EncycloZine

Why is there Something instead of Nothing? This question has fascinated me for almost as long as I can remember. I rejected theosophical explanations at an early age, since essentially all they did was to ascribe existence to a supernatural being, whose own existence was beyond rationality and questions. No, the answer should at least attempt to be scientific, that is, open to the methods of science such as experiment and falsification.

Quantum theory has come the closest to offering at least a partial answer, in the Big Bang theory. We suppose that there was a quantum fluctuation according to Heisenberg's Uncertainty Principle, in some pre-existing space-time, which then 'inflated' much faster than the speed of light (thus ironing out inhomegeneities) before settling down to a much slower rate of expansion, as observed today.

This of course, still leaves open the question of where the underlying 'implementation fabric' and physical laws came from. At this point the question becomes more metaphysical and philosophical, looking for an intuition as to how to bootstrap existence into being. As soon as you have an idea where physical laws came from, e.g. mathematics, you have to explain that (some people are attempting to create self-creating mathematical models).

The there's the question as to why there should be a Universe in which such complex things such as concious beings can exist. First, the Universe apparently is very fine-tuned, such that had some physical constants been only slightly different, life could not exist. Then there's the puzzle as to how life itself managed to swim against the current of entropy, i.e. disorder - the 'natural' tendency of things to become randomly ordered. How tempting it is to just give up and invoke a Designer!

However, we are strongly influenced by the fact that we perceive only one Universe. Our outlook would be fundamentally different if we knew that there were an infinite number of other universes; 'most' of them might indeed be meaningless in terms of order and conciousness, but in an infinity of varying physical/mathematical schemes, there have to be some (in fact, an infinity) of universes having just the right ingredients and structure to support conscious beings.

One interpretation of Quantum Mechanics does indeed state that there exist 'many worlds' (aka a multiverse), generally named after Hugh Everett III who proposed it. It serves to explain what happens to the 'wave function' of a physical system, when it is 'observed'. Classically this wave function, which describes the probability distribution of all possible states of the system, 'collapses' to leave only the state specifically observed. But according to Everett, what actually happens is that all those other possible states branch off into their own universes...

The major counter-argument to this is that it violates a 'principle' of science known as Ockham's Razor - a strong preference for simpler explanations instead of complex ones. Some find a continually branching out of an infinity of universes from every observable event, to be a preposterous violation of this principle. I don't subscribe to this view. First, Ockham's Razor isn't a Law of science. It has no theoretical foundation. Second, I don't agree that many-worlds violates it; I find it much simpler to allow reality to branch without constraint, than to have to postulate all the physical laws that characterise our Universe.

MWI is philosophically very satisfying, and may even be open to experimental verification. So, one possible answer to the 'something instead of nothing' question may be that 'nothing' is unstable - it has no laws constraining reality - and so 'everything' exists, just as every possible statue exists inside a block of stone. Unconstrained existence contains every logically possible universe, and we just inhabit one of them. Perhaps one day we'll find evidence for some of the others. Some say that quantum computers will be unimaginably faster than classical computers, by virtue of performing calculations in some of those parallel universes...

A Computer Scientist's View of Life, the Universe, and Everything

Is the universe computable? If so, it may be much cheaper in terms of information requirements to compute all computable universes instead of just ours. I apply basic concepts of Kolmogorov complexity theory to the set of possible universes, and chat about perceived and true randomness, life, generalization, and learning in a given universe.

Many Worlds

The basic idea here is that there are many worlds that exist, each potentially with different physical conditions. (The special case of mini-universes, defined here as conscious instants of experience, will be dealt with elsewhere.) Most such worlds are likely to be unfavourable to life, but we are of course in one of the few that are not. This hypothesis is often put forward when attempting to circumvent the fine-tuning problem posed by the Anthropic Principle: the apparent coincidence of the physical laws and their constants being closely compatible with the requirements of life as we know it is explained by the multiplicity of worlds with different physical laws.

THE EVERETT FAQ

This FAQ shows how quantum paradoxes are resolved by the "many-worlds" interpretation or metatheory of quantum mechanics. This FAQ does not seek to prove that the many-worlds interpretation is the "correct" quantum metatheory, merely to correct some of the common errors and misinformation on the subject floating around.

The Many-Worlds Interpretation of Quantum Mechanics

The Many-Worlds Interpretation (MWI) is an approach to quantum mechanics according to which, in addition to the world we are aware of, there are many other similar worlds which exist in parallel at the same space and time. The existence of the other worlds makes it possible to remove randomness and action at a distance from quantum theory and thus from all physics.

