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Comment from James Cates
Date: August 12, 2008, 12:06 pm

The prospect that we do not have free-will is absurd to me. Surely, there are multiple possibilities in any given situation. Brian never explains why “I” in one “place” does not choose option A while in another “place” “I” choose B.

I find it totally absurd to suggest that free-will is just a useful, comforting and necessary component that helps us get through the day. In that case, has Brian suddenly discovered the Red pill? In that case, he is more or less also suggesting that everything is pre-defined according to some cosmic formula which leads to a pretty divine suggestion.

Brian, do you realize how creationist your idea is? You are handing over all creation and logic to a single, unknown entity.

So, you maybe you are exposing the matrix and its maker(s), eh?

You realize, of course, that it is sort of pointless for you to TRY to discover any of this since you are by your own suggestion pre-disposed to do so and can’t do a thing to change that. (grin) Really?

Comment from James Cates
Date: August 12, 2008, 12:11 pm

Have you ever had the feeling that you just avoided something disastrous?

Maybe in one reality I choose A and cause mayhem, while in another I choose B and things turn out better and closer to “the script”.

Maybe we do have free-will with the realm of each reality, each choice and outcome is weighed and the one closest to “the script” is made the central reality. Maybe there are these multiple realities between which we can instantly shift and we are constantly being swapped around by a controller algorithm as described…

Why is THAT not a possibility? Brian, I find your particular solution to be extremely pessimistic and limited.

Comment from Katrin
Date: August 12, 2008, 5:26 pm

Freewill is given to mankind to make mistakes and learn from them. Life is a long journey of learning. Don’t even get me started on reincarnation and karma. Peace

Comment from Dave Kliman
Date: August 13, 2008, 2:14 am

I have to disagree with Dr. Greene on the idea that just because there may be infinite space for finite configurations of atoms, who is to say imelda marcos will EVER wear those red shoes in the corner?

what is to say each and every possibility MUST play out?

I have been exploring the mandelbrot fractal for years. there are an infinite number of possible images in there, but i just do not think one will ever be able to find the equivalent of every photo ever taken.

the same applies to things like kotch snowflakes. you can have i suppose what amounts to a finite number of possible kotch snowflakes, but there will never be one that looks like the script for hamlet. ever.

Does Dr. Greene have some kind of proof that every single possibility MUST play out?

Comment from alexandre van de sande
Date: August 13, 2008, 11:16 am

I believe Brian Greene contradicts himself when he tell us that modern science has disproved the “clockwork” universe newton described but then Brian describe a very “clockwork-like” bird when he states that we could in theory know where the live bird in a canon would fall.

He is certainly wrong, probably because he is letting his personal relaxed opinion on free-will contaminate a very scientific talk.

The error consist in the idea that one could possibly know everything about a bird so to be able to know where it would land after shot by a cannon. We physically can’t.

First, the Heisenberg Uncertainty Principle he himself states makes it clear that we can at best determine the chance of a certain eletron in the brain of the bird being in a certain place. When taken in account every atom that makes up the bird that uncertainity scales up very quickly.

Secondly the study of chaos theory also shows that those small bits of uncertainity can result in radically different and unpredictable results.

Therefore according to modern, non-newtonian physics, the best a modern physics expert could tell you is that given a live bird is shot in the air there’s a high probability he will die of heart attack, but there’s also a chance he will fly the hell away from those crazy scientists and land in a far away tree where there is some shade.

Comment from Matt
Date: August 13, 2008, 11:27 am

Does this mean that somewhere in the universe movie-physics might apply? People can jump out of the way of explosions, bullets ricochet until they hit their intended targets, and cars are indestructible?

More seriously, how far ahead of engineering is this science? In other words, how long (if ever) until there is application of these theories to human life? Is it already happening and, if so, in what fields? Communications? Computing? Energy?

I had little patience for similar conversations about the other spectrum of modern physics (atomic science) until I met an electrical engineer taking advantage of electron spin in his circuit designs. Impressive. Humbling.

Comment from Lola Rogers
Date: August 13, 2008, 11:54 am

I keep going round and round about the probability thing, and I end up with the same question Dave Kilman asks above: the fact that something can happen doesn’t mean it will.

