1
If, years later, I do use the slit detector to observe which way the electron went, it will mean that many years earlier the electron must have passed through one slit or the other. But if I don't use the "slit detector, " then the electron must have passed through both slits. This is, of course, extremely weird. My actions at the beginning of the twenty-first century can change what happened thousands of years ago when the electron began its journey. It seems that just as there are multiple futures, there are also multiple pasts, and my acts of observation in the present can decide what happened in the past. As much as it challenges any hope of ever really knowing the future, quantum physics asks whether I can ever really know the past. It seems that the past is also in a superposition of possibilities that crystallize only once they are observed. .Marcus Du Sautoy
2
One of the most curious consequences of quantum physics is that a particle like an electron can seemingly be in more than one place at the same time until it is observed, at which point there seems to be a random choice made about where the particle is really located. Scientists currently believe that this randomness is genuine, not just caused by a lack of information. Repeat the experiment under the same conditions and you may get a different answer each time.Marcus Du Sautoy
3
To understand this new frontier, I will have to try to master one of the most difficult and counterintuitive theories ever recorded in the annals of science: quantum physics. Listen to those who have spent their lives immersed in this world and you will have a sense of the challenge we face. After making his groundbreaking discoveries in quantum physics, Werner Heisenberg recalled, "I repeated to myself again and again the question: Can nature possibly be so absurd as it seemed to us in these atomic experiments?" Einstein declared after one discovery, "If it is correct it signifies the end of science." Schrödinger was so shocked by the implications of what he'd cooked up that he admitted, "I do not like it and I am sorry I had anything to do with it." Nevertheless, quantum physics is now one of the most powerful and well-tested pieces of science on the books. Nothing has come close to pushing it off its pedestal as one of the great scientific achievements of the last century. So there is nothing to do but to dive headfirst into this uncertain world. Feynman has some good advice for me as I embark on my quest: "I am going to tell you what nature behaves like. If you will simply admit that maybe she does behave like this, you will find her a delightful, entrancing thing. Do not keep saying to yourself, if you can possibly avoid it, 'But how can it be like that?' because you will get 'down the drain, ' into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that.Marcus Du Sautoy
4
It does appear that some parts of our evolutionary process seem inevitable. It is striking that throughout evolutionary history, the eye evolved independently fifty to a hundred times. This is strong evidence for the fact that the different rolls of the dice that have occurred across different species seem to have produced species with eyes regardless of what is going on around them. Lots of other examples illustrate how some features, if they are advantageous, seem to rise to the top of the evolutionary swamp. This is illustrated every time you see the same feature appearing more than once in different parts of the animal kingdom. Dolphins and bats, for example, use echolocation, but they evolved this trait independently at very different points on the evolutionary tree.Marcus Du Sautoy
5
If I keep observing the uranium, which means a little more than keeping my eyes on the pot on my desk and involves something akin to surrounding it with a whole system of Geiger counters, I can freeze it in such a way that it stops emitting radiation. Although Turing first suggested the idea as a theoretical construct, it turns out that it is not just mathematical fiction. Experiments in the last decade have demonstrated the real possibility of using observation to inhibit the progress of a quantum system.Marcus Du Sautoy
6
Some might question whether it makes sense to talk about setting up the experiment and running it again with exactly the same conditions--that it is, in fact, impossible. Locally, you might get the conditions exactly the same, but you have to embed the experiment in the universe, and that has moved on. You can't rewind the wave function of the universe and rerun it. The universe is a one-time-only experiment that includes us as part of its wave function, and there's no going back. .Marcus Du Sautoy
7
For any scientist the real challenge is not to stay within the secure garden of the known but to venture out into the wilds of the unknown.Marcus Du Sautoy
8
I think science is a foreign land for many people, so I think of my role as an ambassador's job.Marcus Du Sautoy
9
When people ask me what my religion is, I say it's the Arsenal.Marcus Du Sautoy
10
Mathematics has beauty and romance. It's not a boring place to be, the mathematical world. It's an extraordinary place; it's worth spending time there.Marcus Du Sautoy
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The power of mathematics is often to change one thing into another, to change geometry into language.Marcus Du Sautoy
12
The reason why we do maths is because it's like poetry. It's about patterns, and that really turned me on. It made me feel that maths was in tune with the other things I liked doing.Marcus Du Sautoy