Expert: Expert - 11/4/2009

Question
if we go to to a faraway place maybe to another galaxy at the speed of light, i know that sound travel slower then light so we are on a far place, can we hear the sound made by the prehistoric dinosaurs if the time is right assuming that the sound is loud enough and can travel through space.

Answer
Three problems with this idea:

1) Sound can not travel without an atmosphere (or some other medium). Those explosions and "wooshing" sounds you hear in space movies are completely bogus. Thus, the sounds made by anything made on Earth -- including dinosaurs -- could never be heard outside our atmosphere.

2) Sound energy rapidly denigrates into heat. That's why you aren't be able to make out the sound of someone talking a kilometer away, no matter how sensitive your equipment. Thus, even being ten kilometers away from a dinosaur would mean you wouldn't be able to discern any meaningful sound. Now imagine being 10^15 kilometers away (about 100 light years) -- the distance you would need to be in order to hear a sound from 100 million years ago.

3) Let's say that sound DID travel through space and did NOT dissipate over 10^15 kilometers of travel. Trying to separate the sound of a dinosaur from all other sounds floating around the nearby stars would be impossible. Our Sun alone would be releasing FAR more sound than that from all the dinosaurs on our Earth -- and then add all the sound from the other stars in the intervening 100 light years. It'd be like trying to make out a whisper in London while standing in New York on Times Square on New Years Eve. The signal to noise ratio would just be too large.