The idea in your discussion is that, given enough time and space, infinite time and space, everything that can happen will happen. But is that how probability really works?

What about the gambler who sits at the roulette table for hours and hours, calculating that if he sits there long enough, probability dictates that he will eventually win. The problem is that he’s no more likely to win the millionth time the wheel goes around than he was the first time.

Can anybody point out what I’m missing here?

Comment from Dave Lockwood
Date: August 13, 2008, 2:09 pm

The elephant in the room is the whole idea of calling the universe infinite. If you take that one concept out of the argument the irrational aspects go up in a puff of logic. Perhaps, despite scientists’ assumptions, the universe is not infinite and what we have is reality expanding into nothing. In other words, reality and the laws of physics are generated as we go along. Since that is what we observe that must be the case. As soon as we observe something different let me know and I’ll reconsider.
I have the utmost respect for Dr. Greene and feel this was a setup. Without a firm grasp of the concept of infinity this all sounds like nonsense. This looks to be to be hatchet job by the interviewer who constantly played to the incredulity of the audience at the expense of Dr. Greene.

Comment from Alex Grigg
Date: August 13, 2008, 2:37 pm

From Dave Kliman “what is to say each and every possibility MUST play out?”

There is less to say that every possibility MUST play out, although if we assume an infinite universe with infinite variations of the laws of physics it does seem likely. The fact that something does happen once, though, suggests that it is possible and therefor in an infinite universe where many worlds are similar to our own some of them will be exactly the same. If your “infinity” is big enough then there will be infinite worlds where exactly the same thing happens.

alexandre van de sande says there is a contradiction between a clockwork, no free will, universe and the universe of infinite variations.

The water does get a little muddy here and I don’t think Brian had sufficient time to adequately explain the no free will theory. Quantum physics and uncertainty principles are hard enough to understand that I don’t think I can explain the lack of contradiction, especially since I’m not sure I have a firm grasp on them in the first place. What is important, though, is that physics cannot explain free will. You can say the position of an electron is as uncertain as you like, but we don’t choose where that electron is and what it’s speed is, or whatever the actual particles are that we’re unable to exactly describe.

Comment from Rob Palmer
Date: August 13, 2008, 5:45 pm

Fortunately, Heisenberg does not scale up. In the classical realm I can know both an object’s position and momentum with sufficient precision for predictability.

Or, perhaps better put, the uncertainty of classical objects is so tiny as to be negligible. The fuzziness of cannonballs does not diminish their effectiveness.

It is usually not productive to question scientists’ calculations. The mathematics are generally widely agreed. Their assumptions and interpretations are fair game however. I don’t think there is much question that dividing infinity by a finite number will offer endless repetitions.

One approach, to question whether infinity is an appropriate description of the multiverse is certainly valid and has been mentioned previously.

But there is another way to question the assumptions of this particular multiverse theory. In the calculations particles are described as space-like objects (a finite calculation) divided into a multiverse of infinite space and presumably infinite time.

If we are to take Einstein seriously, we have done some significant damage to our conceptualization of particles by stripping out their time-like qualities. Welding time-like qualities back into our calculations of the particles yields a very different result.

In order to achieve a finite number that can be divided into an infinite multiverse we must arbitrarily limit time in some way. If the particles in our universe have an infinite time-like quality then we actually dividing an infinite number into the infinite multiverse and the result is that the multiverse is under no obligation to repeat itself.

Comment from Rob Palmer
Date: August 13, 2008, 6:21 pm

If the particles in our universe have an infinite time-like quality then we [are] actually dividing an infinite number into the infinite multiverse and the result is that the multiverse is under no obligation to repeat itself.

Comment from Amanda Black
Date: August 14, 2008, 11:19 am

Did any Lost fans find familiar themes here? I sure did!

