Martin

Great ambition! It is not a popular-written book, apparently. Today it is down to #16 on amazon bestseller list. I believe a lot is that he shows you the formulas and equations, which turns some readers off. But I like that aspect of it.

Too bad, I was hoping Bojowald has made important contributions to quantizing relativity and especially quantizing cosmology he got rid of the big bang singularity in 2001 and that began a line of research that includes now a growing number of people in quite a few countries there are some popular science journalism accounts of his work---and related work---if you want links

Severian, here you are! http://physics.nist.gov/cuu/Constants/ Go here and click "Universal" and you will get http://physics.nist.gov/cgi-bin/cuu/Category?view=html&Universal.x=74&Universal.y=9 There you will see a menu with Planck Length Planck Mass Planck Temperature Planck Time If you click, you will get definitions and current best values. In addition to this a value in Coulombs for the fundamental charge, or electron charge, is needed. The NIST site has this as well.

Severian, I still have a serious question. I assume you are familiar with Planck units. If you wanted to you could no doubt express some of the basic constants in physics in Planck terms, as opposed to the usual SI metric terms. what I want to know is this. Is it obvious to you that in Planck units the value of the Coulomb constant is alpha? that is, taking the electron charge as the unit of charge. If not obvious, can you at least prove it to yourself by a little algebra? If not then I have some explaining to do---my approach to discussing such things is not working

You give the correct conventional formula for alpha, here. I will rewrite it so as to be a little more legible. This is the definition I assume here: [math]\alpha = \frac{e^2}{4 \pi \epsilon_0 \hbar c}[/math] The value I use for most purposes is 1/137.036, because it is a little more accurate than 1/137, and I really don't need all the accuracy of 1/137.03599976. You are correct that at very high energies and short distances alpha increases. this is a good point to make:

for the non-string approaches to quantizing gravity, that is essentially any background-independent approach to Quantum Gravity the main thing to know about is Loop. Instead of examining everything on Rovelli's 1998 list, I would suggest just reading one thing if you want an introduction to QG: Lee Smolin An Invitation to Loop Quantum Gravity" http://arxiv.org/hep-th/0408048 this is a 50-page survey and intro for physicists in other fields who want to switch fields and do QG research. It is being submitted to Reviews of Modern Physics (a standard physics library reference for grad students looking for areas of research for dissertation). Sound like it might be too technical? Have a look. It is surprisingly accessible reading. LQG is the context in which the cosmological singularity has been removed and inflation shown to occur generically---and where the quantum operators measuring areas and volumes have discrete spectrum----Smolin lists some major results. My impression is different from yours---you see a lot of non-string approaches to QG "floating around" and i see one main approach making fairly steady progress. so would advise looking at that one first

You mean it was trying to make black holes and produced me by accident? Lucky you, Homer! It optimized for making holes and inadvertently got Life in the bargain!

Wait til you see the book Cap'n In the meantime, have you read the reviews? from the Statesman, Times byline http://www.thestatesman.net/page.news.php?clid=24&theme=&usrsess=1&id=50300 from last Sunday's "Scotsman" http://news.scotsman.com/features.cfm?id=849142004

Penrose is down to 12th place

"Strings, Loops, and Others: a critical survey of the present approaches to quantum gravity" Carlo Rovelli http://arxiv.org/gr-qc/9803024 This was the plenary lecture on quantum gravity given at GR15 6 years ago, just like this year at Dublin they had GR17 It is a conference they have every 3 years on relativity and gravity. Pages 1-14 list the various approaches to getting a quantum theory that is either a quantization of General Relativity or which handles gravity in some other way. Since 1998 the field seems to have narrowed some and in the non-string department most of the development is in LQG and its offshoot LQC (loop quantum gravity and loop quantum cosmology) for an up-to-date survey of LQG, related approaches, and applications to cosmology, see the plenary lecture given at Dublin GR17 by John Baez titled "Loop Quantum Gravity, Quantum Geometry, and Spin Foams" http://math.ucr.edu/home/baez/lectures.html#lqg If you click on "postscript version" you will, in my experience, get a PDF version if that is what you need. I dont do PS but I clicked on it anyway and somehow it was OK and I got the Baez lecture

God jana, that is really interesting. you have earned your keep for a whole month. now we dont have to consider any of those mediocre numerologist crazies. Because pauli has topped them all!

