Martin Posted June 19, 2004 Share Posted June 19, 2004 most of the galaxies that we will ever be able to see with our telescopes are receding from us at FTL speeds and indeed were recedingfrom us FTL when they emitted the light that we are now receiving from them and Einstein's theory of special relativity does not contradict this because it has nothing to say about recession speeds (the rates at which distances are increasing) but only about speeds of local encounter but some people dont realize this and assume that the galaxies we are looking at cannot be receding from us FTL and they may also think the redshift is a doppler effect which you learn already in basic introductory astronomy courses it is not (a careful distinction is made between cosmological redshift and doppler shift) also think about this: the universe is full of CMB photons which have experienced a redshift of 1100 that is, each photon has lost 1100/1101 of its energy---it has lost over 99 percent of its original energy from the 'recombination' era when those photons originated where has this huge amount of energy gone? is there a global energy conservation rule in Gen Rel that says it has to have gone somewhere? probably several people at SFN are equipped to discuss this, fafalone's profile says he's interested in cosmology and my guess is a bunch more are too and these are basic cosmology topics Link to comment Share on other sites More sharing options...
Martin Posted June 19, 2004 Author Share Posted June 19, 2004 As for most recession speeds being FTL put redshift z = 2 into the calculator here http://www.scienceforums.net/forums/showthread.php?p=56565#post56565 to set things up you first need to put 0.27 for matter and 0.73 for dark energy and 71 for the hubble parameter, which are standard cosmology estimates. galaxies as distant as z =10 have been observed, so way more are out there with z > 2 than are with z < 2 that is why it is typical or normal for a galaxy in the observable part of the universe to have redshift z > 2 so accordingly it is normal for them to be receding FTL Link to comment Share on other sites More sharing options...
TheProphet Posted July 3, 2004 Share Posted July 3, 2004 Lost energy? As far as i know light can't lose it's energy! Altough in this situation it will lose it's intensity! But not it's energy level. Or well the CMB:s total energy level raminas the same! But CMB level per Space is lower due to the strectching of space! So then the energy hasn't been lost, just streched as well... Link to comment Share on other sites More sharing options...
Martin Posted July 3, 2004 Author Share Posted July 3, 2004 Lost energy? As far as i know light can't lose it's energy! Altough in this situation it will lose it's intensity! But not it's energy level. Or will the CMB's total energy level remain the same! But CMB level per Space is lower due to the strectching of space! So then the energy hasn't been lost, just streched as well... I will try to direct you to a standard cosmology FAQ maybe Ned Wright's cosmology tutorial FAQ will work for you http://www.astro.ucla.edu/~wright/cosmolog.htm http://www.astro.ucla.edu/~wright/cosmology_faq.html he teaches the undergrad and graduate level courses in cosmology at UCLA and is also one of the team in charge of the WMAP satellite observing the CMB You are mistaken. Light can lose its energy. there is no global energy conservation law in General Relativity. the expansion of space has two effects: one (which you pointed out) is that there are fewer photons per cubic kilometer-----they get spread out into a larger volume the other is that an individual photon loses energy as its wavelength gets stretched out the energy of a CMB photon is hc/lambda where h is Planck constant and lambda is the wavelength-----stretching out the wavelength reduces the photon's energy roughly speaking: each CMB photon has individually lost 1100/1101 of its energy since the time when they were all last scattered besides which, since space has expanded by a factor of 1100 a sample volume has expanded by a factor of (1100)3 so CMB energy-per-volume has declined by a factor of (1100)4 this fourth power relation is a standard fact you get taught in an introductory cosmology course or will find referred to in pedagogical articles it is surprising the density of matter only goes down as the cube but the energy density of radiation falls off as the fourth power Try this article by Lineweaver (he was one of the team in charge of COBE an earlier CMB satellite observatory) Inflation and the Cosmic Microwave Background http://nedwww.ipac.caltech.edu/level5/March03/Lineweaver/Lineweaver_contents.html http://arxiv.org/astro-ph/0305179 the second link has a PDF version that is more readable but takes more time to download this essay of Lineweaver has been made into a chapter of a new book now in press called "The New Cosmology" (world scientific 2004) here's the part of my post I believe you were responding to: ---quote--- also think about this: the universe is full of CMB photons which have experienced a redshift of 1100 that is, each photon has lost 1100/1101 of its energy---it has lost over 99 percent of its original energy from the 'recombination' era when those photons originated where has this huge amount of energy gone? is there a global energy conservation rule in Gen Rel that says it has to have gone somewhere? ---end quote--- Link to comment Share on other sites More sharing options...
TheProphet Posted July 3, 2004 Share Posted July 3, 2004 Martin: I'll take my time tomorow and read upp on that.. Sounds really interesting, since i didn't tought it was possible. This opens also upp new scenarios, in my mind =) Thanks for the links =) Link to comment Share on other sites More sharing options...