Comment from Dibs
Date: August 14, 2008, 1:31 pm

Free will/no free will, I think most of the posters completely missed the point. It is not the job of science to explain the “why” of things but the “how.” Dr. Greene is simply explaining the mathematical model of how things could work given the information that we have today. What is wonderful about science and Dr. Greene mentions this several times, that if something new is found, science is more than happy to revise itself to fit the new data. There are still plenty of unanswered questions that people can fit into the notions of free will if they find that comforting. We don’t know why the ‘energy field’ the ‘cheese’ in the story folds down in such a way to create our bubble universe and not another type, etc etc etc. We don’t know why the you that is you is in this area of the universe and not in another area, all that stuff still adds up to some wonderful mysteries out there.

Comment from Rob Palmer
Date: August 14, 2008, 3:52 pm

There are various approaches to free will. Greene believes in the block universe/multiverse implied by Einstein.

http://www.wnyc.org/shows/radiolab/episodes/2005/03/04/segments/44571

That is not a position that ’science’ has settled on but rather an interpretation to which some scientists adhere. It is based on the ideas of causality and determinism. If your actions are perfectly determined in advance, then free will is an illusion much as Greene claims. If your actions are only probabilistically determined then there is still some wiggle room for free will. (At least this version of it, leaving aside Ramachandran’s post hoc rationalization.)

It all basically comes down to how you interpret Heisenberg. A strong interpretation is that knowing a quantum object’s position makes its momentum indeterminate and leads to a conclusion that the future is open ended. A weak interpretation sees this phenomenon as merely a product of measurement, that the momentum is still determined but we cannot discover what it is. That position postulates that there are hidden variables at work that we have yet to find which would allow for an absolutely determined universe in which free will is an illusion.

Myself, I think hidden variable theories are tremendously hopeful. The Everettian many-worlds interpretation is one such theory but postulates a different version of the many worlds than is discussed in this thread. In the Everett MWI the other worlds are not spatially distant as we have been discussing but produced so that every possibility is actualized. So there really is a world in which I chose chocolate rather than vanilla.

The problem is that Heisenberg is not going to go away. MWI or even Bohmian QM may try to explain it ontologically, but they are not going to get around it: Uncertainty has been experimentally demonstrated to great precision.

And while the absolute determinists make bold promises about being able to perfectly predict the flight of a bird in the golden future, probabilistic determinists such as Iain Couzin are producing stunningly accurate models of entire flocks of birds in the here and now.

http://www.princeton.edu/~icouzin/Current%20research.htm

The elephant in the room is actually time itself. We don’t really have a handle on it. Even as we do accept that space and time are unified, spacetime, our metaphysics is entirely constructed on the basis that space is one thing and time is another.

Comment from Ken Luallen
Date: August 14, 2008, 4:30 pm

First I am a bit surprised by the vehement reactions to Brian Greene’s belief that there really isn’t any free will. His theories are perfectly logical and quite well-articulated. Why can’t you respect that? If you truly believe in free will (as I do) someone’s reasonable alternate belief should not bother you. I am quite glad Brian and Robert were able to discuss and challenge his ideas without any hint of hostility or sarcasm. Taking the high road serves all sides of a debate.

The problem with any infinity-based theory is that it scales infinitely and only grows less conclusive and less indicative of anything. This is the great irony with scientists — the ever-expanding scope of a world defined by physics constantly suggests that all existence simply must be created and ordered by something that does not obey the laws of physics.

That said, physics and God are not in conflict at all, they exist on completely different levels. I am amazed that some scientists are willing to extend their minds through the extraordinary distances of infinity but so deeply unwilling to go a step further into what must be beyond infinity.

I always appreciate the fact that Robert very subtly poses this dilemma in every interview. (His subjects duck it every time.)

Great job once again.

Comment from eric
Date: August 14, 2008, 5:31 pm

In order from things to repeat themselves, doesn’t there need to be multiple closed systems (universes)with the same particles in each system (universe) for this to work? In one universe isn’t every particle having an effect on every other particle?

Comment from eric
Date: August 14, 2008, 5:36 pm

One more comment, sorry . . . I don’t believe that because 23 other people decided to go to Pineapple Express last Monday night, that none of had free will.

Comment from Rob Palmer
Date: August 14, 2008, 6:04 pm

Ken Luallen:

I guess I’ll take the low road.

