Some of the recent coverage regarding how poorly we are doing as a society, as teachers, as parents, and certainly as students with regard to history and geography has led me further afield. For those who consider themselves to have sufficient acumen in history and geography…there are far longer and bigger frames of reference to consider.
There is much which is an outgrowth (or merely a representative part of) cosmology and quantum physics that we all need to know more about these days. With the advent of quantum computing on the horizon, there should be deeper coverage of the underlying technology and science than (I already expect to see this…) confusing anecdotes about Schrodinger’s cat…
The amazing thing I see in our world is that few people seem to realize that with the explosion of information available to anyone with online access…there is a commensurate need for more of this information. In essence, we all need more knowledge and data, just to make it through our lives.
With this in mind, here are a couple links which may get you started into some of the biggest picture topics in the sciences…
Multiverse = Many Worlds, Say Physicists
http://www.technologyreview.com/blog/arxiv/26787
The many worlds interpretation of quantum mechanics is the idea that all possible alternate histories of the universe actually exist. At every point in time, the universe splits into a multitude of existences in which every possible outcome of each quantum process actually happens.
So in this universe you are sitting in front of your computer reading this story, in another you are reading a different story, in yet another you are about to be run over by a truck. In many, you don’t exist at all.
This implies that there are an infinite number of universes, or at least a very large number of them.
That’s weird but it is a small price to pay, say quantum physicists, for the sanity the many worlds interpretation brings to the otherwise crazy notion of quantum mechanics. The reason many physicists love the many worlds idea is that it explains away all the strange paradoxes of quantum mechanics.
For example, the paradox of Schrodinger’s cat–trapped in a box in which a quantum process may or may not have killed it– is that an observer can only tell whether the cat is alive or dead by opening the box.
But before this, the quantum process that may or may not kill it is in a superposition of states, so the cat must be in a superposition too: both alive and dead at the same time.
That’s clearly bizarre but in the many worlds interpretation, the paradox disappears: the cat dies in one universe and lives in another.
Let’s put the many world interpretation aside for a moment and look at another strange idea in modern physics. This is the idea that our universe was born along with a large, possibly infinite, number of other universes. So our cosmos is just one tiny corner of a much larger Multiverse.
Today, Leonard Susskind at Stanford University in Palo Alto and Raphael Bousso at the University of California, Berkeley, put forward the idea that the Multiverse and the many worlds interpretation of quantum mechanics are formally equivalent.
But there is a caveat. The equivalence only holds if both quantum mechanics and the Multiverse take special forms.
Let’s take quantum mechanics first. Susskind and Bousso propose that it is possible to verify the predictions of quantum mechanics exactly.
At one time, such an idea would have been heresy. But in theory, it could be done if an observer could perform an infinite number of experiments and observe the outcome of them all.
But that’s impossible, right? Nobody can do an infinite number of experiments. Relativity places an important practical limit on this because some experiments would fall outside the causal horizon of others. And that would mean that they couldn’t all be observed.
But Susskind and Bousso say there is a special formulation of the universe in which this is possible. This is known as the supersymmetric Multiverse with vanishing cosmological constant.
If the universe takes this form, then it is possible to carry out an infinite number of experiments within the causal horizon of each other.
Now here’s the key point: this is exactly what happens in the many worlds interpretation. At each instant in time, an infinite (or very large) number of experiments take place within the causal horizon of each other. As observers, we are capable of seeing the outcome of any of these experiments but we actually follow only one.
Bousso and Susskind argue that since the many worlds interpretation is possible only in their supersymmetric Multiverse, they must be equivalent. “We argue that the global Multiverse is a representation of the many-worlds in a single geometry,” they say.
They call this new idea the Multiverse interpretation of quantum mechanics.
Are Many Worlds and the Multiverse the Same Idea?
http://blogs.discovermagazine.com/cosmicvariance/2011/05/26/are-many-worlds-and-the-multiverse-the-same-idea
When physicists are asked about “parallel worlds” or ideas along those lines, they have to be careful to distinguish among different interpretations of that idea. There is the “Multiverse” of inflationary cosmology, the “many worlds,” or “branches of the wave function” of quantum mechanics, and “parallel branes” of string theory. Increasingly, however, people are wondering whether the first two concepts might actually represent the same underlying idea. (I think the branes are still a truly distinct notion.)
At first blush it seems crazy — or at least that was my own initial reaction. When cosmologists talk about “the Multiverse,” it’s a slightly poetic term. We really just mean different regions of space-time, far away so that we can’t observe them, but nevertheless still part of what one might reasonably want to call “the universe.” In inflationary cosmology, however, these different regions can be relatively self-contained — “pocket universes,” as Alan Guth calls them. When you combine this with string theory, the emergent local laws of physics in the different pocket universes can be very different; they can have different particles, different forces, even different numbers of dimensions. So there is a good reason to think about them as separate universes, even if they’re all part of the same underlying space-time.
The situation in quantum mechanics is superficially entirely different. Think of Schrödinger’s Cat. Quantum mechanics describes reality in terms of wave functions, which assign numbers (amplitudes) to all the various possibilities of what we can see when we make an observation. The cat is neither alive nor dead; it is in a superposition of alive + dead. At least, until we observe it. In the simplistic Copenhagen interpretation, at the moment of observation the wave function “collapses” onto one actual possibility. We see either an alive cat or a dead cat; the other possibility has simply ceased to exist. In the Many Worlds or Everett interpretation, both possibilities continue to exist, but “we” (the macroscopic observers) are split into two, one that observes a live cat, and one that observes a dead one. There are now two of us, both equally real, never to come back into contact.
These two ideas sound utterly different. In the cosmological Multiverse, the other universes are simply far away; in quantum mechanics, they’re right here, but in different possibility spaces (i.e. different parts of Hilbert space, if you want to get technical). But some physicists have been musing for a while that they might actually be the same, and now there are a couple of new papers by brave thinkers from the Bay Area that make this idea explicit.
Physical Theories, Eternal Inflation, and Quantum Universe, Yasunori Nomura
The Multiverse Interpretation of Quantum Mechanics, Raphael Bousso, and Leonard Susskind
Related ideas have been discussed recently under the rubric of “how to do quantum mechanics in an infinitely big universe”; see papers by Don Page and another by Anthony Aguirre, David Layzer, and Max Tegmark. But these two new ones go explicitly for the “Multiverse = many-worlds” theme.
After reading these papers I’ve gone from a confused skeptic to a tentative believer. This happened for a very common reason: I realized that these ideas fit very well with other ideas I’ve been thinking about myself! So I’m going to try to explain a bit about what is going on. However, for better or for worse, my interpretation of these papers is strongly colored by my own ideas. So I’m going to explain what I think has a chance of being true; I believe it’s pretty close to what is being proposed in these papers, but don’t hold the authors responsible for anything silly that I end up saying.
