By Scott Sullivan
Editor
Gravity’s Rainbow
Extra! Extra: Could Gravitational-Wave “Memories” Prove Einstein Wrong?
Scientific American gave us this grabber headline recently, claiming Albert Einstein’s 1916 general theory of relativity may soon be refuted. Or maybe not. If there’s one thing I love about science, it is certainty.
Although waves are by definition transitory, Einstein said the universe remembers each ripple by leaving a permanent mark in space, or a fixed distortion in its wake.
So far, this “memory” effect has never been detected. But scientists hope to do so as early as 2035. Fix them up with a research grant to find and distort new data by then,you’ll see.
Einstein predicted vibrations in space would ripple out from any masses accelerating asymmetrically. These could range from emerging black holes to exploding stars to a person spinning around in their office chair. But their force would be too small to ever be detected.
Physicists 100 years later proved Einstein wrong by proving him right: they invented a Laser Interferometer Gravitational-Wave Observatory (LIGO) that did show vibration patterns of black holes merging.
Absent a grant, I made do with a LEGO kit to prove Einstein wrong myself, building a plastic wall to keep out waves of immigrant ants. Then I spun it to say I’d secured our borders, till they crawled over anyway.
Seeking alternate metaphors, I detected when waves wash under buoys the buoys bob briefly closer to each other. Similar distortions of space, said Einstein, create a new round of smaller waves that emanate from the first, bringing objects closer yet.
Each round of waves is weaker than before, but adding them up we arrive at a permanent space distortion. Once the first waves pass, freely-floating objects stay nearer to each other. Golly, permanance! This explains how marriage works, except when it doesn’t.
Einstein’s relativity has frustrated scientists for 108 years by withstanding every test that could invalidate its predictions or find a crack in its calculations. LIGO detecting these waves do exist still fell shy of that.
But a new toy, LISA — the Laser Interferometer Space Antenna, green-lit by the European Space Agency for launch in 2035 — promises to restore their hopes.
Scientists predict LISA will be able to detect gravitational-wave memory by measuring the permanent distortion of space within our Solar System. You know, the one that once ended at Pluto until Pluto was invalidated as just a large rock, not a planet. The end was then edited to Neptune, 2.8 billion miles from the sun.
That’s less than the universal field Einstein had hoped to confirm, but still …
LISA will target waves generated by colliding supermassive black holes down to ones no bigger than an atom’s nucleus.
Why sweat small stuff like that? Ever hear of atomic bombs?
Or, as the headline says, LISA could prove Einstein wrong. Scientists do know relativity is not complete. It does not describe what happens at the centers of black holes or in the first moments of the universe. Einstein’s theory does not get along with quantum mechanics, nor explain dark matter and energy, the twin mysteries which make up 95 percent of the contents of our universe.
Nobels or whistles for everyone if LISA can overturn it. If She doesn’t, we still will be better able to determine when and where supermassive objects, such as black holes, collide. This could be invaluable spurring more speculation and research grants.
“The ultimate lesson from this work,” Scientific American assures us, “is that our mundane conceptions of fixed space are incorrect and incomplete.”
We have no choice but advance our knowledge and, at the same time, sense of wonder.
Science marches on.
PS – Election post-mortems gave way last Sunday to a rainbow outside my den window. I could see an arc between flying raindrops and fleeing leaves, then a half-moon through blowing cloud out my other window.
I received the poem and picture printed at upper right about Saugatuck’s beloved willow tree and felt glad our priorities were once again right. Life was moving on.
