After fifteen years of relentless experiments, new work has once again shown the immense strength of general relativity.
In science, theories are built and undone at a sometimes dizzying speed. Even the strongest of them are only a shattering counter-example. But there are still some concepts that work so well that they have become almost irremovable; this is the case with general relativity conceptualized by Albert Einstein himself. The latter has even just successfully passed the milestone of a critical experiment conducted by Australian researchers which could have called the whole concept into question.
To understand the progress of this work spotted by Space.com, we must first take an interest in the objects on which they are based: the pulsars. These are celestial bodies in rotation which constantly emit violent radiation, which reaches us in the form of pulsation, hence their name. But the real important point is that they are much more massive than our Sun, whose size is hundreds of thousands of kilometers. Beside the pulsars are only a few kilometers in diameter but have an equivalent mass, or even greater. It is this absolutely phenomenal density that gives them very interesting properties.
This makes them, of course, fascinating objects for astronomers, who have tracked them since their discovery in 1968. In the early 2000s, they spotted a couple located about 2400 light years from our Earth. Both had the particularity of being located on either side of the same center of gravity, around which they orbit at more than a million km / h.
A tango between cosmic heavyweights
For physicists of all stripes, there was therefore something to be excited about; the tango of these two heavyweights is indeed the ideal laboratory to study them in detail for more than fifteen years. “Such rapid orbital motions of such compact objects allow us to test many predictions of general relativity that we could not otherwise experiment with.”Enthuses Fick Manchester, astronomer at the Australian Space Agency (CSIRO).
Fortunately, these observations have kept all their promises. At the end of all these years of effort, the researchers have achieved a real hit, since the various points they sought to confirm have all been validated, one after the other. The pulsars behaved exactly as Einstein’s work predicted, down to the smallest detail. The authors were notably able to observe the effects of the famous temporal dilation which occurs in intense gravitational fields, as is the case near these pulsars. “Our precision has allowed us to measure the effects of time dilation which slows down clocks in gravitational fields.”, Explains Manchester.
In the world of astronomical research, researchers have been trying to find fault with general relativity for over a century, but they have never succeeded so far. Despite the blows of science, the more than century-old theory continues, for the moment, to be infallible. It is not this new work that will come to affirm the contrary. The theory of general relativity is therefore seen today as one of the pillars of our scientific knowledge, in the same way as the laws of gravity or Maxwell’s equations, which, in a completely different field, have allowed major advances. .
Towards the famous Theory of Everything?
But the adventure does not end there for researchers in fundamental physics, far from it. Because every time work reminds us of the solidity of general relativity, we inevitably see the specter of the famous “Theory of Everything“.
This theory was Einstein’s ultimate goal, and a whole section of theoretical physics is still trying to achieve it. In essence, it would be a question of finding a unique and comprehensive theory which would bridge the yawning gap that exists between general relativity and quantum physics, formalized in what is called the Standard Model of particle physics. These two theories describe extremely well the phenomena that we observe in our world, and form the basis of much of our science.
But the concern is that they may work extremely well, at present, they remain irreconcilable. “General relativity is great for explaining how things work on a very large scale, but it doesn’t work at all at the scale of atoms anymore.”Recalls Adam Deller, another astrophysicist affiliated with the study. “At this level, quantum physics takes over”, He adds. And then we find ourselves in a new dead end, since in this standard model, nothing can explain the gravitational forces so well described by general relativity.
There is therefore work to be done before arriving at the Theory of Everything. This is why researchers carry out experiments like these, they allow them to ensure their back in testing the limits of their current models. And it’s not just for the sake of doubting; the missing pieces of the puzzle are hiding presumably in these still obscure breaking points.
“It’s important to continue to place the most demanding tests on general relativity, to find out where and when it crumbles.”, Explains its English co-author Robert Ferdman. “Finding the slightest deviation from general relativity would be a major discovery that would open new doors in physics, far beyond our theoretical understanding of the universe. And that may one day allow us to discover a unified theory of the fundamental forces of nature.”Ferdmann concludes thoughtfully.
The text of the study is available here.
