Gravitational Waves
It is the
biggest news in physics science since the discovery of the Higgs Boson a
couple of years back: the confirmation of the existence of gravitational waves.
What the hell is that? And why is it a big deal?
This blog is
based entirely on Nicolo Twilley’s awesome
article on the topic. So here we go…
So what are
gravitational waves? An analogy will help:
“When two black holes orbit each other,
they stretch and squeeze space-time like children running in circles on a
trampoline, creating vibrations that travel to the very edge; these vibrations
are gravitational waves.”
Actually, any
two objects can (and do?) generate these waves; but unless the objects are as
massive as black holes, those waves are too tiny to detect. To understand how
tiny these waves are, just look at how much energy had to be generated for the
waves to be (finally) detectable:
“In the fraction of a second that it took
for the black holes to finally merge, they radiated
a hundred times more energy than all the stars in the universe combined…
The
waves rippled outward in every direction, weakening as they went.”
A billion years
later, those waves finally reached earth. And were detected.
Now let’s move on
to how awesome a feat of engineering detecting these waves was. As David Reitze
put it:
“We’re saying that we made a measurement
that is about a thousandth the diameter
of a proton, that tells us about two black holes that merged over a billion
years ago.”
You bet the data
was re-checked and re-checked and re-checked. Which is why a measurement that
happened on 14th September, 2015 was officially announced only now.
When the system was being built, it was so ambitious that Rich Isaacson
describes it thus:
“It was a couple of maniacs running
around, with no signal ever having been discovered, talking about pushing
vacuum technology and laser technology and materials technology and seismic
isolation and feedback systems orders of magnitude beyond the current state of
the art, using materials that hadn’t been invented yet.”
Not to mention
the $275 million price tag!
As to who
predicted their existence, it was that man: Einstein. Big surprise! A hundred
years ago, based on (what else?) the theory of relativity.
So why is this a
big deal? Well, for starters, it confirms yet another weird thing predicted by
the theory of relativity (gravitational waves). It also confirms the existence
of black hole pairs, something never proven before. And:
“The LIGO scientists have extracted an
astonishing amount from the signal, including the masses of the black holes
that produced it, their orbital speed, and the precise moment at which their
surfaces touched.”
Put differently,
this opens up a whole new way we can observe the universe. Until now, all our
observations were based on the electromagnetic spectrum: visible light, x-rays,
ultraviolet rays and gamma rays. Now we have a “completely new kind of
telescope”, as Reitz puts it. Or as the article puts it:
“If what we witnessed before was a silent
movie, (Janna) Levin said, gravitational waves turn our universe into a talkie.”
The newspapers couldn't provide me with enough material for me to grasp the full detail. (Of course only physicists, and that too those at very advanced levels, can understand this thing in full. What I mean is "as full as a layman with great interest in physics can understand.)Your elaboration is good. I get the picture now.
ReplyDeleteIt's amazing that Einstein started with an attempt to explain away one single anomaly in light propagation through what is now called the "special theory of relativity". The genius that he was, he refused to stop there. He extended his "special" thing into a "more broad based thing" which is known as the "general theory of relativity. The remarkable thing is that these two together went far beyond what Einstein could have imagined even perhaps in his dream as their relevant or application domain. After a hundred years the theory is still growing strong.
Actually before Einstein astrophysics was 99% ignorance and 1% knowledge. After Einstein, astrophysics seems seems to have transformed into 75% knowledge and 25% ignorance. (Of course the truth is this: plenty of observations expanded the domain of astrophysics further to the postulation of Einstein's theory, in that sense it not all Einstein's contribution here. But all observations seemed to not only support Einstein's theory but seem to need it invariably!)
I find all this thrilling. I know for sure that most of mankind would not even be able to appreciate this gravitation wave business because without fair knowledge of physics nothing would make any sense. Lay people may wonder only as much as they wonder how a television works! The theory of relativity is far subtler than how a television works though! :-(
Hats offs to Einstein I should say; but I hesitate because I never wear any hat so I can never take it off! I may have to bring my hands together and say, "Namaste" with a head bow perhaps, in the Eastern style! :-)