Is General Relativity ‘Wrong’?

The General Theory of Relativity is the currently accepted model of gravity. But, many Physicists, who are a big fan of the quantum field thory, are trying to prove it wrong (although they are always unsuccessful in this task).

All the experimental evidences confirm Einstein’s general relativity. In the recent days, you may have read some articles like this one, ‘saying’ that Scientists (Professor Andrea Ghez and team) disprove Newton’s Theory of Gravity and dimiss it.

Read the full article about Einstein’s Theory of Relativity (both Special and General) by clicking here.

I don’t know what actually they are trying to say or prove because Newtonian Gravity was disproved some 100 years ago by Albert Einstein by presenting the revolutionary general theory of relativity. After that, general relativity have been confirmed a number of times in a number of different types of researches and experiments.

Actually, the equation Newton gave us in his theory of gravity give almost correct results for weak gravitational fields, and, as it is much simpler than the equations of general relativity, we still use it for all the practical purposes.

Read the full article about Newtonian Physics by clicking here.

So, firstly we should know what Professor Ghez (of the University of California) actually did. She actually did the ‘most comprehensive’ test of the general theory of relativity near the black hole at the center of the Milky Way.

“Einstein’s right, at least for now. We can absolutely rule out Newton’s law of gravity. Our observations are consistent with Einstein’s theory of general relativity.”

Said Professor Ghez.

So, she didn’t concluded anything ‘new’. Everybody knew (and know) that Einstein is right and Newton was somewhat wrong.

“However, his theory is definitely showing vulnerability. It cannot fully explain gravity inside a black hole, and at some point we will need to move beyond Einstein’s theory to a more comprehensive theory of gravity that explains what a black hole is.”

Professor Ghez added.

So, in these statements also, she didn’t say anything new. We know that both General Relativity and Quantum Physics don’t ‘work’ inside a black hole. This is because of the reason that the singularity of a black is the ‘meeting point’ of a very strong gravitational field (which is explained by General Relativity) and a very small size (explained by Quantum Physics).

So, we have to apply both General Relativity and Quantum Physics at this point. But, when this two theories are applied at the same time, we get very strange results, like the whole universe should collapse instantly!

Professor Ghez made direct measurements of the phenomenon near a supermassive black hole, and said that Einstein’s theory is the best description of how gravity works (in contradiction of her own words!)

“The laws of physics, including gravity, should be valid everywhere in the universe”, said Ghez, who added that her research team is one of only two groups in the world to watch a star known as S0-2 make a complete orbit in three dimensions around the supermassive black hole at the Milky Way’s centre.

The full orbit takes 16 years, and the black hole’s mass is about four million times that of the Sun.

The researchers say that their work is the most detailed study ever conducted into the supermassive black hole and Einstein’s theory of general relativity.

The key data in their research were the spectra that the team analysed this April, May and September as the star made its closest approach to the enormous black hole.

Spectra of stars, in the easiest words, can be defined as the “rainbow of light from stars”. It show the intensity of light and also the chemical composition of a star.

These data were combined with measurements Ghez and her team have made over the last 24 years.

Spectra—collected at Hawaii’s W.M. Keck Observatory using a spectrograph built at UCLA by UCLA’s Professor James Larkin, provide the third dimension, revealing the star’s motion at a level of precision not previously attained.

Professor Larkin’s instrument takes light from a star and disperses it. (similar to the way raindrops disperse light from the sun to create a rainbow).

Ghez said,

“What’s so special about S0-2 is we have its complete orbit in three dimensions.”

“That’s what gives us the entry ticket into the tests of general relativity.”

“We asked how gravity behaves near a supermassive black hole and whether Einstein’s theory is telling us the full story.”

“Seeing stars go through their complete orbit provides the first opportunity to test fundamental physics using the motions of these stars.”


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Conclusion

So, what we can conclude from the above discussion is that neither General Relativity nor Quantum Physics is wrong, both the theories are just incomplete. And, Physicists are working to obtain a complete ‘Theory of Everything’.


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References


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Author: Madhur Sorout

Madhur Sorout is currently a fifteen-year-old eleventh-grader from India. His main fascination lies with the subject of physics, mainly in the field of the general theory of relativity and topics related to it like the Big Bang, black holes and the evolution of the universe. He likes to make sense of what he sees in this universe. He has founded the (popular) science website – Maddyz Physics (maddyzphysics.com). He is also a physics and astrophysics editor for the Young Scientists Journal. He loves to read books by Stephen Hawking, Neil deGrasse Tyson and other authors (and physicists). Inspired by their work, Madhur wrote Astrophysics Simplified: A Simple Guide to the Universe. He started to write this book when he was 14. A diehard fan of fiction, Madhur also likes to play cricket and wants to continue down the route of research in theoretical astrophysics.

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