I see nothing in physics that suggests existence must be created and ordered by something that does not obey the laws of physics much less am I constantly confronted by such.

The phrase ‘beyond infinity’ sure sounds nice. But it is void of actual content. Definitionally, it is about as sensible as the playground invective of infinity plus one.

Perhaps you could demonstrate specifically your justification for these conclusions. Specifically what are these constant dead giveaways of God’s existence? On what basis have you dismissed all infinity based theories?

Many mathematical theories are infinity based. Perhaps you can show me how math suffers from this and becomes less conclusive or indicative of anything.

Comment from RadCap
Date: August 14, 2008, 7:28 pm

When ideas are divorced from facts - when they are accepted arbitrarily - fantasy is the result. Whether the person who does this calls himself a professor or a voodoo priest doesn’t change the fact that their ideas are pure non-sense (literally).

Rationalism (in its ’secular’ or religious form) is an intellectual dead-end.

Comment from Marcus
Date: August 14, 2008, 7:44 pm

Just like monkeys writing Hamlet.

If Brian Greene is right, I guess there are lots of Hamlets, lots of Shakespeares and lots and lots and lots of monkeys.

Who knows if it’s true, but it’s fun to think about so many monkeys.

I’m surprised by the comments that dismiss what is essentially an easy argument. Finite possible arrangments distributed over infinite space (two big assumptions), lead to inevitable duplication.

And more monkeys.

Comment from Jimmy
Date: August 15, 2008, 12:49 am

I think some people here are missing the point; alternative universes mean that everything has happened. Because anything can be traced back to a single point, albeit sometimes way back. By definition, alternative universes dictates that you have already developed the cure for cancer in the bathroom, while simultaneously inventing the flux capacitor and destroying exactly 58/42th of the universe in exactly 8.9352+(5/pi)^7 seconds, infinite times.

Comment from Ren
Date: August 15, 2008, 8:59 am

Wait! Wait! Wait!

What?

Comment from Nilesh
Date: August 15, 2008, 9:33 am

As discussed in the podcast, if I start travelling in one direction…. and keep travelling… and travelling… until I reach a parallel universe, why would I find another me? Wouldn’t THAT another me be travelling and reaching another parallel universe at the same time? Since the other me will make the same thoughts and actions at the same time as me?

Comment from Nathan
Date: August 15, 2008, 2:10 pm

@ Dave Kliman

Given infinity, there is no proof required, as eventually everything will repeat as there only a finite, though exceedingly large, number of possibilities so long as there remains a finite number of particles.

Comment from Clever Human
Date: August 15, 2008, 4:07 pm

There seems to be a flaw here.

At the beginning of the podcast an analogy was used about flipping coins. It stated that with an infinite number of flips, even the most unlikely combination would occur — 1,000 heads in a row was the example used.

But there are some examples that would never show up in an infinite number of flips — all heads or all tails. Because if those two showed up, then none of the other really unlikely chances would happen (you can’t have 1,000 heads in a row if you are flipping all tails.)

And then the rest of the podcast goes on to talk about infinite heads showing up (if the analogy is that heads is an exact duplicate of an atom in this universe, and tales is a difference in that atom).

The one combination that cannot show up again is the one that leads to exact duplication of everything.

Does this make sense, or am I missing something.

I know analogies != physics.

Comment from Matt
Date: August 15, 2008, 4:42 pm

Ridiculous. Math is a tool to represent reality, not the other way around. Physicists live so much in the world of math they think the rest of the world has to conform to math rather than make math conform tot he rest of the world. Silly kitties!

Still, there is value in running around and talking this kind of thing up. It helps get grant money. Study particles dancing around? *yawn* Study Kewl Froopy Multiverses?? Wow, let’s pay for that! Amazing how easy it is to dupe even the top 1% of society into scarfing up such nonsense.

Comment from Audita Sum
Date: August 15, 2008, 5:06 pm

When I read a booklet on parallel universes by Scientific American, I thought it was totally stupid. Mostly because if one takes any of the quantum theory examples– flipping a coin or rolling a die, for instance, there is no real chance. That coin is ‘fated’ to land on a certain side or that die is ‘fated’ to land on a certain number because of the way you threw it, the surfaces surrounding it, etcetera. The way you threw it has its own subconscious reasons too, and isn’t the result of some probability. In my mind, probability is just our guessing and ascribing percent symbols.

