What's the Fabric of space made out of?

Sorry to be a wet blanket; but I recommend caution. These books may be fun; but they are not really good introductions to modern physics. They tend to get panned in review from people who are knowledgeable in physics, or experts in eastern philosophical thought. The best part of these books is their real potential to turn people on to the fun in physics; and that is a crucial first step. However, to make further progress there are things you'll have to unlearn from these books.It's been a long time since I read these. Actually, I only read TTOP; and glanced at DWLM. My comments are thus second hand.Apparently, "The Tao of Physics" was inspired to a great extent by the now almost defunct "bootstrap" model of particle physics proposed by Geoffery Chew, which has been pretty much replaced by the quark model. Physicists reviewing this book seem to vary from "total crap" to "good introduction but out of date". Many folks seem to think it is "preaching" a bit much; which is awkward since the progress of physics appears to have passed it by.I don't have a good alternative recommendation, as particle physics is not my thing. But there are a number of contenders that are much more up to date.The Dancing Wu Li Masters appears to be significantly worse. The author is a journalist, but the physics was apparently largely ghost written by maverick physicist Jack Sarfatti. Extreme caution advised.(By the way; maverick does not mean "wrong". But it does mean long shot; and it also means risky as a general introduction to physics.)My comments here should also be taken with caution; I've not looked into it in great detail.Cheers -- Sylas

What Sylas, and Ned, and Feynman, are pointing out is that it most definitely is an open and shut case that the universe fails to conform to your intuitions. That is as open and shut as anything ever gets in physics.Ned and Sylas and Feynman can admit to unknowns; but we also acknowledge other things that are known. Science does not learn everything in one fell swoop; but we do learn some things. It is this latter bit that you don't seem able to accept... and this comes across as arrogant as well, not that it matters much.Sometimes what we know violently conflicts with normal intuition. Quantum physics is a case in point. This does not mean we fail to know. It means we fail to intuit. There is a difference. We know the models, and we know how to apply them and we know they work; but trying to get a mental picture of it all is just about impossible. This is what Feynam means by "no-one understands quantum mechanics".But as Sylas, and Ned, and Feynman all point out, relativity is much easier. This is the bit you have been rejecting; but it is as solidly known as we get in science. Calling this "arrogance" has become for you a means of avoidance. It would be wrong for Ned or Sylas or Feynam to pretend that such basic discoveries as geometry for spacetime are somehow dubious or unknown or not understood. Your ideas HAVE been totally falsified. Not the infinite space part; that remains plausible. You seem to have everything else wrong; and you seem to think it arrogant when people dismiss your intuitions and common sense as irrelevant for dealing with real physics. We aren't claiming to know everything. Some things (like curvature and expansion of space) are most definitely empirically verified as basic factual discoveries; and the various alternatives (tired light, scattering) have been totally falsified by empirical evidence I have pointed out already in the thread.Cheers -- SylasThis message has been edited by Sylas, 03-14-2005 05:05 PM

Hi Lyndon; welcome to EvCforum. We're a basically friendly crowd, but pretty robust in debate. Criticism of your model in no wise mitigates a sincere hail fellow well met.With respect to tired light, the only kicking involved is spasms of the corpse. It has essentially no support whatsoever in the literature, and with good reason. This model is disproved by supernova light curves, by the perfect blackbody spectrum of the CMBR, and by the lack of scattering in very high red shift objects.You're also badly out of date with the so-called "oft-quoted" value of 64 km/s/MPsec value for the Hubble constant.There are two camps; neither of which much like the value 64. Alan Sandage continues to argue for low values: 60 or less. Wendy Freedman continues to plumb for values over 70.But most commentators now defer to the unprecedented precision of the WMAP team, using a wholly independent technique, which gives 71 km/sec/MPsec give or take 3.5.The debate is not over; but Sandage is IMO looking shakey. His most recent arxiv submission is much less definite about H₀ values, and recent work by Kanbur et al on the Cephid distance scale may point to a resolution. In any case your prefered value of 64 is not a serious contender; and your use of three significant figures in the inverse is not warranted by any observations.The ball park comparison of magnitudes for H₀ and hr/m is not interesting. Play around with constants and you can get all kinds of crude similarities. This does not mean anything; and the tired light notion is decisively ruled out by the other observations I mention.Cheers -- Sylas (with a "y", not an "i")This message has been edited by Sylas, 03-15-2005 05:30 AM

