It's relative. Astronomers have been measuring spin precession in an eclipsing pair of pulsars.
Credit: Daniel Cantin/McGill University
Posted on 07/05/2008 5:49:29 PM PDT by neverdem
It's relative. Astronomers have been measuring spin precession in an eclipsing pair of pulsars.
Credit: Daniel Cantin/McGill University
As if his reputation needed cementing, astronomers have confirmed Albert Einstein's status as a supergenius once more. Studying a unique pair of pulsars--small and extremely dense leftovers from supernova explosions--researchers have measured an effect that was predicted by Einstein's 92-year-old general theory of relativity. The result, they report tomorrow in Science, is almost exactly what the famous physicist had foreseen.
In Einstein's relativistic universe, matter curves space and slows down time, and the speed of light remains the only constant. But those are the big effects. The theory of relativity also includes some more esoteric details, one of which is called spin precession. The idea goes like this: Two massive bodies orbiting near each other will warp space enough to disturb the central axis around which both are moving, causing them to begin wobbling just like spinning tops. Strong gravity creates this so-called precession, and the more massive the objects, the easier the precession is to observe.
It's not an easy theory to test. Researchers need two very dense objects orbiting very close together, and they have to be able to detect what is going on between them. Black holes are dense, but their event horizons preclude observations. The lack of candidates and telescopic power had frustrated astronomers for years, until the discovery in 2003 of a particular pair of pulsars. These asteroid-sized objects pack sunlike masses, extremely small orbits, and incredibly fast spins. They also emit powerful and ultraregular radio signals that are easily detectable with Earth-based dishes. Most important in this case, one pulsar eclipses the other briefly every couple of hours. That's key to detecting precession, because during each eclipse astronomers can determine the precise angle of the radio signal and therefore the pulsar's wobble over time.
For the past 4 years, an international team has been carefully tracking the signals of one of the pulsars and monitoring the signals' direction during eclipses--a observational technique "that has never been employed before," says astrophysicist and co-author Rene Breton of McGill University in Montreal, Canada. The researchers determined that the precession of the pulsar's orbital axis advances by 4.77 degrees per year, plus or minus 0.66 degrees. Calculations based on Einstein's theory predicted it should advance by 5.07 degrees per year, well within the margin of error.
"It's bang-on," says astrophysicist and Nobel laureate Joseph Taylor of Princeton University. "Einstein's theory passed the test this time," agrees astrophysicist Fotis Gavriil of NASA's Goddard Space Flight Center in Greenbelt, Maryland, who praises the study's "amazing high-precision measurement." So is Einstein's reputation secure? Says Gavriil, "Only with experiments like this will we know for sure."
Has anyone ever wondered why Einstein didn’t get a Nobel Prize for his theory on relativity?
It's constant only going through a vacuum. It gets bent and slowed down, i.e. refracted, going through various types of matter.
Is there something special about photons within the universe of particles?
It doesn't have mass, but it has energy according to its wavelength when it behaves like a wave.
Is it the fact that humans have given the effect of photons the name “light” and found that the processing of light (”sight”) is the most useful of the human senses for survival?
That's a judgment call.
Or is it because “light” is the first thing God created?
I'll take a pass on Scripture.
Tom is a former director of the Naval Observatory and a major sort of an expert on the subject; what exactly are YOUR credentials??
Einstein's theories (especially General Relativity) have passed rigorous test after rigorous test for close to a century.
No. This is well known.
I favor efforts to deconstruct Einstein's relativity, however, crackpots need to stand aside.
He also made some prescient observations about dilettantes. Perhaps he saw you.
IINM, in the first decades of the Nobel Prizes, the prize for physics was only awarded for applied (as opposed to theoretical) physics. So after the Eddington expedition validated his theory of relativity (i think the General Theory, but i’m not certain), the Nobel folk awarded the prize to him based (officially, at least) on his work on the photovoltaic effect, which he did in 1905.
The result... is almost exactly what the famous physicist had foreseen.Wow, talk about high precision. /snark
Article was a big mess of worms, no?
Incorrect. If that were the case, then gravity would not bend light. Since it it measurably true that gravity does bend light, the speed of gravity is faster than the speed of light.
How much faster, I do not know. But it is faster.
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