Listening to this podcast, though, I found myself being pulled in. If atom arrangement really is random and has no actual causes, then sure. Maybe quantum theory is a possibility. And then, maybe multiple universes are a possibility.

Still, I don’t see why we have to complicate it to multiple universes. Can’t we just have one universe, with an infinite number of Earth-duplicates floating around in it? How can equations lead to the knowledge that our universe could be a bubble within a bubble? Seriously. I’d like to know this stuff.

Comment from Audita Sum
Date: August 15, 2008, 5:08 pm

And I haven’t believed in free will for quite some time. Hee hee.

Because, you know, I’m the sum of my atoms.

Comment from Rob Palmer
Date: August 15, 2008, 11:47 pm

There are different classes of many-world ideas. The versions that Brian Greene is discussing doesn’t necessarily have anything to do with quantum mechanics. If you are keen, Max Tegmark lays out the many worlds landscape in an academic lecture:

http://pirsa.org/07090063/

As to quantum mechanics, there is simply no question about it. It has been experimentally confirmed to a far greater precision than perhaps any other mode of knowledge.

It is, however, extremely difficult to explain using classical terms. If you really want to understand, the math is unavoidable. Leonard Susskind offers a free online course that can be followed using high school level math:

http://www.learnoutloud.com/Catalog/Science/Physics/Modern-Theoretical-Physics/23022

So anyone trying to explain QM using classical objects such as dice or coins is drawing an analogy that is necessarily flawed.

The most straightforward method of explanation I know of is the double-slit experiment:

http://en.wikipedia.org/wiki/Double-slit_experiment

Essentially, classical statistical mechanics sensibly predicts that the probability of quantum particles passing through two slits should be the sum of the probability of each slit. Experimentation does not yield that result however and QM is required to explain the interference pattern that we actually obtain.

Ultimately, classical physics fails us.

As per the discussion above, Heisenberg makes probability fundamental to the universe whether as an actual quality (as in the strong interpretation) or even if only as an unavoidable byproduct of the measurement problem (weak interpretation.)

Comment from Max L
Date: August 15, 2008, 11:50 pm

If there are infinite universes / infinite space, there are still rules that govern on a more macro scale, like entropy, or for biology, evolution. Universes are not giant cocktail shakers - they are particles that follow rules, and I find if unlikely that every single possible configuration of particles could happen to exist. There could be an imaginable animal which could never actually happen because the conditions which would make it evolve that way would, say, destroy the world.

Are there no debates about Greene’s “cocktail shaker” model?

Comment from lisa Emmons
Date: August 16, 2008, 12:06 am

I get the idea of the redundant universe - and I believe the opportunity is out there - but there is also the ‘random’ science - the same science that lets a drop of water choose to go off to the left then go down again - rather than drop like a very heavy rock.
Yes, if you studied them there is usually some minor partical in the drops’ way -but that is not always the case and even you can not account for them all

Comment from Ken Luallen
Date: August 16, 2008, 1:18 am

>>
Perhaps you could demonstrate specifically your justification for these conclusions. Specifically what are these constant dead giveaways of God’s existence? On what basis have you dismissed all infinity based theories?
>>

Rob,

Science holds that matter cannot be created or destroyed. In answer to the question ‘where did it come from?’ science’s answer is ‘it just is’. Utterly and wholly unscientific, delivered by countless accomplished scientists with straight faces.

That’s the irony of scientific atheism.

At its very foundation science insists on defining things, and for good reason — this is what makes the discoveries of science reliable and believable. This is great for understanding our physical world. But on the question of the origin of matter, the scientific community should simply admit that they cannot possibly reach an answer because science limits itself to matter that already exists. It can go no further.

Any honest inquiry into ‘where did it come from’ forces you to look beyond the material world as we know it - and thus beyond the realm of science.

Any problems with my logic in this?

