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one for the maths gurus

proflight2000

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GazOC

GazOC

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I think they use the balloon example. When you blow one up any marked points are still in the same place on the balloon but get further apart as the baloon expands. The example is missing a dimension but its easier to see the principle that way.

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dazza1639

dazza1639

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My understanding was that the speed of light stays the same no matter what, the distance between the points remains the same so the only variable left is the time taken as time is not constant it changes relative to the viewer and the speed in which the are traveling.

Darren

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Kaptain Klevtsov

Kaptain Klevtsov

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Well Gaz, I got the baloon example, but I thought it referred to the stuff moving apart and light would travel through the empty bits unmolested ny the movement of all the stuff. Space surely cant get bigger, there's nothing there to get bigger, only gaps where there's no stuff.

Captain Chaos

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GazOC

GazOC

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CC,

I read a few books on the subject but TBH I have to take most of it at face value. Inflation seems to be the popular theory, where space is expanding as it accounts for the fact the the background radiation is constant throughout the cosmos. It also models that the cosmos is expanding in all directions, not from a central point which is also what we see.

Like I say, read but not always comprehended.... :)

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themos

themos

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Space surely cant get bigger, there's nothing there to get bigger, only gaps where there's no stuff.

I am afraid that physicists have found a way of describing "space that gets bigger" and cosmologists use it all the time.

It all starts with good old Pythagoras theorem. Then, instead of x2+y2, you put in something like R(t)*(x2+y2). Plug that into Einstein's field equations and see how the matter-energy distribution will determine the function R(t).

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themos

themos

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However, is light classed as matter? :?

There used to be a distinction between matter and "fields" like light (it's the electromagnetic field). It's better to think of everything as fields, so you have the photon field, the electron field, the neutrino field, the proton field, the quark field, the gluon field, the Higgs field. Some fields are special in the sense that they correspond to particles with zero rest mass. These particles are condemned to travel at speed c (the speed of light) with respect to any observer . Light is the only known field that manifestly does this (gravitons may also do it and gluons kind of do it but only at the sub-nucleonic level).

A field "excitation" of frequency ? has energy E=h*? (h is the famous Planck constant = 6.63 × 10-34 m2 kg / s, or 4.13 electron-Volts/PetaHertz).

The rest-mass of a field contributes energy E=m*c2 for every particle of mass m, so an electron's mass is about half-a-million electron-Volts of energy.

Energy of all forms counts for creating gravitational effects (we think).

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Cloudwatcher

Cloudwatcher

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There you go! Ask a silly question and you get a silly answer!

I mean 6.63 x 10 to the power of 34 alone produces more zeros than I care to think about!

There is a Third Way. The barman, down our local, a gent of vast intellect, say the only

sensible way to measure Light is in a pint glass with a Vodka chaser!

Could be a long and interesting research project there! Who knows,might even get Lottery funding!!!

CHEERS :)

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Cloudwatcher

Cloudwatcher

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The calculator used was one of those old Texas Instrument jobs. You know the

one with cos.sin.& tan and umtyfour other buttons on.

I'm a Mac user rather than PC and confess I haven't tried the on-board calc.

Might give it a go. Then again...........

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