My original post should have been quite clear, and you'll see the same thing in many papers on this subject. As is standard in scientific writing, I give a quick survey of prior work and alternatives. There are two main groups, which have incompatible results. Saha, Sandage et al are the low values; and Freedman and the KST group have the high values. They can't both be right.The WMAP group confirms the Freedman KST values, which means (as I said previously) that Sandage's group is in trouble. The error bounds from WMAP are 67.5 to 74.5 (71 plus or minus 3.5). Freedman's KST group is proposing 74 plus or minus 7. (67 to 81) So KST and WMAP are compatible; but Sandage is incompatible with both.My post was clear: Sandage looks very shakey; so I'm betting on WMAP.Your approach, of averaging, is precisely the wrong way to approach such a scientific dispute. If one group says 57 +/- 4, and another says 74 +/- 7, you don't average them. You try to find out who went wrong.I see you are particularly keen on a value proposed by nine years ago by Riess, Press and Kirshner. These guys show the correct way to manage this kind of issue. It's no good just looking over the old papers and trying to combine incompatible claims. You have to look at the data. This is done in Cepheid Calibrations from the Hubble Space Telescope of the Luminosity of Two Recent Type Ia Supernovae and a Re-determination of the Hubble Constant, by Kirshner et al, to appear in the Astrophysical Journal and now available at astro-ph/0503159.They propose the source of error which led them to make the incorrect estimate back in 1996, and show how the errors arise from poor data. The explain how to deal with it, and perform an improved analysis on better data to obtain 73 +/- 4 (statistical) +/- 5 (systematic). So now we have three groups all around the low 70s, with error bars that exclude 64. (Kirshner et al 2005 arguably include 64 as an extreme; the others do not.)The icing on the cake is that this means the very person you cite most prominently for your figure has now published their own analysis of the problems in their own work, and have revised appropriately.Your suggestion that different results correspond to different electron density is bizarre. The groups are not looking in diverse directions; but using different yardsticks. More seriously, your invocation of varying electron densities immediately knocks out any association with an absolute value of hr/m, which has no component for density. So the hr/m equation is irrelevant.This was always a consistent problem with your work. There was never a model that made sense of the hr/m coincidence; and if there was such a model then it would be falsified by a further dependence on density of electrons. So there is nothing to explain in H=hr/m, which is just as well because H is bigger than hr/m.Then you actually give a different equation anyway! Your real analysis appears to use 2nhr/m, where n is a density figure.Now we have another horrible problem with your model. You only consider electrons. That's not sensible; the intergalactic medium is not composed all of this one particle; and that blows the whole analysis out of the water. So does the Lyman Alpha forest, which shows clearly that the intergalactic medium scatters wavelengths preferentially.But by far the most serious problem with your whole presentation is that you have merely ignored without any comment all the empirical refutations of tired light. Supernova light curves. Focus in large red shift objects. And blackbody spectrum of the CMBR.One final point. When we name some model or theory or paradox after a person, WE do it. Not them. The only person who speaks of "Ashmore's paradox" is Ashmore. That is a bit of a give away. Also bizarre is your excitement at having a paper accepted for a peer reviewed publication; with no mention of what publication accepted it!Sorry Lyndon. You’ve got nothing here but an avalanche of errors, and bitter experience tells me that nothing on earth could persuade you to see that.Ah well. Thanks for dropping by. I’m happy to continue, but I see no prospects for a happy resolution.Cheers -- SylasThis message has been edited by Sylas, 03-15-2005 07:48 AM

Of course. It is only an analogy after all, and like any analogy it fails at some point. But you can improve the analogy by thinking of buttons glued on a balloon. The buttons hold together at the same size despite the glue trying to pull them apart. Galaxies are held together like this by their own gravity.I've previously explained this in more technical detail in other posts.I also have a response ready for Lyndon; but am waiting to see if a new thread should be formed. I'd like to see the existing posts and thread of discussion on tired light maintained, however.Cheers -- Sylas

No problem; you did nothing wrong. This is actually a compliment. The topic is interesting and deserves it's own thread. I'll propose it. I wish there was an easier way to move posts. (Is there?)Cheers -- Sylas

It does not address the point of the analogy at all. It avoids it, and by this stage it looks to be deliberate. Deep down I am pretty sure you are merely switching off and refusing to learn. It's your choice.