I don’t believe I dismissed infinity theories except to the extent that they can ever provide an explanation of our existence. I’m all for math. ‘Infinity’ is the word we use for our human inability to comprehend the boundary of something, be it space or an equation. But we know everything has a boundary — it’s a very scientific principle except when trying to answer the greater questions of origin and space, at which point science starts referring to ‘the void’.

I could accept the existence of a void/infinity and call it a day or I could keep searching for an answer to what was before time and what existed before matter. My curiosity leads me to choose the latter. I just wish science would admit that there logically must be something bigger than science. (Even if it’s not the God I believe in.)

None of this is at odds with a theory of multiple universes.

(By the way I don’t think you took the low road, which would be name calling and arguing a point without attempting to support it. There’s nothing wrong with disagreeing.)

Comment from Parker
Date: August 16, 2008, 4:11 pm

This guy is absolutely wrong about the “finite configurations” part.

It would be true if every atom had to fit into a fixed grid of possible locations. But thats not true. In fact, if you look at just two neighboring atoms within a nanometer apart, there is still an infinite number of distances they can be from each other.

Imagine those two atoms are in a neuron in ones brain. Say the distance between them affects the strength of the neuron. A very small difference in their distance apart could yield two slightly different thoughts, leading to different actions, etc.

THERE! At 25 minutes, he even says “infinitesimely small”. So he understands that there are infinite possibilities within the small ranges. The guy is a fool if he actually believes that the world has a finite number of configurations.

Comment from Paul Kotta
Date: August 18, 2008, 3:46 pm

Some scientists get attention through actual achievements, others by coming up with far-fetched theories. Get a real job, Brian.

Comment from Pavliga
Date: August 19, 2008, 10:50 am

nice, definitely

Comment from William
Date: August 20, 2008, 2:22 pm

My comment is along the same lines as Clever Human’s post. Let’s assume there is infinite universes and infinite space and the rules that govern this universe also rule all other ones. Can one also assume that all of the particle movements that went into the creation of this planet from the outset also approaches infinity? If that is true does his idea of duplicates fall to the wayside?

Comment from Frank Glover
Date: August 20, 2008, 5:23 pm

It would be interesting to bring together any two versions of identical individuals like this. In each other’s presence, it seems they would *have* to behave differently in some manner.

And it’s not asking that terribly much. If any possible variation must exist somewhere, then there’s an infinitesmal but non-zero chance that there are two *adjacent* but identical galaxies, right down to identical Earths. They don’t all *have* to bebeyond the red-shift limit from each other, however much more probable that is…

Comment from Tim Coulter
Date: August 20, 2008, 6:41 pm

Okay, so we’ve got a finite array of things to arrange and infinite space-time in which to arrange them. But what happens when we run out of things to arrange? Or is matter infinite, as space-time is?

Put another way, say I’ve got three kinds of yarn and infinite time and space to knit things. At some point I will run out of new patterns, but won’t I also run out of yarn?

See also the discussion on AskMetafilter: http://ask.metafilter.com/99650/Is-the-amount-of-matter-in-the-universe-infinite/

Comment from Millie
Date: August 21, 2008, 6:51 pm

Ok, I have nothing against this Greene guy, but there is one thing that confuses me. Remember that Space episode (the one with Carl Sagan)? They were talking about that time capsule that they sent into space.

Well, if this parallel universe thing is true, than there are millions of little space capsules floating around in the universe, and if if we are all in the same universe, than there are lots of chances that we find one of the space capsules sent by the parallel planet. Will they, at the same moment find one too? Will all the parallel universes at the same moment find one?

Will we then know for sure that there are parallel universes/galaxies/planets? And granted, some of them may be the same, considering some of those universes are supposed to be the same, but didn’t Mr. Greene say that there were some that are slightly different? So if we did find a space capsule and it was slightly different, what would that mean?

If we tried to contact them, would we say the smae things? HOW WOuLD IT WORK???!?!?!!? It is driving me nuts!

Comment from Listened a second time
Date: August 22, 2008, 12:21 am

Thanks very much RadioLab and thank you Brian Greene! I thought that was a great piece of radio. Really interesting and thought-provoking. Took some very difficult stuff and made it as clear as possible to a lay radio audience with a limited amount of time. Great stuff.

