Yet again, predictions made by Einstein’s theories of Relativity have been vindicated.
In this case, two key predictions made by General Relativity…that the spacetime fabric of the universe is distorted by the mass of objects and that this “fabric” is swirled around rotating objects…have been shown to be true in controlled experiments that were 50 years in the making.
You know…..why the hell don’t we just concede that everyone of Einstein’s predictions are true and just go from there?
Why waste the time doing the experiment?…well science doesn’t work that way kids
This latest vindication is especially interesting for two reasons.
One, the idea behind it is so cool and second, the experiment was a tour de force unlike almost any other.
Spacetime is, of course, a fusion of the three spatial dimensions we know and love plus the dimension of time into one all pervading fabric of the universe.
The primary idea here then is that spacetime is affected by anthing with mass. General Relativity predicted that objects with mass would distort this fabric in two ways.
One is the Geodetic effect which is just another way to say that mass warps spacetime. This is actually a valid way to look at gravity. Objects move through spacetime following this warped shape of the universe caused by mass. We interpret this as gravity. I never forgot how Douglas Adams described this inter-relationship in one of his Hitchhiker’s books….(paraphrasing)…massive objects define the shape of the universe and the shape of the universe determines how massive objects move through it.
The canonical mental image of this of course is a bowling ball on a trampoline. The ball changes the shape of the trampoline in a two-dimensional analogue to the way mass changes the shape of spacetime.
The second prediction as to how mass distorts spacetime is called frame dragging.
This describes how the rotation of massive objects can actually turn spacetime into a swirling vortex. Imagine our bowling ball again but this time in a vat of molasses. Rotate the ball and what happens? The molasses is pulled along a bit, following the rotation of the ball.
All these effects that I’m describing are of course incredibly tiny. In fact Einstein himself wrote that
“Their magnitude is so small that confirmation of them by lab experiments is not to be thought of.”
See, he wasn’t so smart after all…silly Einstein
Now to the experiment. It really was a tour de force.
The four little stars of the show are arguably the fused quartz spheres used as gyroscopes that the Guiness Book of Records says are the most spherical man-made objects. They vary from a ‘true sphere’ by only 40 atomic layers.
These gyros pointed the space probe to a star which acted as a reference point. It would always point towards that star unless spacetime was warped by the earth.
Sounds easy right? In fact…this experiment was fiendishly difficult. NASA actually began funding, planning and the building of the Gravity Probe B mission back in 1963. It took all that time to laydown the groundwork and finally lauch the probe in 2004
In fact, 86 Ph.D. theses were created from this project. One hundred Ph.D scientists did their graduate work on this experiment not to mention the several hundred undergrads and over 50 high-school students.
The benefits to date were also not primarily theoretical. Thirteen new spacecraft technologies were required to complete this project. The probe itself is a unique spacecraft that merged the usually distinct instrument, guidance and control functions into a single unifying and unprecendented system.
Other benefits will include a deeper understanding of fascinating cosmic phenomena like black holes and gamma-ray bursts.
Some of this tech has already found its way into ground-breaking applications like NASA’s Cosmic Background Explorer which won scientists the 2006 Nobel Prize in Physics.
Funny how Einstein’s Relativity theories win others Nobel prizes and he never won one for them.
Well, even though it may be relatively safe to assume that Einstein’s predictions will be correct, you can never predict how validating a prediction will benefit us in other ways.