Analogies are useful for someone who is actually interested in learning, to help them grasp some aspects of the more detailed mathematical models used in science. They also provide scope for others to make a lot of red herrings that just don't correspond to ANYBODY'S notion of the universe.You have your own beliefs, buz, and that's fine. It is clear than nothing on Earth will shake them; no problem.But as a simple matter of being sensible about the role of analogies, you should appreciate that whether you accept the findings of modern physics or not, it is a perspective that you don't really understand very well and which other people understand a bit better by virtue of having studied it.Ditching analogies because they are not "analytic" would be stupid, because then we'd be left with nothing to help people who can't manage tensor calculus. Analogies and mental pictures are vital for helping someone develop their understanding. You can use them to help get to the point where you can start to tackle the full analytic understanding; but by that point you should be using some textbooks rather than web posts. It is perfectly clear that no-one will ever convince you of the nature of space. But comprehension is different from agreement; and comprehension is required before agreement or disagreement can even be meaningful. You have not got to comprehension yet.I have explained about galaxies holding their size several times, you still have this wrong; in the sense that you continue to misrepresent what is proposed in physics. The same would be the case for anyone who has not studied the matter in detail; a novice is bound to misrepresent matters somewhat and they get better as they learn more. Your problem is that you do it with such confidence, and without any real recognition that you need to understand the model before you can meaningful describe what is wrong with it.What holds a galaxy together is not any failure of space to expand, but rather that the stars of a galaxy move to maintain the same size. I’ve pointed this out to you previously, in (for example) See, for example, Message 271, and few other posts.A galaxy is actually a collection of objects in continuous motion. (And this is another difference between dots or buttons on a balloon.)We can address this with another analogy. Imagine lots of ants walking all over the balloon as it expands. To grasp what it means for a galaxy to hold together, you can think of gravity being something a bit like a nest of ants who like to communicate by touching feelers. They are bustling around on the balloon all the time, but continually stopping to touch antennae with each other. The whole nest of ants will thus continue to occupy roughly the same area even while the balloon on which they walk is expanding.Now of course, this analogy still is not a full analytic model. One of the differences with the analytic model gets right back to the topic of the thread. A balloon is made of rubber; it has fabric. This just lets us visualize some of the geometric aspects more easily; but in physics there is no rubber, no fabric. There is just geometry, and expansion is an aspect of it. And if you are willing to let it, the balloon analogy can help you understand some aspects of the model, without having to learn tensor calculus.It is NOT a case of the space failing to expand inside a galaxy. It is a case of the stars continuing their local motions to maintain about the same separation distances while the space in which they move continues to expand.I don't care if you don't "agree" with this, and my aim is not to convince you it is true. I'd just like you to get to the point where you drop some of the misrepresentations about the content of the models you disagree with. But even if you never manage that; at the very least I will continue to point out for any onlookers where your criticisms involve actual errors in describing what the models used in physics actually propose.If you go off into yet another school of red herrings about how it is "illogical" that space expands, or that expansion of space would necessarily mean galaxies increasing in size, then you are not even comprehending the models used in the physics; which makes your "disagreement" rather pointless.Sheesh but this is aggravating, buz. I honestly don't care whether you agree or not, but your continuous ignorant misrepresentations of the implications of basic physics, and your refusal to accept that people who have studied the matter are in a position to try and describe its actual content, is ridiculous.Sylas