Of course the big question is whether the universe is infinite or finite. And as Greene himself pointed out several times, that is still an open question, even if some of the current data points to it being infinite.

I look forward to further advances in cosmology and Radio Lab’s being there to explain them to us.

Comment from Dan
Date: August 22, 2008, 4:21 pm

>>Well, if this parallel universe thing is true, than there are millions of little space capsules floating around in the universe, and if if we are all in the same universe, than there are lots of chances that we find one of the space capsules sent by the parallel planet. Will they, at the same moment find one too? Will all the parallel universes at the same moment find one?>>

Millie,
I was just thinking along these same lines, i.e. trying to prove the existence of an exact copy of Earth by contact. To take your example, we probably wouldn’t know if the capsule that had reached us was our own or sent by some duplicate Earth. How could we know? The contents would be the same, and perhaps the effect on the capsule of traveling through space would be the same for both ours and the duplicate Earth’s. Tests run on the capsule itself might only tell us that it travelled a very long way, not that it came from an exact twin of ourselves or that it was our own having doubled back on its path. Along the lines of proving the existence of our twins, the test results would be inconclusive: neither affirming or denying either possibility.

Additionally, we could only track our own capsule so far into the universe. At some point we would lose contact. Then, presumably, we would regain contact. Question is: what have we gained contact with, our capsule or a duplicate? You couldn’t know if everything created on the Earth’s exact twin were themselves exact twins. The tracking signal would be the same.

Suppose that we could travel to our doppelganger planet. If you did, how would you know if you didn’t just arrive back at your own home? There would be know way of determining which was which. You might have just passed, like Brian Greene mentions, through some passage like you find in PacMan. You’d never know if you found a duplicate Earth. You’d never find yourself there to ask because your twin would also be travelling and most likely be roaming the Earth trying to determine if it was his or not. Everyone you asked would confirm you left Earth on some fool’s mission to prove some other Earth existed. How would they know that you weren’t the person they said goodbye to? How would you, yourself, know that you weren’t?

I wonder if you could ever prove the existence of an exact duplicate Earth. Could you contact them remotely, like on some super-spacephone? That’s a little facetious, maybe. My point is, since everything is duplicated between the two planets how would we ever know if any signal, ship or vessel that we sent out wasn’t ours returning when we received one just like it? There would always be an equally likely hypothesis as to why it was our own, instead of someone else’s, and why there was only one Earth. We could never be sure.

I suppose there’s a possibility of running into yourself if you could travel from one Earth to another. I doubt, though, that we could ever experience a duplicate Earth and be satisfied knowing that it was indeed a twin. We could most probably only experience it as a mathematical possibility. One whose probability would be enhanced by the discovery of near-twins, similar but not exact. But that’s assuming a lot.

The question I have is, how much would have to duplicated in our solar system or even our galaxy for another Earth to be an exact twin our own? The entire geography of the universe would repeat numerous times. Wouldn’t it seem, if we stepped back far enough, that our universe was made up of nothing but repetition? But I guess, maybe, that’s what’s being proposed. I don’t know.

Comment from tlr3
Date: August 26, 2008, 10:04 am

hi! i look forward to listening to this.

i was wondering, though. could y’all maybe come up with a convention for the tags you put on your podcasts and stick to it? my player organizes podcasts by their tags, and y’alls’ keep changing. so, when i went to play this one, i couldn’t find it at first, but i see that’s because the artist tag is “Jad Abumrad & Robert Krulwich.”

i mean, that’s accurate, they are artists–but that’s never been the tag before! (usually it’s radiolab. or radio lab. or wnyc. or pro tools. you get the idea.)

thanks for considering my request.

tom

Comment from Philip
Date: August 26, 2008, 11:51 am

I admit I don’t have an extensive background in science, especially physics. But I don’t understand why Greene says that physics doesn’t suggest the universe is infinitely complex in the number of possible configurations of matter. Barbara Montero was critical of the materialist philosophy of functionalism in that it asserts that science has determined the nature of all matter, when this is highly unlikely, as we have no way of determining what we don’t yet know about matter. Quantum physics studies the smallest KNOWN particles of matter, but this does not mean that matter cannot become smaller than what we can observe. If matter is infinitely divisible, then the number of possible configurations is infinitely complex, so there is no finite variables to be infinitely repeated. And how do we draw statistics out of the unknown? For example, how can we claim the odds that space is infinite when we don’t have a view of infinity?

