer circular Large Hadron Collider, which uses superconducting magnets to accelerate and collide proton beams at 99.999999% of the speed of light, is not fast enough to answer these questions. He can only find out what the universe was like when it was the size of an apple. Scientists may need more energy and therefore a larger collider to make sense of a universe smaller than an apple.
How much more? Perhaps strong and weak nuclear forces could be combined with a collider built around Mars. But to add gravity to this equation, “according to some rough estimates, a collider would be required to encircle Neptune's orbit. Moreover, some scientists argue that this estimate is very rough and we will have to build a bigger ring. The benefits would be enormous - such a collider would be able to test the Planck scales, the smallest scales we can look into that quantum mechanics allows. “We would understand everything about gravity, about quantum mechanics and, meanwhile, would also get a combined electroweak and electrostrong force just like that, followed by time travel, string theory, dark matter, dark energy, the problem of measurement, the theory of multiple universes etc.
What? Time travel? According to Beecham, we would get such a detailed understanding of the universe and how space-time works that we could possibly put our knowledge into the basis of future technologies for manipulating time.
"It is possible that the force of gravity and other forces of nature combine at some extremely high energies, but to investigate this issue we will need to create a collider like the LHC, encircling the outer reaches of the solar system or even more."
Unfortunately, Beecham's thought experiment is not feasible at this time:
“The technology, human strength and resources to create a particle collider that encircles the outer reaches of the solar system simply does not exist. Even if we took the technologies of the existing accelerator and detector at the LHC, the scale would be a problem in the most practical sense: it is not clear whether there is enough material to create this colossus in the solar system, at all sources - the Earth, the Moon, planets, asteroids, etc. …
And to accelerate protons to such high energies, even at the LHC, we use superconducting magnets. Magnets become superconductors only if you make them very cold. One would think that this would be useful for creating a particle accelerator in space. The cosmos is very cold. But for superconductivity, it's not very cold. Outer space has a temperature of 2.7 Kelvin, but magnets require 1.9 Kelvin. Close, but still not. At the LHC, these temperatures are achieved using liquid helium. It is unclear if there is enough liquid helium anywhere nearby to cool a circular accelerator the size of the solar system.
At these energies, the detectors must be huge. You will have to train physicists and acquire an incomprehensible amount of computing power. You will need advanced robotics, protection from asteroids, comets and other debris. And all this still needs to be set in motion. You cannot use the energy of the Sun, because the machine surrounds the Sun at a distance of Neptune. A device of this size will require energy breakthroughs that are not feasible in the near future.
Such an experiment would change physics. After all, such experiments help physicists understand how things work, and such an accelerator will provide convincing answers to many questions. It will change the way people think. Will change what we mean by "understanding."
If we were building a collider around the outer boundary of the solar system, the knowledge that we would acquire is about the nature of gravity, about how to combine quantum mechanics and general relativity into one, about time travel, about what happened at the time of the Big Bang, about whether our Universe can be just one of an infinite number of multiple universes - would change our idea of reality, our attitude to nature, this language of it, understanding of the world, humanity in general, our place in the universe so much that we had to would invent a new concept of understanding to describe it.
Obviously, no one is working on such an experiment, although CERN is already developing on paper the Future Circular Collider, the tunnel of which will be 80-100 kilometers long. However, perhaps somewhere in the Universe is working on such a project.
It would be fantastic if some distant civilization somewhere else in the Universe was already working on this, and we had at least the opportunity to find and contact her to ask about the results of even ordinary physical experiments. Do they have the same mass of the Higgs boson? Did they find X and Y bosons that demonstrate the unification of electroweak and electrostrong forces? Did they get to the Planck scale? What is dark matter? Can we move back in time?
The universe will continue to operate according to the same laws. The real question is whether humans will ever be able to understand these laws.
Ilya Khel
