I rather like this science meets fiction article about the Large Hadron Collider, and the current spin-off Sci-Fi and thrillers with presumably more to come.

http://www.timesonline.co.uk/tol/news/science/biology_evolution/article6879293.ece

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And, from the bottom, a quote from Brian Cox, professor of particle physics at Manchester University,
“However, if time travellers do break into the LHC control room and pull the plug out of the wall, then I’ll refer you to my article supporting Nielsen’s theory that I wrote in 2025.”

Intriguing

Sarah

I have to admit, I've found myself speculating along similar lines about the LHC. But why would nature be so specific as to target the machine, rather than, say, Professor Higgs, who came up with the mathematics which suggested the existence of a Higgs boson?

Besides which, if there really is a Higgs boson which gives everything mass, then the LHC won't be doing anything except detecting a particle that is already present. If nature hates the particle, why doesn't the whole Universe cease to...

Lol, Alex.
Presumably they didn't target Prof. Higgs because he wouldn't be the only one searching for the particle, and presumably the travellers from the future have something against murdering their ancestors, whereas making a machine breakdown is a far easier option.

I once heard an intriguing idea about time travel into the past. A colleague of mine at Marconi Space Systems suggested that, maybe, it would only be possible to travel backwards in time if one also were forced to move through space to such a distance that it would not be possible to return to one's point of origin within the amount of time by which one had moved.

For example, if you were to travel 1 year into the past, you would end up at least 1 light-year away from where you started. Since travelling 1 light-year would require a whole year, even at the speed of light, this would make it physically impossible for the "Grandfather Paradox" to happen.

(It's worth bearing in mind, though, that even if this were the way the laws of time travel had to work, there's probably no law in physics that says that all of the atoms in your body/spacecraft/etc. have to travel in the same direction. Captain Janeway beware!)

Alex

I've just about finished my first attempt at reading Prof Cox's book - 'Why does E=MC2". I say first attempt as i'm going to have to read some of it again to try and get my head around it.

The world at a quantum level is a very wibbly wobbly place!

The Elegant Universe: Superstrings, Hidden Dimensions and the Quest for the Ultimate Theory by Brian Greene

This one worked for me.

chris

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http://www.amazon.co.uk/Elegant-Universe-Superstrings-Dimensions-Ultimate/dp/009928992X/ref=sr_1_1?ie=UTF8&s=books&qid=1260314811&sr=1-1

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Ignore the first link.

I read Terry Pratchett - works for me

Sarah

Looks a very interesting read, Chris, thanks for drawing our attention to it. I've added it to my wish list, but it'll be a while before there's a gap in my reading list for it.

If anyone is interested in a relatively maths-free explanation of relativity, I would recommend the following, by Albert Einstein himself:

http://www.amazon.co.uk/gp/product/0415253845/ref=sib_rdr_dp

Before I read this book, I'd had real problems getting my head around the concepts of the subject. Halfway through the first half, though, time-dilation and length-contraction suddenly became blindingly obvious consequences of the central assumption of relativity - that the speed of light is the same for all observers.

Alex

Thanks Chris.
As I understand it, if one could travel faster than the speed of light (and take along a very large telescope) one could view things happening in the past, but not be in the same physical space as the event, since one would need to travel away from it to catch up and pass the light - just as we can now watch the early millenia of the birth of the universe by looking at the far reaches of the universe with the Hubble telescope.
But time travel will always fail on the laws of thermodynamics - ie, you 'can't reverse a broken glass to make it unbroken'.

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...at least, not without your body coming apart at the atomic level.

I should probably add that I didn't understand a lot of the book, still working on that one. It's schrodinger's cat that fascinates me.

chris

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Hi NMott

My take on it would be different frequencies of vibration, I suppose that would mean a multi-dimensional universe.

Love the quote from Brian Cox! LOL...

Alex - after reading Prof Cox's book I gather that the speed of light is a constant, and it moves at a constant speed regardless of how fast you are going (so it's the same to all observers as you say). It moves away from you at 299,792,458 metres per second but even if you speed up to catch it, it still moves away at the same pace. Quite brain-stretching isn't it!

I found the discussion of absolute motion interesting (the fact that there can be no such thing as absolute motion as we are all moving, be it on earth around the sun, or the sun around the Milky Way etc). So how do we really calculate the speed of something? Relativity I think!

It helped me to understand these concepts if I 'slackened' my brain off and just accepted them for what they were.

Clondon - Schrodingers cat is a fascinating concept, but one that goes against our developed reasoning of the world as we know it. To have something that can be alive and dead at the same time simply baffles the mind. It gets even more weird when you think that atoms at a quantum level just appear and disappear in and out of existence.

Also, its quite interesting to note that measures of atomic particles are actually just probabilities (I think I have understood this right!). As the atoms appear and disappear you cannot actually locate them, you just give a guess of where you expect them to be.

Quantum physics is a really odd but fascinating world! I think it's the only thing I enjoy being baffled by. Then again, a new Einstein could propose something tomorrow that could make all of the above wrong!

(Disclaimer - if i've been reading the above book and haven't understood anything, but I think I have, please point out the fact that i've been a plonker!)

Hi Ben,

Your point about absolute motion is key to the question of why Einstein developed his Theory of Relativity. According to Newton's theories, there is no such thing as an absolute speed, or an absolute position. You measure speed (actually, velocity - a speed and a direction) relative to something else's velocity, and position relative to something else's position. However, when James Clerk-Maxwell developed his theory of electromagnetism, it allowed you to calculate the speed of light from fundamental constants. That seemed to imply that there was such thing as an absolute speed, namely the speed of light. Thus, Maxwell's theories appeared to contradict Newton's theories, making it appear that one of them was wrong.

It turns out they are both right, and Special Relativity is what makes this possible. The speed of light is a constant, because the laws of electromagnetism say what it must be. So everyone must measure its speed to be the same, no matter where they are, or how they are moving.

The Schrodinger's cat thought-experiment is another matter. Although I understand what it is trying to say, I don't accept the basic premise of the experiment, namely that the cat is neither alive nor dead until someone opens the box. Why? Well, because the cat is conscious of its situation, and therefore it is an observer in its own right. Substitute a person for the cat, and this fact becomes obvious. So electrons behave like that, but cats don't.

Alex