Intergalactic Race Shows That Einstein Still Rules

Ponca City, We love you writes "The NY Times reports that after a journey of 7.3 billion light-years, a race between gamma rays ranging from 31 billion electron volts to 10,000 electron volts, a factor of more than a million, in a burst from an exploding star, have arrived within nine-tenths of a second of each other. A detector on NASA’s Fermi Gamma-Ray Space Telescope confirmed Einstein’s proclamation in his 1905 theory of relativity that the speed of light is constant and independent of its color, energy, direction or how you yourself are moving. Some theorists had suggested that space on very small scales has a granular structure that would speed some light waves faster than others — in short, that relativity could break down on the smallest scales. Until now such quantum gravity theories have been untestable because ordinarily you would have to see details as small as the so-called Planck length, which is vastly smaller than an atom — to test these theories in order to discern the bumpiness of space."

Comments

Re:How do they know

[Richard_at_work]

Its also plausable that they left at the same time, and arrived 0.9 seconds apart. How do we tell though?

Re:How do they know

[gnick]

Not true. If we know that the event that generated the rays lasted only 2.2 seconds and we have a theory that would delay one of the rays by more than 3.1 seconds (2.2 + 0.9) relative to the other, we can invalidate that theory. From my understanding, that is exactly the case we're dealing with. You are correct though that this cannot completely validate any specific theory - All it can do is reinforce the assumption that our current theory is more accurate than some others proposed and eliminate some competing ideas.

Re:i'm confused

[Rary]

We know that the pulses were caused by an event that lasted 2.2 seconds, therefore we know that they left anywhere from 0 to 2.2 seconds apart. However, the point isn't to determine a simple boolean result to the question "did they arrive at the same time", the point is to invalidate the predictions of theories. The existing theories predicted that the arrival times of these pulses, having left at most 2.2 seconds apart, would be at a minimum significantly more than 0.9 seconds. However, they were not, therefore the theories' predictions are wrong, and thus the theories are invalid. The one theory that predicted that they would arrive at most 2.2 seconds apart remains — not proven, but still not disproven. That's how science works.