Its geometry. You've been given this answer many times, and your only response is to shut your mind to it. It is illogical and irrational to refuse to accept the mathematics. The expansion of space is, as a matter of fact, tied to the stress-energy tensor; but that gets into deep waters of tensor calculus again. Your intuitions about energy are not going to be reliable here. You have to learn a lot more physics before you can say anything sensible about energy in relation to expansion. Of course it is now obvious that you will prefer to trust your intutition rather than the collective work of several generations of working physicists. Calling this behaviour logical or sensible is a travesty.Cheers -- Sylas

There are not even points in space then. A "point" is an abstraction, not a thing, used for convenience to talk about space. All our natural laws and mathematics and so on are abstractions, used to help give a description of how the world works.Here is a fact of life. Anyone who measures the speed of a light in a vacuum gets the same result, no matter where the light comes from or in which direction it is going, or how fast they are moving.Do you think this is "logical"?This is very different to what we normally expect. For example, if am standing beside the traintracks, and I throw a baseball at the train (and perpendicular to the tracks) at 120 km/hr, then I measure the ball moving perpendicular to the track at 120 km/hr.But if there is a train moving at 90km/hr along the track, then an observer in the train sees the ball travelling diagonally to the track at 150 km/hr.On the other hand, if I shoot at a spaceship in a vacuum with a laser beam, then it does not matter how fast the spaceship is going, or in what direction. I and the spaceship both see the photons moving at 299,792,458 km/sec.We express this a general law about all velocities; and velocity is an abstraction... a useful one.This very unintuitive discovery is a basis of special relativity. Let me know if you can accept this as a fact of life. If so, we'll go on to consider a fact about general relativity.Cheers -- Sylas

Apologies folks; most of you are trying to help buz with a simple Newtonian analysis. I can't resist adding a wrinkle. Note that the claim about stop watches seems "logical", but it turns out to be false. They are equal in the Newtonian physics, which is a plenty good enough approximation to answer the questions being asked.But if we get really technical, it turns out that the stop watch on the moving train will record less time from drop to contact. This effect is called time dilation, and it is measurable using very precise clocks even for the velocities of an express train. It may seem illogical; but that is a mistake of confusing the role of logic.The earliest direct measurement of the time dilation effect was back in 1971, with atomic clocks placed on aircraft, flown around the world and returned to a common location. The times recorded on the clocks varied depending on whether they remained at the airport, or flew East-West, or flew West-East. It is a famous experiment, called the Hafele and Keating Experiment, and reported in Science magazine 177, 1972 (p 166).You've have to be very very precise indeed to pick up a difference in the times in the trani example. It takes about 0.5 seconds to fall 1.25 meters. Suppose that the stopwatch on the train records 0.5 seconds, from drop to contact, and that the train is moving at 100 km/hr. An observer outside the train will record the time from drop to contact as being 0.500000000000002 seconds.Is this "logical"?Cheers -- Sylas

This is not an "analogy". It is a a thought experiment. It is an example of a certain situation, for which we can perform calculations to determine the results, and then check if our calculations actually match up with the real world. The reason for having a vacuum is technical, but it does not actually make a significant difference. The time dilation effect mentioned in my previous post turns out to be an aspect of the same phenomenon.The speed of light is the same for all observers. It makes no difference how fast the source of the light is going, or how fast an observer is moving. If you move towards a photon source, you still them coming at you at the same speed as if you are moving away from the photon source. Weird! Illogical! Fact of life confirmed by many experiments and observations!Cheers -- Sylas

My point will be made whether you are in a vacuum or not. The differences in values obtained are trivial. I was trying to give an example in which there is something (photons in a vacuum) moving at the same speed for all observers. But we can calculate for other examples if you prefer.Let's forget photons and consider the eagle example. This is a different example, but we can solve it.You have a aircraft flying at 900 km/hr. An eagle inside the cabin flies down the aisle at 100 km/hr (from the cabin's perspective).The question is... how fast is the eagle moving relative to the Earth outside the cabin?Newtonian physics says 1000 km/hr (900 + 100).Einsteinian physics says 999.999999999999923 km/hrWhich one do you think is closer to correct? How do you decide?Try actually answering this question. Just give it a shot.Cheers -- SylasPS. By the way, you get the same numbers for the eagle flying outside the plane and in the opposite direction. If a plane is flying East at 900 km/hr, and an eagle is flying West at 100 km/hr, then the speed of the eagle relative to the plane is 999.999999999999923 km/hr; not 1000 km/hr.PPS. Just for fun; the exact formula used get the relativistic "addition" of velocities x and y given in km/hr isPPPS. Thanks MangyTiger; I have edited this post in response to your reply. In my first "PS" I originally had the eagle flying east. Have now corrected it to read "West".This message has been edited by Sylas, 03-26-2005 03:38 AM