No. Do you know Bojowald? he is a nice guy. he answers email sometime. Are you in Germany?

to understand Smolin's Multi it probably helps to get familiar with some of the absolute numbers that shape our universe---the inherent proportions in nature. these are the same in any system of units because they are ratios-----dimensionless parameters characterizing the standard models of physics and cosmology (to quote Smolin page 29) so here's a worked example. Look at the NIST website of the fundamental constants of physics. you see a certain energy: planck energy. It is 1.956 GJ (actually they tell you planck mass but multiply by 299792458 squared) the colors of the hydrogen atom, its ionization energy, all that stuff is determined by an energy called hartree and if you look up hartree in NIST you see its ratio to planck energy is 2.229E-27 this is a number anyone in the universe would discover as a built in proportion of nature if they got into hydrogen colors----it's the hartree in natural units. -------pause------- I dont want to have to remember that but I do remember 1/137 and the reciprocal proton mass 13E18 and the proton/electron mass ratio 1836. What Im suggesting is square 137 and multiply by 1836 and 13E18 and take the reciprocal You get 2.23E-27 which is the hartree to the indicated accuracy. Swanson, I think, knows that this is trivial. maybe other people here do as well. the point is that it is extremely to calculate a lot about the world from just these 3 numbers. these are 3 out of some 3 dozen basic numbers that determine the universe and Smolin says they go down the hole and come thru into the new baby universe just slightly changed------like genes passed from parent to child----and good sets of genes (or numbers) are those which encourage the formation of black holes. so that conscious lifeforms is a byproduct produced incidentally with black hole formation. Some of the same things that help get you holes will incidentally be favorable to life St Francis of Assisi who said brother sun and sister moon and brother fire and sister death would also be saying brother Black Hole----we are the black holes cousins because the same kind of universe that is good at making them is good at making us. Because it makes lots of stable, long-burning stars, and has a periodic table with carbon chemistry, and soforth. Chemistry with elements like C and O, it turns out, helps gas-clouds radiate off their heat so they can condense and coallesce into stars more comfortably. Can anyone at SFN besides Everclear and me recognize the potential of the idea of this kind of evolution via Smolin Multiverse model?

yes, the Hartree energy will be easy to calculate. it is twice the ionization energy of the H-atom and from there all the energy levels are approx. just 1/n2 so all I have to do is calculate the hartree in the natural unit, the planck energy unit. that means divide the planck energy unit by 13E18, by 1836, and by 1372 planck energy is 2 GJ, so if we want we can get the answer in joules and compare it with what the NIST Fundamental Constants website says about the hartree.

Swanson, just to take a test-drive with the constants, I think I can calculate the colors hydrogen glows just using 1/137 and maybe 13E18 I might also need the number 1836 too, which I know you recognize as the proton/electron mass ratio. right now not sure what it will take. but those 3 numbers should be sufficient. do you poo-poo this, or do you find it interesting