TheProphet Posted July 5, 2004 Share Posted July 5, 2004 roughly speaking: each CMB photon has individually lost 1100/1101 of its energy since the time when they were all last scattered besides which' date=' since space has expanded by a factor of 1100 a sample volume has expanded by a factor of (1100)[sup']3[/sup] so CMB energy-per-volume has declined by a factor of (1100)4 this fourth power relation is a standard fact you get taught in an introductory cosmology course or will find referred to in pedagogical articles it is surprising the density of matter only goes down as the cube but the energy density of radiation falls off as the fourth power Well this is very interesting! To me it almost lokes like if Radiation is downsizing in 4 dims and matter in 3... Which again mess mu head upp.. This really calls for the "thinker hat"! here's the part of my post I believe you were responding to: ---quote--- also think about this: the universe is full of CMB photons which have experienced a redshift of 1100 that is' date=' each photon has lost 1100/1101 of its energy---it has lost over 99 percent of its original energy from the 'recombination' era when those photons originated where has this huge amount of energy gone? is there a global energy conservation rule in Gen Rel that says it has to have gone somewhere? ---end quote---[/quote'] Even more interesting, also since my belif where contradicted. Something somehere must have taken upp the energy (logicly). Well guess we need to disect GR.. then.. Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 our eleven dimensions cancel out the tachyon frequencies. tachyons dont exist. nothing can go faster than the speed of light (light in a vacum) Link to comment Share on other sites More sharing options...
Sayonara Posted July 6, 2004 Share Posted July 6, 2004 our eleven dimensions cancel out the tachyon frequencies. Evidence? Or at the very least, reasoning? tachyons dont exist. Santa position. Lack of evidence for is not evidence against. nothing can go faster than the speed of light (light in a vacum) Except tachyons, which don't have a positive or zero rest mass. Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 it is math. the eleven dimesnsions cancel out the tachyon frequencies, therefore they do not exist Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 IF tachyons existed, they would have imaginary mass. how can something have imaginary mass? Link to comment Share on other sites More sharing options...
Cap'n Refsmmat Posted July 6, 2004 Share Posted July 6, 2004 it is math. the eleven dimesnsions cancel out the tachyon frequencies, therefore they do not exist And how is that? Can you be sure there are eleven dimensions? Link to comment Share on other sites More sharing options...
TheProphet Posted July 6, 2004 Share Posted July 6, 2004 Imaginary Mass is just as real as 11 Dimensions and your evidences.... for the moment... FTL recesions speed is Space movin.. not any particle.. so it's highly possible, and also hace evidence form measurments... Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 how can imaginary mass be real? it is like negative distance (point A is closer to point B than point B is to itself) Link to comment Share on other sites More sharing options...
TheProphet Posted July 6, 2004 Share Posted July 6, 2004 How can 11 dimensions be.. At the moment we know jsut as little about both.. gues we know more of imaginary math though... Link to comment Share on other sites More sharing options...
Sayonara Posted July 6, 2004 Share Posted July 6, 2004 how can imaginary mass be real? it is like negative distance (point A is closer to point B than point B is to itself) Not the best example, as distance relies on available routes. Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 oops i accidently made a pun, sorry "how can imaginary mass be real" lol Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 for the eleven dimensions we invoke the mighty powers of calibi-yau manifolds Link to comment Share on other sites More sharing options...
TheProphet Posted July 6, 2004 Share Posted July 6, 2004 Well Calabi-yau:s look very nice on papper.. but there are more theories! And as far as i'm concerned String theory have huge troubles, when other fields make big stepes forward... Ad don't forget that it's M theory that gives u 11 dimensions. Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 string theory is part of m-theory. m-theory combines all string theories into one Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 what is wrong with string theory? Link to comment Share on other sites More sharing options...
TheProphet Posted July 6, 2004 Share Posted July 6, 2004 Most of the math needed for String/M thoery haven't and even haven't been able to count(worked out.. hey im swedish ).. And also.. one even simpler thing is that String thoery gets more an more complex as it goes. Souns like they are trying too patch the theory togehter more and more with even more complexity.. and you should keep it as simple as possible (Which also Einstein said) Lots of other theorys seem to have equel or even bether chance to quantize Gravity.. Im not saying M/string thory is wrong.. no theory never really are! Still interesting but seem to get too complex to be true... but who knows. Altough u seem to have worked your faith out! Good for you Link to comment Share on other sites More sharing options...
JaKiri Posted July 6, 2004 Share Posted July 6, 2004 what is wrong with string theory? At the moment, it's about the same distance from a nobel prize in physics as 'Wouldn't it be nice if we could all get along' is from a nobel prize in peace. In the end reckoning, string theory hasn't predicted anything yet, and hasn't actually done anything yet. If it all (ever) gets worked out, it could be wonderful, but currently to base assumptions or predictions on it is foolish at best. Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 it WOULD have predicted the masses and acharges of elementary particles, but we already knew them. the properties found by string theory were correct Link to comment Share on other sites More sharing options...
JaKiri Posted July 6, 2004 Share Posted July 6, 2004 it WOULD have predicted the masses and acharges of elementary particles, but we already knew them. the properties found by string theory were correct That's a circular argument at best. Link to comment Share on other sites More sharing options...
ydoaPs Posted July 6, 2004 Share Posted July 6, 2004 what I meant was, if we had no knowledge of the properties of particles, then string teory would have predicted them Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now