Schneibster

I'm sorry, "You just cannot use words (eg faster) that include time to define it" doesn't seem to me to mean anything. I provided equations in post 86. Did you understand them? They're not very hard. Any decent graphing calculator will do them. Have you played with them like I suggested? Time is a dimension. Unlike the other three "big" space dimensions, which are all circularly symmetric and whose angles and distances can be calculated with circular trigonometry, however, time is hyperbolically symmetric with respect to all three space dimensions. In relativity, the space dimensions and the time dimension can be exchanged with one another to describe different frames of reference. To a person whose frame of reference is moving at a significant fraction of the speed of light, significant physics transforms are necessary to define each observer's view of the others' circumstances. In fact, if you examine the equations I posted in post 86, you will find that the t dimension becomes a combination of t and x, and the x dimension becomes a combination of x and t. In other words, to convert these different observers' viewpoints into one another, each must see the other as experiencing a significant amount of time as motion in x, and a significant amount of motion in x as motion in time. This is the result of the rotation that the hyperbolic trig version of the Lorentz transform describes. Once you understand that time and space are insensibly converted into one another by nothing more complicated than going very, very fast, you are on the way to understanding the real meaning of relativity. There are rotations you cannot see and they happen all the time, but you're too big to notice them, and too slow, and too massive. If rotations like this happened all around you all the time you would die of radiation sickness.

That was my point; obviously they're not happening around here any more. Make what you will of it. But don't pretend it disproves Eternal Inflation. It just challenges the most naive version of it. You just don't want to admit that the exact physics of this particular region of spacetime is a random outcome among an infinity (or anyway a significant fraction of 10300) of potential outcomes. Could you explain why, please? Incidentally note please that a universe developing in your shirt pocket would give you radiation burns and constitute a major hazard to life if it were happening all the time around here. But there are two huge voids on either side of us that hint that they spat out everything that makes us up and it coalesced in between them and then the universe froze, sort of. And now everything is just expanding at the same fairly slow rate, which is slowly increasing in the beginning throes of a new exponential expansion that will culminate in an ever-expanding sterile universe, or, perhaps, a new fertile ground for the occurrence of new vacuum bubbles and new universes. The forecast is for things to remain the same for a trillion years or more. After that the expansion will either render the surrounding expanse of the universe and the multiverse sterile, or something unusual will happen.

From our viewpoint as mammals, that's a definition of time; however, it's only a measure of how we see it. Remember we are constantly moving in the t direction at the speed of light from our own relativistic viewpoint. The faster we move relative to another observer, the less t they see us traverse and the more x, y, and z. We're rotated that way, relative to them. The situation remains symmetric until either they accelerate and catch up to us and pass us, or we turn around and go back. That's the explanation of the "twin paradox." That equation I printed above, about t and the hyperbolic sinh and cosh of s turning it to both t and x. That's the real math and it's all the math, Lizzie. It's relativity. The rapidity, s, is a hyperbolic angle, Lizzie. You should look up Poincaire and check out some of Escher's drawings of Poincaire hyperbolic universes. You should take a cruise around the values of s with a graphing calculator. Hyperbolic geometry is very important to a clear understanding of relativity. It is the geometry of time. And the equivalent, in a hyperbolic dimension, of the "right angle," is an imaginary number. You can't get to a "right angle" in spacetime to the time axis. It is an imaginary value. You would no longer exist. And that's why you can't accelerate to the speed of light, and why the speed of light is maximal. Because of the definition and curvature of time. This is merely a repeat of the conversation about tachyons. If anything could turn into tachyons, we could no longer see it and it would appear to violate mass-energy conservation. Anything slowing down from tachyon speed would, in turn, appear as if from nothingness, violating mass-energy conservation the other way. We have never seen either of these. Nor evidence of them in the farthest pictures we can take. The implication of this is something going FTL appears to go backward in time. I hope folks understand that anything real must therefore first attain an imaginary angle, and then go past it and disappear into backtime headed back toward the origin of the universe. That's two impossible things before teatime.I'll believe that a universe went forward in time from the origin, and one went back, and we're in the forward one, but other than that I don't see a time when anything could have disappeared into backtime, and not out of the horizon of our universe.

May I ask if anyone thinks Gravitation is a popular science book? Everyone is aware this is a textbook in the curriculum of relativity, and one of the few really indispensible ones, right? I cannot believe I am defending this textbook. This is an extremely surreal experience. Usually I'm the nutzo guy who's breaking the paradigm and being all rebellious and stuff. It's really weird transitioning to the old guard. Really weird.

Ummm, you really ought to read that page by Baez. A lot of people know Baez from his crackpot index, but he's also a mathematician and relativist of note, published and teaching in one of the foremost physics programs in the world.

Actually, I find the best pop sci has great analogies for understanding the consequences of the math, and the expectations it imposes on theory. I think anyone posting on an internet forum is either a researcher trying to pass stuff along, a non-researcher with formal experience in another field trying to understand and pass that understanding to querents in payment for the stuff from the researchers, or a poser.

I think you missed the part where I said it was a metaphor at the very beginning. http://www.scienceforums.net/topic/81805-what-is-constant-alpha/?p=792010 That is, note please, post number 4 on this thread. And that makes me question your purpose here, which is clearly not to argue about physics.

