In 2015, scientists observed gravitational waves.
For the first time ever, we could actually ‘see’ the distortion of space-time as
it reacted to huge events in space, like the collision of black holes.
This was one of the most exciting physics discoveries of our age, and the team involved
were even awarded the Nobel Prize in physics last year....so why is this discovery now
being called into question?
Ok, this is some pretty earth-shaking, heck, even space-shaking drama.
Scientific tea, if you will.
Some scientists are now questioning the methods used at the Laser Interferometer Gravitational-Wave
Observatory, which we all commonly know as LIGO, where gravitational waves were first
observed.
It’s kind of like a really polite, but really nitpicky episode of the real housewives of
astrophysics.
Just so we’re all clear, detecting gravitational waves is really freakin’ hard, which is
one of the reasons why it was such a big deal.
When black holes, for instance, collide with each other, they can merge, and in that merging
process, some of the energy of that collision is released into the universe as gravitational
radiation.
This is essentially a ripple that distorts the earth by about the width of an atomic
nucleus.
So you can see why it was impressive when the LIGO Scientific Collaboration said they
were able to detect this wave.
But the minuteness of a gravitational wave is not the only problem LIGO faces.
Yes, the detector has to be unprecedentedly sensitive to observe and measure a gravitational
wave, but it also has to be able to pick out that wave from the endless buzz of other background
noise, like the natural vibration of the earth itself.
So, in order to make sure that what they’re measuring is really a gravitational wave and
not something else, LIGO has two independent sites: one in Louisiana and one in Washington.
Between these two detectors, almost a continent away from each other, there shouldn’t be
any overlap in their noise patterns, but the wave--the signal they’re actually looking
for, should show up in corresponding places at both observatories.
So we should be able to easily identify what is noise--all that stuff that doesn’t match
up between detectors.
Then when you subtract that away you’re left with only the signal--the gravitational
wave.
That’s the ideal, anyway.
And this is where the friendly collegial discussion starts.
A team of physicists at the Niels Bohr Institute in Copenhagen made their own analysis of the
LIGO’s freely and publicly available data and they take issue with some of the methods
used.
When the Danish team re-analyzed LIGO’s data, they found that while the wave signal
matched up between the two detectors, so did some of the noise.
Which it shouldn’t, because the noise is supposed to be random and independent between
observatories.
Which introduces the problem that maybe, the signals that LIGO picked out are...less clear
than the world would like to believe?
As you can imagine, there’s been a LOT of back and forth on this.
The LIGO team has responded to the Danish team’s concerns by basically saying that
the methods and computer programs they used to extract the original data are extremely
complicated and the Danish team wasn’t using them correctly.
Which then prompts responses from some people (like me) who say, “Ok, but even if your
science is right it should be at least be repeatable for other teams in your field,
LIGO, ya diva”.
And the Danish responded by saying “thank you for teaching us more about your computer
program, we re-did our analysis and we still think your results are funky”
And here’s the thing.
This kind of kerfuffle...has happened before.
Einstein predicted gravitational waves’ existence in 1916, and if we’ve actually
detected them, we’ve now observed his theory of general relativity in the tangible, physical
properties of our universe.
Which helps us better understand gravity and where it comes from and why it behaves how
it does--pretty huge and important mysteries we’re still facing in physics.
Since Einstein’s original proposal, several other noteworthy experiments have tried to
detect gravitational waves, with two standouts claiming that they had, to much excitement...only
to then be debunked, very publicly.
Rather embarrassing for all involved.
So it’s right to be skeptical, especially about something as huge and groundbreaking
as this particular phenomenon.
But.
When all is said and done and when the dust settles around this flurry of agitated physicists,
even in the most extreme scenario, scientists agree that we’ve still definitely detected
gravitational waves.
This is the real deal this time, guys.
It’s not that LIGO didn’t detect the waves, it’s simply that their analysis may need
improvement.
And if it remains unimproved, these methods could be introducing room for error that no
one wants to have to deal with.
This is the scientific process in action.
As you watch this video, LIGO is putting together a detailed document revealing how they got
their results, so what could have been a potential rift has instead opened up some important
dialogue in the scientific community and will hopefully be productive and just help us do
the science better.
And as of this early December, LIGO detected four more black hole mergers while looking through their previous observational data.
he researchers say that these dectections weren’t as “loud” and needed more careful analysis.
With that in mind, maybe this new paper will help qualm any debates about their techniques.
As dramatic as it sounded like it was gonna be, I don’t think it’s gonna
provide enough material for an ultra-exciting Hollywood reimagining.
At least not yet.
I guess we’ll see what happens.
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