MWI is philosophically very satisfying, and may even be open to experimental verification. So, one possible answer to the 'something instead of nothing' question may be that 'nothing' is unstable - it has no laws constraining reality - and so 'everything' exists, just as every possible statue exists inside a block of stone. Unconstrained existence contains every logically possible universe, and we just inhabit one of them. Perhaps one day we'll find evidence for some of the others. Some say that quantum computers will be unimaginably faster than classical computers, by virtue of performing calculations in some of those parallel universes...

A quantum leap in computing

May 18 — The world of quantum mechanics goes against the grain of everyday experience. It’s an “Alice in Wonderland” realm beyond the ones and zeroes of classical computing. But if we can figure out how to put this world to work, it would lead to a technological quantum leap, allowing us to solve problems that would take millions of years to figure out using present-day computers. And that has huge implications for the Internet — indeed, for any means of communicating data.

Centre for Quantum Computation

The discovery that quantum physics allows fundamentally new modes of information processing has required the existing theories of computation, information and cryptography to be superseded by their quantum generalisations. The Centre for Quantum Computation, part of the University of Oxford, conducts theoretical and experimental research into all aspects of quantum information processing, and into the implications of the quantum theory of computation for physics itself.

What is Quantum Information Processing?

It was observed already in the 1960s by Rolf Landauer, that information is physical, i.e. information cannot be separated from its physical representation: it is always stored in some physical system, manipulated by some physical process. This observation has a number of consequences for information theory. Perhaps, the most striking one is, that it makes a big difference whether the information is stored and processed in classical or quantum mechanical systems.

QUANTUM COMPUTING

How the weird logic of the subatomic world could make it possible for machines to calculate millions of times faster than they do today

Quantum computing FAQ

Last updated: 1998-06-29 Here is some stuff that's tangentially related to Quantum Computing. Just something I (David Cary) threw together that I thought you might find interesting. If you find any more related resources, I would appreciate you telling me about them so I can add (links to) them to this page.

Basic Concepts in Quantum Information Theory

Quantum Information is whatever can be transmitted by using systems obeying Quantum Theory as carriers. It is thus not any newly discovered "stuff", but has been implicit in Quantum Theory all along. In fact, some approaches to the foundations of quantum theory (e.g., Ludwig's from the 60ies [Lu83]) are based on the view that Quantum Theory is precisely about the kind of influence transported from a preparing device (the "transmitter") to a measuring device (the "receiver"). What is new in the recent work on quantum information theory is that this view is taken seriously in a quantitative way. The basic questions of this theory are taken from classical information theory: how much "quantum information" is carried by any given system or transmission channel, how much is stored in a storage device, how can such information be coded and decoded efficiently etc.

The Qubyte Forum:

Quantum Computers & Moore's Law This site is dedicated to tracking whether or not the increase in power or complexity of quantum computers will follow the same trend as silicon based classical computers. For classical computers this trend is defined by the famous "Moore's Law" which states that the number of transistors in computer chips will double every eighteen months. An analogous trend for quantum computers would be that the number of qubits will double every eighteen months (or perhaps some other regular time period). There is not yet enough data to determine a trend for quantum computers, but the few points available are provided on the graph below.

IBM Almaden

In the words of Niels Bohr,"Anyone who is not shocked by quantum theory has not understood it!" Shocking indeed to find that quantum bits, or qubits, can be both 1 and 0 at the same time! Or that it can be impossible to eavesdrop on a message sent as qubits! Our scientists are exploiting such quantum weirdness to build quantum logic gates as a step towards a super-powerful quantum computer. In other work they are inventing ultra-secure crytography systems in which data is coded in the quantum states of individual photons.

Subatomic Logic

The subatomic world, where particles are not solid objects so much as smears of probability, may seem counterintuitive, even illogical. But since the early 1980s, a number of scientists (starting with the late Richard Feynman) have been thinking through schemes to exploit the oddball laws of quantum physics to rational ends; their goal is to create a radically new kind of computer, one far smaller and swifter than any modern silicon device. Though a functional "quantum computer" still lies beyond the grasp of current technology, a succession of theoretical and practical advances suggests some heartening progress toward that goal.

Quantum Computing with Molecules

Factoring a number with 400 digits--a numerical feat needed to break some security codes--would take even the fastest supercomputer in existence billions of years. But a newly conceived type of computer, one that exploits quantum-mechanical interactions, might complete the task in a year or so, thereby defeating many of the most sophisticated encryption schemes in use. Sensitive data are safe for the time being, because no one has been able to build a practical quantum computer. But researchers have now demonstrated the feasibility of this approach. Such a computer would look nothing like the machine that sits on your desk; surprisingly, it might resemble the cup of coffee at its side.

dmoz: Computers: Computer Science: Theoretical: Quantum Computing