Gravity Has Been Constant for 9 Billion Years

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You might have read the title of this article and thought, "Duh, gravity is a constant."

Indeed, we know that gravity is the force that keeps us from floating away every second of every day, so we do know it’s still working. But there is new evidence suggesting that the force could be changing, which led to an investigation into the new theory.

Dr. Michael Murphy from Australia’s Swinburne University has co-authored several papers discussing the the changing nature of “α”, a fine structure constant that controls the strength of electromagnetic interactions. While Murphy is investigating the changing forces of the universe, his colleague, Professor Jeremy Mould at the Center for Astrophysics and Supercomputing, has studied if the attraction force between massive objects might be altering as well.

Mould and PhD student Syed Uddin took a look at 580 Type la supernova explosions, which occur when a white dwarf star takes in too much material from a companion star and explodes from reaching its critical mass. “This critical mass depends on Newton’s gravitational constant G and allows us to monitor it over billions of years of cosmic time-instead of only decades, as was the case in previous studies,” states Mould. “Looking back in cosmic time to find out how the laws of physics may have changed is not new. But supernova cosmology now allows us to do this with gravity.”

Thankfully, they could find no evidence of variation in the mass that triggers a la type supernova, which means that gravity hasn’t changed in the past 9 billion years. Or, at the very least, if it is changing, it’s changing at a rate we can’t feel. Mould and Uddi have stated that if G is changing, it’s changing less than 0.00000001 percent per year.

Since we are still firmly on the ground, we already know that gravity is still working the way we expect it to, but what do you think about the findings? Do you think gravity could be changing, even at an infinitesimal rate? Talk about it below!


Image: NASA

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