Speed of light

[Steak & Cheese]

I was listening on the radio yesterday to a program about the LHC and it mentioned that the atomic particles would be travelling at about 20kph less than the speed of light! Why not just speed them up a bit more and have them travelling at the speed of light?

Is it possible for anything to travel at the speed of light? or faster than the speed of light?

[parapaul]

Yes. Light.

[sadako]

Tachyons can also at least do c.

[Einion Yrth]

sadako said:

Tachyons can also at least do c.

Tachyons must do more than c, only massless particles may travel at c. Currently, the only known massless particles are gauge bosons: the photon (carrier of electromagnetism) and the gluon (carrier of the strong force). However, gluons are never observed as free particles, since they are confined within hadrons.

Neutrinos were, until recently, thought to be massless; but, because neutrinos change flavour as they travel, they must have mass.

ETA: Tachyons are also entirely theoretical, never having been observed - indeed their observation presents something of an issue even if they do exist.

Edited by Einion Yrth on Tuesday 9th September 06:40

[TimJMS]

What's the deal with the Universe being between 12 - 20 billion years old, and 90 billion light years across?

A lot of matter has to be traveling considerably faster than light speed.

[CommanderJameson]

TimJMS said:

What's the deal with the Universe being between 12 - 20 billion years old, and 90 billion light years across?

A lot of matter has to be traveling considerably faster than light speed.

Where does the 90 billion light years across come from?

[toastboy]

Einion Yrth said:

Neutrinos were, until recently, thought to be massless; but, because neutrinos change flavour as they travel, they must have mass.

True, I saw a strawberry one change to butterscotch just yesterday.

[TimJMS]

CommanderJameson said:

TimJMS said:

What's the deal with the Universe being between 12 - 20 billion years old, and 90 billion light years across?

A lot of matter has to be traveling considerably faster than light speed.

Where does the 90 billion light years across come from?

why that mine of useful accurate information known as Wikipedia of course

Specifically : ^ Lineweaver, Charles; Tamara M. Davis (2005). "Misconceptions about the Big Bang". Scientific American. Retrieved on 2007-03-05.

Edited by TimJMS on Tuesday 9th September 07:00

[Vipers]

[quote=Steak & Cheese]
Is it possible for anything to travel at the speed of light?
[/quote]

Electromagnetic radiation travels at the same speed as light, ie radio waves.

[CommanderJameson]

TimJMS said:

CommanderJameson said:

TimJMS said:

What's the deal with the Universe being between 12 - 20 billion years old, and 90 billion light years across?

A lot of matter has to be traveling considerably faster than light speed.

Where does the 90 billion light years across come from?

why that mine of useful accurate information known as Wikipedia of course

Specifically : ^ Lineweaver, Charles; Tamara M. Davis (2005). "Misconceptions about the Big Bang". Scientific American. Retrieved on 2007-03-05.

I'm out of date, it would seem. I've been wandering around under the misapprehension that the universe was about 15 billion light years across.

A quick Google for "size of the universe" turns up this link which explains how the universe got so big without having things travel faster than light.

[Drop Test b3nxj]

TimJMS said:

What's the deal with the Universe being between 12 - 20 billion years old, and 90 billion light years across?

somthing i have wondered,

once you reach the end of your 45billion78billion light year journy (thats if you were in the middle of the universe), whats after that???


edit 156 billion lightyears across

Edited by Drop Test b3nxj on Tuesday 9th September 08:03

Edited by Drop Test b3nxj on Tuesday 9th September 08:05

[groucho]

Drop Test b3nxj said:

TimJMS said:

What's the deal with the Universe being between 12 - 20 billion years old, and 90 billion light years across?

somthing i have wondered,

once you reach the end of your 45million light year journy (thats if you were in the middle of the universe), whats after that???

Room 101

[TheCaseAce]

In answer to the OP - it's impossible to get anything with mass to the speed of light, because the amount of energy required to get it there rises (exponentially?) to infinity.

In order to make a particle travel at the speed of light you need infinite energy - i.e. it's impossible.

EM waves (including Light) can travel at this speed because they have no mass.

[JRM]

TheCaseAce said:

In answer to the OP - it's impossible to get anything with mass to the speed of light, because the amount of energy required to get it there rises (exponentially?) to infinity.

In order to make a particle travel at the speed of light you need infinite energy - i.e. it's impossible.

EM waves (including Light) can travel at this speed because they have no mass.

So why is speed of light the maximum achievable speed? I understand that absolute zero exists when all electrons etc stop moving and have zero energy, but I just wondered why c (or slightly less) is the maximum speed anything with mass can travel?
Has anyone tried it downhill with a tail wind?....

[dougc]

Drop Test b3nxj said:

TimJMS said:

What's the deal with the Universe being between 12 - 20 billion years old, and 90 billion light years across?

somthing i have wondered,

once you reach the end of your 45billion78billion light year journy (thats if you were in the middle of the universe), whats after that???


edit 156 billion lightyears across

Do you mean, what is the 'other side' of the edge of the universe? What would you see if you looked over the wall?

There are theories that there exists a number of universes (Multiverse). Perhaps over the wall is one of those?

Personally I'm inclined to believe that the universe is still expanding into nothing.

I love the idea of nothing. Try and explain it to someone. Nothing is exactly that. Nothing. No light, no time, no existence of anything.

[Alex]

Light is so fast, it's a wonder we ever see it at all.

[rhinochopig]

The speed of light varies - depends on the material it is passing through. So you can actually exceed the speed of light, hence...

http://en.wikipedia.org/wiki/Cherenkov_radiation

[FourWheelDrift]

Drop Test b3nxj said:

TimJMS said:

What's the deal with the Universe being between 12 - 20 billion years old, and 90 billion light years across?

somthing i have wondered,

once you reach the end of your 45billion78billion light year journy (thats if you were in the middle of the universe), whats after that???


edit 156 billion lightyears across

http://www.youtube.com/watch?v=OcTHBOjnUss

[Dr John]

Drop Test b3nxj said:

once you reach the end of your 78billion light year journy , whats after that???

Travelling at greater than the speed of light you will be travelling back in time and will eventuelly come to The Big Bang and the start of time itself.

[Einion Yrth]

JRM said:

TheCaseAce said:

In answer to the OP - it's impossible to get anything with mass to the speed of light, because the amount of energy required to get it there rises (exponentially?) to infinity.

In order to make a particle travel at the speed of light you need infinite energy - i.e. it's impossible.

EM waves (including Light) can travel at this speed because they have no mass.

So why is speed of light the maximum achievable speed? I understand that absolute zero exists when all electrons etc stop moving and have zero energy, but I just wondered why c (or slightly less) is the maximum speed anything with mass can travel?
Has anyone tried it downhill with a tail wind?....

This is why, but you're not going to like it.