Actually, just so you're aware, the reason the term "landscape" started being used is because of the "fitness landscapes" of chaos math applied to evolution in population biology. And the "fitness" of a universe is a measure of how likely it is to support life like us, at least in our opinion. Other thinking life might have a completely different physical, chemical, and biological derivation, likely impossible in our universe; OTOH, it's almost certain that there's other life in our universe, using other energy gradients than our oxygen-rich atmosphere supports. I won't be surprised to find simple life in Jupiter (and yes, I meant "in," if you know anything about Jupiter you know that's appropriate). I'll frankly be surprised if there's no life there. It's a very rich environment with many potential flows to be tapped. OTOH I won't be surprised if we don't recognize it as "life" at first. Hopefully there's no one smart there to get pissed off and mount an extermination mission against the mites from the awful hellish Third World. Kidding. But only somewhat. The point is, even in our own universe's constants and physical laws, we can see more than one way for "life" to evolve, and even "intelligence." What Linde and Susskind propose is that many universes with all kinds of different physical laws can occur. Why are you, then, surprised that there is this universe that supports thinking beings, whatever that means, here and now, since all kinds of universes occur all the time? I would say if there is Eternal Inflation that every different kind of universe is being explored all the time. In fact, we are not unusual, but inevitable. And we will always occur in a universe like enough to this one. Leave the cream cheese in the fridge long enough and it will eventually demand the vote. Linde has universe fluctuations popping into existence all the time all over the universe. Obviously, thinking beings will only evolve in universes that support them. This is a lemma. Why do you deny it? It's obvious.

Sure; Eternal Inflation. I thought that was understood. Obviously there haven't been any popping around here recently. I don't see why it would have to affect the entropy of the universe any more than necessary to make a signature in the CMBR. And that's not much entropy any more. The universe went matter-dominant when it became transparent. It's worth mentioning that Susskind is a close personal friend of Andre Linde and has worked with him extensively over many years. His acknowledgement in The Cosmic Landscape mentions Linde very warmly, and not just in a list of other names. It's clear his thinking on cosmology has been strongly influenced by Linde; and also Alex Vilentkin and Alan Guth, both of whom he also knows personally and has worked with. I am pretty sure he had Linde and Vilentkin look the book over while he was writing it from the way he talks. Planck is awesome. You can really see the four low-n harmonics in the picture: http://sci.esa.int/science-e-media/img/61/Planck_CMB_Mollweide_625.jpg as well as the "cold spot" just to the right of and below center. I wonder what other interesting things the image is hiding if we could get a better projection. Or even just move the "midpoint" around to explore the image more thoroughly. I trust the human brain beyond any mathematical formula or machine for pattern recognition. We're so good we have a major problem with false positives. But if there's a pattern there, then there is a human mind that will spot it. That's the advantage of there being six billion of us. In fact, the whole Planck site is pretty good; this ESA press release has some of their best graphics, as well as a great overview: http://sci.esa.int/planck/51551-simple-but-challenging-the-universe-according-to-planck/ Enjoy.

I'm not sure why we're arguing about this. Do you know what a "metaphor" is?

I think she's gone a long way farther than I have. Note that if the string landscape is real, then all the other universes will forever remain beyond our horizon. The only clues will be from the CMBR. Technically, the CMBR is a hologram of the universe outside our horizon.

I seriously doubt much of anything in Gravitation is superceded. I would say a modern curriculum in relativity would be incompetently incomplete if it didn't include this textbook. I'd look pretty askance at any paper that claimed to refute something in Gravitation. It would need to include extraordinary evidence. I have to say I find the idea that relativity is "obsolete" or "superceded," well, quaint.

Relativity. And there is no "proof." That's pretty good evidence though. The spatial dimensions are right circular and the temporal dimension is hyperbolic. Here is the article on it, from John Baez: http://math.ucr.edu/home/baez/symmetries.html Here is the hyperbolic trig Lorentz transform: t → (cosh s)t + (sinh s)x x → (sinh s)t + (cosh s)x y → y z → z where, s, the "rapidity", is related to the ordinary velocity v by v = tanh s

http://www.technologyreview.com/view/421999/astronomers-find-first-evidence-of-other-universes/ contains news recent discoveries (last October) on this front. This is what I'm talking about. Incidentally it seems Roger Penrose was involved and made the discovery simultaneously with another person.

I think it loses a lot in translation.

Well if there's one of physical interest it will, by definition, be of cosmological interest.

It still looks local.

Sure IO. Enjoy.

Actually I'm still thinking about the Great Attractor but I don't see it as anything but a local phenomenon. Maybe we might have a discussion about "local."

The largest structure of the Universe, defined by Gamma-Ray Bursts

Don't get me started. I come here to escape from that crap.

We pretty much know where the universe came from and how it will evolve, and what its large-scale structure is; and we're spit in the ocean just like we always thought, with huge empty bubbles taking up most of space. Our little foamy spitty salient between two huge bubbles is called the "Virgo Supercluster." Ten billion light years thataway, is a huge empty bubble; a few billion thisaway over here is another one, half the size. The edges are called the "Her-CrB Sloan Great Wall" over in the small-bubble direction; the one in the opposite direction hasn't been named yet but takes up a ninth of the sky.

Wife cats and heart disease for me, and hopefully shortly less heart disease and more job.

I see Einstein as a purely local theory. It's different in other string universes. The string theory that will eventually describe our local physics will conform to Dirac and Einstein theory, among others. It will be degenerate with them in the low energy limit.