The basic formula to use is the Lorentz transformation. Use this, rather than trying to work with length and time contraction.We locate things in spacetime with Cartesian co-ordinates. I'll use x for east/west distance and t for time. Let (x,t) be the co-ordinates for one observer, and let (x',t') be co-ordinates for another observer who sees the first observer moving at speed v in the x direction. Both co-ordinate systems are synchronized to a common origin (0,0)Then the Galilean transform (used in Newtonian physics) for mapping from one to the other is Using c for speed of light, and γ = 1/sqrt(1 — v²/c²), the Lorentz transform is Suppose the first observer sees something (like an eagle) moving from the origin (0,0) at velocity u. Then at any time t, they see the eagle at location and time (ut,t)The second observer (who sees the first moving at speed v), sees the eagle at Velocity of the eagle is distance divided by time, the gamma factors cancel as does the t, and you are left with Our first observer is in the aircraft. Our second observer is on the ground, seeing the first observer moving at v = 900 km/hr. Speed of light is exactly 1079252848.8 km/hr, and c² is the factor I gave in my previous post.Now let’s do the same thing the hard way! Working with dilation factors is very error prone, since it is very easy to slip in an assumption of common simultaneity and get the wrong answer. You need to take three factors into account to get the right answer. These factors are all at odds with normal intuition, and I give them in order of increasing weirdness.

1. Time dilation. A moving clock runs slow. It takes γt seconds for a clock moving at speed v to get from 0 to t.
2. Length dilation. A moving object is shortened. If the length of the aisle is x in the aircraft, then it has length x/γ from the ground.
3. Simultaneity. Clocks that are synchronized from the point of view of the aircraft are out of synch from the point of view of the ground. In the cabin, clocks at both ends of the aisle read zero at the same instant. But from the ground, the clock at the end of the aisle reads zero γvx/c² seconds later than the clock at the start of the aisle.

In the aircraft, the eagle gets up to flying speed in the galley, and enters the cabin aisle at its cruising speed. It maintains a fixed velocity until it crashes into the wall at the far end. All clocks on board read zero at the instant that the eagle enters the aisle at its cruising speed. The length of the aisle is x, and the eagle hits the end wall at time t. All clocks on the aircraft read t at the instant of this collision. The velocity of the eagle is therefore x/t. Let this velocity be u.From outside, the length of the aisle is x/γ. The eagle starts flying at time 0, and crashes into the end wall when the end clock reads t. But the end clock took γt seconds to get from 0 to t, and it was reading zero γvx/c² seconds after the eagle started. Thus the time of the eagle’s ill-fated journey is During this time, the plane flies at speed v, covering distance vt’. The eagle flies an additional distance x/γ which is the length of the aisle. The total distance from start to finish is thus These are the same formulae obtained form the Lorentz transformations directly, and so we proceed as before.Cheers -- Sylas

That is correct.The reason I used vacuum is because the speed of light in a vacuum is the same for all observers. This means we can answer the question without doing any calculations. But the effects of air on light are so small that it makes no real difference, and so the point stands whether you are in a vacuum or not.The speed of photons fired at a train or a spaceship are the same from the perspective of the train, and from the perspective of the person holding the photon source. If you are moving towards a photon source, or away from it, you still see the photons moving at the same speed. This is not what we would expect in Newtonian physics.This is relevant to the fabric of space topic. Before Einstein, it was commonly thought that light was waves in the fabric of space, called the ether. Many experiements have confirmed that this ether model fails. However, space can still be curved. The examples we are considering here don't deal with curvature yet; but they are a necessary pre-requisit, and they do show that "logic" or "intuition" that assumes some kind of absolute space give the wrong answers.Cheers -- Sylas