Beyond our galaxy, Einstein still rocks

I am writing this exactly 131 years after Albert Einstein was born upon learning that a Filipina scientist looked at the stars far beyond our own galaxy and found that Einstein rocks, even out there. Reinabelle Reyes, an astrophysicist at Princeton University, is the lead author in a paper published last week in the journal Nature entitled “Confirmation of general relativity on large scales from weak lensing and galaxy velocities.” She and her team took Einstein’s idea and tested if it would still hold true if we apply it even to distances beyond our own galaxy.

Einstein’s theory of general relativity published in 1905 is a sweeping explanation of what gravity is. Before Einstein, Newton’s explanation of gravity was that it was a force between any objects that have mass. But Einstein re-examined that idea and said that gravity being a force does not fully capture what gravity really is. Einstein then re-defined gravity as a shape, basically the shape made by “space” and “time” not as two distinct dimensions but intricately entwined in what he called “curved spacetime.” It is one of the most powerful and elegant ideas that has swept science in its history.

The Theory of General Relativity is no longer the theory as most people define “theory.” Most people think a “theory” is a title that ranks below proven scientific truths. In science, that is not so because it is okay to call a theory still a theory even if it has been proven over and over again. Scientists just do not always bother to change the label. Thus, a “theory” in science is not simply an educated guess but a sweeping explanation of a natural phenomenon. After Einstein posed his Theory of General Relativity in 1905, it was subsequently proven in landmark tests and even if we still refer to it as a theory, we no longer mean “theory” equals “ just “a mere possibility.” The same goes with the Theory of Evolution. Evidence for evolution lurks inside your own bodies and everywhere else around you and even if you think it is still only a “theory,” it does not matter because it is what nature really does anyway.

There have been three tests that proved Einstein’s idea that gravity was a shape warped by the mass of objects. There was that test in done in Harvard, where they experimented and indeed demonstrated that an atomic clock is slowed down by the Earth’s gravitational field. Another test was with the planet Mercury which does not have a fixed orbit. Imagine a round clock with many points that you can trace forming a round shape. The orbit of Mercury around the very massive Sun is not fixed; instead, it moves like a spinning ring that also rotates. Scientists examined this strange orbit of Mercury and in order to account for its full revolution, Einstein could only be right in that space-time is curved. That meant that Einstein’s idea also holds in the solar system and not just on Earth. There was also the test during an eclipse, where they saw light from a distant star bend as it drew closer to our massive Sun. Light bending could only have meant Einstein’s curved space-time is right even within the Milky Way. Now comes this test by Ms. Reyes and her team which looked at galaxies beyond our own.

Her team looked at a total of over 70,000 galaxies! They used a measure that takes into account gravitational lensing, galaxy clustering and structural growth rate. Gravitational lensing is a way of looking at how light is bent around massive objects such as stars and galaxies. Galaxy clustering refers to how groups of galaxies form because of gravitational attraction and structural growth rate refers to how these heavenly superbodies grow over time. By coming up with a measure that takes into account all these parameters, the group was able to prove that Einstein’s idea of curved spacetime still reigns even 3.5 billion light years away!

About five years ago, I wrote a column paying tribute to a long-time director of the Manila Observatory named Fr. Victor Badillo, S.J. In my interview, I asked him if he were confident that astronomy would still inspire others when there are so many things that keep us glued to problems only on the ground. He replied with certainty: “There are others who are still looking up.” I think Fr. Badillo, who has been ill for years now, would be very happy to know about Reinabelle, a graduate of Philippine Science High School and Ateneo de Manila, and her passion for looking up to the heavens and understanding it bit by bit. Indeed, some are still looking up.

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