The Fabric of the Cosmos (documentary series)

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I've noticed that Youtube has disabled embedding of these videos, so her's part 1 again:

http://www.youtube.com/watch?v=wy9gXKwRpXc

Also, whoever's uploading these videos has also recently put up part 2 of the documentary:

http://www.youtube.com/watch?v=Rp3_cPRQSh0&feature=channel_video_title

http://www.youtube.com/watch?v=PDkuo90lPGI&feature=watch_response

Here are the last 2 episodes of the documentary. The third episode covers quantum mechanics and the last one is about the multiverse. Enjoy:

http://www.youtube.com/watch?v=8eZqQUdWURs&feature=channel_video_title

http://www.youtube.com/watch?v=-FGgkfsMpCs&feature=channel_video_title

Thanks for calling this to my attention Jono. I read both of Brian Greene's books and thoroughly enjoyed them, especially the second where the subject was with what at first blush would seem so etherical; the nature of space and time. I haven't seen either PBS series, except for a cursory review. I plan to watch both series. The black guy with the long grey hair is the teacher ion the Teaching Company's String Theory course, which I am now watching. String Theory and Quantum Mechanics are wonderful jump-off points for some really fun thinking about what might be. During my reading of Greene's books I had some thoughts that I really enjoy.

1. Since spacetime can be bent by gravity, space is not really what we think it is. When space is warped, is it possible to take a shortcut across say a U-shaped bend (Startrek warp)? If it were possible, I guess the trip would be taken outside of spacetime; or perhaps outside of the spacetime that we can sense. Perhaps the shortcut is through one of the theorized dimensions. Connect that with quantum entanglement and you can begin to wonder whether the entangled particles are actually the same particle in one or more of the theorized dimensions but not in our 3 or 4 observable dimensions. If space was born with the big bang and continues to expand, then all distances as we know them are constantly changing. If the distances are changing, what does that mean for the flip side of space; that is time? What does it mean to say that time expands with space; does it mean that seconds tick by more slowly? Fascinating ideas; for me anyway.

2. Could Dark Energy be a pull outside the observable universe rather than a push that originates within? Or perhaps it's a leakage of gravity from branes other than the one upon which we reside? Greene speculates that gravity is the only force that can travel between branes when he speculates why gravity is so weak a force.

3. Is there room for religious-like faith in these theories? If there are indeed 10 or 11 dimensions, why should our existence be confined to 3 or 4? When our body decomposes in our known dimensions, does some part of it continue to exist in other dimensions? Maybe our consciousness exists in a tiny grain of some Calabi Yau Manifold. One can believe anything that he can have faith in. All that it takes to have faith is a reasonable and coherent theory of how things are. I must admit, I am searching for something to believe in in all of this.

Thank you for posting these links. I'm very slowly downloading them using my crappy dial-up internet connection. I've managed to watch the first 15 minutes of the first documentary now. YouTube certainly doesn't make it easy for anyone with slow internet connections to get the content - in fact they go out of their way to make it almost impossible for anyone without broadband to watch / download anything longer/larger than a few minutes.

I will have a third attempt at downloading the first documentary again tonight. Trouble is my internet service provider automatically drops the internet connection every nine hours and YouTube often bombs out and won't allow resuming of broken downloads, so it looks like I may be limited to only watching the first ten or fifteen minutes of each documentary. Better than nothing though.

Thanks again for posting the links.

It's a pleasure. I'm glad that you guys like the documentary series.

@Tallyman, unfortunately that's one of the downsides of dial-up internet. Not only is it slow, but a dial-up internet service is charged via a telephone account. So be careful that you telephone account doesn't skyrocket. I'm glad that you liked the documentaries though.

I hope I'm not suggesting this thought in ignorance, admittedly I'm not a quantum physicist or anything, but they mentioned something about dark energy and the propulsion of stars and galaxies away from each other. Are they implying perhaps that as stars die or as the universe seems to get colder or older that the energy, rather than getting lost, is kind of going to the background broth itself and perhaps fueling the increase in strength of dark energy?