Comment from Ben
Date: August 26, 2008, 8:22 pm

Not sure whether Robert or anyone will respond to this, but is there a book someone would suggest not only about the different ways to arrive at the Multiverse(s) conclusion, but also the alternative brought up in the lecture about why a single universe solution is more likely. I am thinking something along the lines of how other authors have done great jobs of describing very detailed concepts in a not completely dumbed down manner (i.e. John McPhee). So any advice would be great.

Comment from Amanda
Date: August 27, 2008, 5:47 pm

After listening to Dr. Greene’s theory, it seems to me that his basic premise is that anything is possible and every possibility exists in some form or another, whether in this universe or another universe or many other universes.

With that in mind, there is something I would like to hear explained: if any possibility can and does exist somewhere, then in one of these other universes there must exist the possibility that there is only one universe, and that ours is this only universe, and other “multiverses” are only ideas. And if Dr. Greene’s theory is applied, then this idea of a singular universe must be as accurate as his idea of many universes. So the notion that there is only one universe must be as likely as the idea that there are many. Right?

Comment from SueB
Date: September 11, 2008, 11:21 am

I think this theory is similar to “the earth revolves around the sun” theory that drove men to feel insignificant.

What kind of egos do we as humans develop to HAVE to be special? Is the raccoon raiding your garbage can special? Only when your kids give it a name, right?

Get over yourselves humans! You are insignificant and if that makes you scream you should get off your damn pedestal.

I find peace from the thinking about how incomprehensible the universe is, but I am agitated by so many myopic people who can’t see beyond their own property lines. It seems to hurts their head. Hang on to your ego!

NOTE: The audio at the end is obscenely distorted i could not listen to the conclusion.

Comment from feinberg
Date: September 24, 2008, 10:15 am

Philip i believe in what you question. If we can’t know either way, theories are not answers. So, do i believe a human sound/scream can travel throughout space indefinitely. Why not?! Sound would not end. Light would not end, in one direction or another. AH, but yes. The theory is, probably not, because of barriers. So the barrier from infinity presents the “end” theory. I not believe space goes on and on. I believe in an end, just as i believe GOD intended. Size is relative my friends but infinity is not.

SueB, you seem angry at the notion people are searching for wisdom. You may believe this is because some men are looking for significance, because of worldly insecurities, but for the most part we are just curious about our existence AND other existence’s!

Comment from Bryan
Date: September 26, 2008, 1:39 pm

Just another attempt to deny our true maker and savior Jesus Christ.

Comment from Susan
Date: October 4, 2008, 10:21 pm

Delightful interview Robert! I’ve studied Buddhism for a few years and as others have discovered in recent years it seems to have a lot of parallels with the understanding of Physics. The “field” & “cheese” discussion about 20 minutes in was the ringer for me, as it could equally apply as an explanation of the emergence of Dharmakaya, Sambhogakaya, and Nirmanakaya from infinite Space (or cheese), which is one of the ways that Buddhism explains the structure of “reality” or experience of all phenomena. To explain this further would take more skill than I have here. I’m glad to have this further illumination - which like most of your episodes (the Space episode particularly comes to mind) tickles my curiousity about the world and my perceptions of it.

Comment from Torbjörn Källström
Date: November 15, 2008, 8:40 am

One thing that I’m thinking about infinity is that people say, “with an infinite amount of possibilities everything will have happened.” I don’t think that’s the case. Even if you have an infinite amount of bananas, no banana will become an apple. Infinite amount of space doesn’t necessarily mean an infinite amount of possibilities.

Flipping a coin an infinite amount of time doesn’t even mean you’ll get a single heads because the result of a coin toss isn’t really defined by how many times you throw it but how you toss it.