posted on Feb, 1 2008 @ 07:54 AM
The oldest light is the cosmic microwave background radiation, which is the light from the big bang, actually its the light that was around at the
point that the universe became transparent.
The CMBR is 13.7 billion years old, ie. those photons have been travelling for that time without hitting anything.
However due to the expansion of the universe the photons are very stretched, so although they started as high energy photons, eg. light, UV, x-rays,
they are now very low energy photons (from our point of view).
I suppose that given enough time they will become undetectable as their frequency decreases further.
But if you want to blow a fuse in your brain, think about it from the photons point of view. Because the photon travels at the speed of light, it
takes 0 time to get anywhere, the photon arrives at the same time it leaves, ie. it connects the detector in orbit around earth today with the
particles that existed 13.7 billion years ago, even though the detector didn't exist then. Kind of suggests that time is weirder than anyone can