good, Swanson, was hoping you might be around

For physics, as I see it, this moment in its history is characterized by an encounter with the absolute numbers and efforts to understand why they are what they are the particle Standard Model has about 26 pure numbers (this is taking Planck units as the units to express masses and stuff) and cosmology Standard Model has about 10 pure numbers so that is why Smolin says there are roughly 35 'dimensionless parameters" which we need to explain (see his "Scientific Alternatives to the Anthropic Principle" essay) and it doesnt hurt to just look at the top 3 because that shows the situation in a nutshell. Physics is encountering and being forced to account for these three numbers fine structure constant 1/137 planck proton mass ratio 13E18 cosmic length scale 2.7E61 the "cosmological constant" in this context just means the inverse square of the cosmic length scale-----and we dont even rightly know what value to attribute to it since we only just ran smack into it in 1998 with the data on accelerating expansion. I just picked the length scale to be roughly what Smolin says, so if you take its inverse square you get what they estimate for the cos. const. or "darkenergy"---it is pretty obscure but there seems to be some large length scale in the cosmos the other two are more straightforward and have been around in human ken longer-----1/137 and the reciprocal proton mass. the reciprocal of the proton's mass is 13E18, that is 13 quintillion, and nobody has yet explained this number, why it is that. A couple of years ago FrankWilczek, an eminent theoretical physicist, had a series of 3 articles in Physics Today about the number 13E18 and efforts to understand it. They are online if anybody wants. String theory has since January 2003 been thrown into some confusion by the number 2.7E61 Just one number will do it---in this case it was the cosmological constant. IMO the important thing now is to confront the basic absolute numbers and realize how ignorant we are and see what, if anything, can be done about it I am a physics-watcher and I chose to align my perspective with Frank Wilczek and Lee Smolin---so I see roughly eye to eye with them about this moment in physics history.

Well? what is the Panda version? I guess a Panda eats bamboo shoots and leaves so this has possibilities, and maybe it is offensive too, so you had better tell us Sayonara before Capn expires of curiosity

too late blike you already fixed everything this thread is useless

in a nearby thread Gun asked for someone to explain coulomb law this is a surprise for Gun in case he looks in here. here's an example, worked out in natural units---planck units. spread your thumb and tip of forefinger apart as far as you can that is about E34 planck length units. Imagine two charges E34 units apart. typical amounts of charge for something to have is E12 electrons so imagine the two charges are each E12 electrons. multiply the charges together---E12 times E12 is E24 square the distance----E34 times E34 is E68 divide E24 by E68 and it gives E-44 there is a natural unit of force and E-44 of that unit is a force of about 123 grams------roughly an eighth of a kilo weight or a quarter of a pound. Teachers dont like you to use grams or pounds or kilos of force they like you to use "newtons" and E-44 is right around 1.2 newtons. So we are almost done, we got E-44 for the force. But dont forget to divide by 137 The actual force between that amount of electrons that distance apart is NOT E-44 it is, instead, 1/137 times that. [math]F = \frac{1}{137} \times 10^{-44}\mbox{ natural units of force}[/math] So it would be 1.2 newtons divided by 137, whatever. Or 123 grams divided by 137. In other words about a gram. why such a small force. Because each charge is only E12 electrons (a trillion) and the electron is a small bit of charge and also you put the two charges pretty far apart----the spread of your thumb and finger.

we all the time experience static electicity things sticking to each other raising hairs on back of my hand, picking up bits of lint, giving shocks on a thick rug basic law is two charges attract or repell with a certain force which you can calculate western civilization is based on the idea that you can use algebra to calculate things and if you dont like to do that screw you---this is the fundamental tenet. so the basic act of the communion with nature is to calculate the force. it is very simple. You just multiply the two charges together and divide by the square of the distance separating! but then there is this constant called Coulomb you have to also multiply in to make it come out. Gun I worked an example of coulomb law for you in another thread: http://www.scienceforums.net/forums/showthread.php?p=73343#post73343

nearly right was that just a lucky guess? realistically, if you have to ask then this thread is probably not cut out for you, Gun. I am not teaching a review of basic physics in this thread. JaKiri and various others could set up a basic physics review thread. Maybe you should ask them to do it, or whoever you like listening to. Look, in the next thread I will offer an explanation. I have to at least try. But I expect you wont like it so ask JaKiri about Coulomb's Law of Electrostatic Attraction/Repulsion. Or Sayonara.