The Expanding Universe

[Guest jamongo]

I was reading a bit on the Large Hadron Collider, and a question came to mind.

When two particles collide is it possible to measure the speed of the issuing debris?

If so, as the distance increases from the point of collision, is this speed increasing or decreasing?

It strikes me that the various descriptions of the "Big Bang" are similar to the collision of particles.

Just a random, possibly silly thought.

[CraigD]

I was reading a bit on the Large Hadron Collider, and a question came to mind.

When two particles collide is it possible to measure the speed of the issuing debris?

Yes. The details of how are complicated – they’re what folk get PhD’s and postdoc training in experimental physics to learn – but as needed, the instruments around the target in a collider, the LHC or smaller ones, can get a lot of information about the particles they produce.

 

If so, as the distance increases from the point of collision, is this speed increasing or decreasing?

Unless an experiment is carefully designed to do change particles’ speeds, they usually don’t change much. Collision product usually have tremendously high speeds – often 99%+ the speed of light – and the instruments that detect them are small – at most a few tens of meters – so there’s little time or distance for speed changes.

 

When a system is designed to change particles speed, it’s usually to slow, or cool, them, so they can be stored. CERNs “Antimatter factory” is a good example of this.

 

It strikes me that the various descriptions of the "Big Bang" are similar to the collision of particles.

Just a random, possibly silly thought.

While there are similarities, a key difference between conditions shortly after the Big Bang and a particle collision experiment is that space doesn’t expand after the latter, as it’s theorized to have done (and still be doing) after the BB. Check out metric expansion of space at wikipedia for more.

[Guest jamongo]

Thanks for the response. I can see where it would be extremely difficult to measure the speed of the particles, and more so to determine any change in speed. Maybe some day?