Watched the second video and I'm a little confused. I disagreed on the book example - the pages fell exactly as they were going to since the big bang, he could rewind and watch the video as many times as he wants (probabilities are fictional animals), and for the past not having entropy coming to order - we're funny about this one. That book, before he wrote it, was a grove of trees, some chemical components of ink from around the world, some cotton, flax, or whatever the cover is, and a cloud of diffuse ideas he had between perhaps some microsoft applications, some scrawlings in notebooks, and perhaps earlier papers he'd written. The human game - we call entropy going forward entropy, we call entropy going in reverse 'elegance' (such as the formation of his book).

The time thing was tough to get my head around. So pretty much if you travel at light speed to a given point and back you get hit with a penalty both ways, and you can entertain the notion that history is widening behind you as you pick up speed but you won't be able to do anything with it because the second you turn around and try to chase it you're future-gazing again. That's brutal. On the wormhole thing - wouldn't cheating usually negate the effect in the sense that it would be like barely moving but skipping a vast range of space? It might be a good road to take if you want to shed some space-time speeding penalty, obviously you'd be playing a few less hands of bridge during the trip to whatever solar system or galaxy you're going to, but I'm not sure how time travel could come of that unless his reference to wormholes was disconnected from the movement backward or forward issue.

Not necessarily. A constant cosmological constant can account for the accelerating expansion of the universe. However, there are models such as quintessence, in which the amount of dark energy actually does increase with time. Source:

http://en.wikipedia.org/wiki/Dark_energy

Where is all the extra quintessence coming from. It sounds like a conservation law being broken.

ruveyn

Ok, entropy is a measure of disorder. What the second law of thermodynamics states is that, over time, the amount of disorder increases. What the book comparison is illustrating, is that when you tear it up and throw the pages into the air, they will land in a manner that appears disordered as opposed to the orderly way they were arranged when still bound as a book. The law of increasing entropy refers in a sense to the "ordering" of atoms molecules and particles, which by comparison to the book example, generally become more disordered over time. That being said, your argument is partly correct in that just as there are physical laws that determine where each page will land on the ground, there are physical laws that would we each individual molecule will move etc (note: this is only according to classical physics, since Boltzman didn't know about quantum mechanics). However, note that it would be practically impossible to solve, for example, 10^32 simultaneous equations for each individual air molecule in the room you are sitting in order to derive the bulk properties, such as temperature, pressure and even quantities such entropy, of the gas in that. Thus, the only practical way deriving macroscopic properties from the microscopic theory is by using probability theory, since even supercomputer would need a length of time, as long as the entire age of the universe to solve everything exactly. Utilizing probability theory to achieve this instead, is exactly what Boltzman's theory does and that's what lead's to the laws of thermodynamics, it's what we call an effective theory.



Yes and no. A wormhole would be sort of like a shortcut through space. As an analogy, consider a train going through a tunnel in a mountain rather than going around it - it would get to its destination quicker because the route is shorter. As for why anything that seems to travel faster than light would imply backward time-travel, look up the tachyon antitelephone paradox:

http://en.wikipedia.org/wiki/Tachyonic_antitelephone.

Basically, if a particle had to travel from point A to point B in a time less than it would take a light beam, then there will always be a reference frame in which event B occurs before A, i.e. it reaches its destination before it departed in the first place, (the time travel bit). When a particle travels through a wormhole, technically its not actually breaking the speed of light barrier (and thus violating anything in special relativity), since its speed through the wormhole would always be beaten by a light beam traveling the same route, just as the train is not going any faster when it travels through the tunnel in the mountain. However, from the perspective from outside the wormhole, the particle still appears to have moved faster than light, so the tachyon antitelephone situation still occurs. This would actually be pretty cool if wormholes actually existed but unfortunately, there's no reason to believe that they do.

To be perfectly honest with you, I don't think even the people who work on quintessence models know the answer to that question. That's why I don't like such models. The specific models where they talk about increasing dark energy, they talk about something called "phantom energy" and I have no idea where it comes from. For example, see here:

http://arxiv.org/abs/astro-ph/0302506v1

my personal view on dark matter is that of membrane theory,
spillover gravity from adjacent universes, it could change over time and it explains why there is no direct interaction between dark matter and normal matter.