Parallel universes theory by David Deutsch-- Newscientist

[Swede]

http://www.newscientist.com/hottopics/quantum/quantum.jsp?id=22994400

"One day, a quantum computer will be built which does more simultaneous calculations than there are particles in the Universe," says Deutsch. "Since the Universe as we see it lacks the computational resources to do the calculations, where are they being done?" It can only be in other universes, he says. "Quantum computers share information with huge numbers of versions of themselves throughout the multiverse."

This stuff fascinates me.

[Wilber_Stool]

1. Have you read

"Time Line" by Michael Crichton. It involves time travel with a quantum multi-verse slant. Time travel is not possible in this universe, so you build a machine to travel to a universe where it is.

[Ready4Change]

2. I assume

That Duetsch is assuming that Moores law will continue forever. Moores law stats that computers will doubling in power every (2?) years, which thus far has proved a conservative estimate.

However, I think that asusmption is false. It's kind of like saying "If I save 1 dollar today, then 2 tomorrow, 4 the next, then 8... ' doubling the amount saved, then I'd be a millionaire in a month.

But fun to take even further. Since every particle in our universe is affected, even minutely, by every other particle, then each particle needs the services of it's own universe in order to be accurately simulated. However, since their can be an infinite number of parallel universes, this isn't really a limitation.

[Wilber_Stool]

3. Actually,

you would only have to start out with one penney to end up a multi millionaire at the end of the month.

[Bernardo de La Paz]

4. Quantum does not depend on Moore's Law

The interesting thing about quantum computing is that it does not depend on Moore's Law. The way it works is that if you have 10 quantum thing-a-ma-bobs going (quantum bits or qubits), then you can calculate the one in 2 raised to the 10th power result: one in 1024. Thus theoretically, if the universe has 10 raised to the 92nd power particles (10 followed by 92 zeros), you could compute their state with six degrees of freedom to 3 digits precision with about 360 qubits.

Needless to say, I have a very fuzzy understanding of only the most basic concepts involved, and also there will have to be much development before we can even think of 10 qubit computers as practical devices. But it could easily happen sooner than most of us think.

[Ready4Change]

6. Is there a means of quickly manipulating qubits?

I'm not REAL up on this. Qubit=one quantum bit?

I think I've read that they'd managed to manipulate qubits to store info. But I don't have any idea how quickly they've actually done it, nor how much equipment is needed. Any information on that?

[Bernardo de La Paz]

8. Think Schrodinger's Cat

Basically it works by setting up the qubits in an indeterminate state until they are actually examined whereupon they settle into the correct state for the computed result. Like Schrodinger's Cat metaphor (why couldn't it have been a rat?) where the state of the cat being alive or dead as a result of a particle interaction with the poison is not known until the box is opened.

Addendum: found explanation: http://www.newscientist.com/hottopics/quantum/parallel.jsp

[Ready4Change]

9. Interesting website, btw.

I'll have to look it over when I have more coffee in me. :) I have read the two pages linked in this thread, though.

I kind of get how these are supposed to work in theory. But, being a programmer of current computers, I'm still uneasy about how to get reliable results from these "qu-mputers." (Maybe I should trademark that term. :) )

What I'm wondering is what the current state of the art is. I've heard labs have done this with pairs or even 4 qubits, but I haven't heard how much equipment, nor how much time, the process takes.

Also, because of the unreliability of quantum results when measured it seems to me that it will be very difficult to "program" such a computer to produce a usable result. You might wind up with computer with an incredibly deep processing ability, but which is practically impossible to program for a reliable result.

In other words, a theoretically great thing, but practically useless.

[brokensymmetry]

5. Neat article! n/t

.

[Dogmudgeon]

7. David Deutsch had better watch it with that talk

CSICOP (et al.) does not approve of such ideas.

"One day, a quantum computer will be built which does more simultaneous calculations than there are particles in the Universe" ... ? That's what Frank Tipler once said. And we all know about woo-woos like Frank Tipler.

The next thing you know, Deutsch will be fondling his crystals, reading the Voynich Manuscript, and claiming that psychology is a science. And from there, it's just a short hop down the slippery slope to the barbarian hordes laying siege to our universities, breaking men of science on the wheel, smashing the machines of industry, and worshipping space cooties!

Well, maybe not in this universe ...

--bkl
They all laughed at Dennis Miller. But they were wrong.

[Swede]

10. The Turing Machine says calculations of intetdimensional space

Quantum computers also utilize another aspect of quantum mechanics known as entanglement. One problem with the idea of quantum computers is that if you try to look at the subatomic particles, you could bump them, and thereby change their value. But in quantum physics, if you apply an outside force to two atoms, it can cause them to become entangled, and the second atom can take on the properties of the first atom. So if left alone, an atom will spin in all directions; but the instant it is disturbed it chooses one spin, or one value; and at the same time, the second entangled atom will choose an opposite spin, or value.

http://computer.howstuffworks.com/quantum-computer1.htm

[Swede]

11. "We cannot go forward or backward in time,nor sideways."

But why can't we look?