Expert: Jayendra Upadhye - 7/23/2008

Question
QUESTION: Hi again Jayendra,
I keep forgetting to give my Qualifiations. Here goes I studied physics at High School got a B in Higher Physics (Scottish exam), I was always in the A class for Mathematics. So I'm bright but did not study Science at University(I did Accountancy).
Anyway to my Question: You said CMB was the best evidence for big bang. I once watched a programme where scientists were trying to get to zero degrees Kelvin. They got near by using vacuum flasks. Anyway my point and yours was that 3 degree Kelvin is as cold as it gets in outer space(or anywhere without using flasks). So from this why isn't it slightly warmer e.g. 10 degrees or something above Kelvin, if the Universe was meant to be superhot 13.7billion years in the Past. To me 3 degrees Kelvin could mean that this is as cold as it gets and this is what it always has been forever. I.e the universe could be 100 billion yrs or 1million billion yrs or an unknowable amount of billions of years. So Why does CMB make the universe 13.7billion yrs old?

ANSWER: Hi,
That is why in fact the CMB was a very good proof of the bang!

The 3 degrees part was predicted much earlier!
And it was discovered to corroborate the prediction, only later, in the 1960s.
[The cosmic microwave background was predicted in 1948 by George Gamow and Ralph Alpher, and by Alpher and Robert Herman.]

If the bang happened at the temperatures required by astrophysics (thermodynamics actually), then at its current observed state of expansion, and based on the matter - energy decoupling event that happened quite a bit later after the bang, The current temperature of the expanded universe would be close to 3 degrees kelvin.

The CMB actually showed that was true.
It was a highly isotropic radiation coming from all directions of space (another propwerty of any radiations that shared the expansion of the universe from the earliest times, and hence which was a very ancient radiation indeed)!
Indeed the CMB is highly isotropic and this presented a big question, until the COBE found trace anisotropies that when calculated with the aggravating effect of gravity, lead to the current largescale structure of the universe.

Gravity is indeed an amplifier for anisotropies (disturbances in the matter distribution over space). It aggravates clumpiness.
13 billion years is time enough for it to convert "more or less" uniform plasma into a spongy mass of galaxies spanning huge voids.

Thermodynamics / black body concepts you need to understand if you want to grasp wha the reference below says.

The universe has been expanding "adiabatically" without loss of heat, because by definition, the universe contains all there is to contain! So any heat "lost" to another region by definition, is movement of heat within the universe only and not a loss "to something outside"!
That makes it a lossless adiabatic expansion, akin to a balloon expanding, but still containing all the gas inside it, and not allowing it to escape.

COBE found the anisotropies at 1 part in 100,000!!

A bang happening at 13 billion years ago, at temperatures expected, fi expanded adiabatically would have a black body radiation corresponding to 3 deg kelvin. And the CMB is at that temperature as predicted. What better proof could one have?

to quote,
[
"Two of the greatest successes of the big bang theory are its prediction of its almost perfect black body spectrum and its detailed prediction of the anisotropies in the cosmic microwave background. The recent Wilkinson Microwave Anisotropy Probe has precisely measured these anisotropies over the whole sky down to angular scales of 0.2 degrees. These can be used to estimate the parameters of the standard Lambda-CDM model of the big bang. Some information, such as the shape of the Universe, can be obtained straightforwardly from the cosmic microwave background, while others, such as the Hubble constant, are not constrained and must be inferred from other measurements."
]

The CDM is Cold Drak Matter.


refer:- http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation

Please do rate the answer as usual if you find it interesting.

Robert! Cease to be a doubting tom and become a seasoned trojan!
learn your "multiplication tables and arith" first before you seriously start questioning the "differential/integreal calculus" of astrophysics!! :)

regards
Jayen

---------- FOLLOW-UP ----------

QUESTION: Hi Jayen,this doesn't really answer why the universe is 13.7 bill yr old. If the universe was hot plasma 3000K with x m^3 volume it then expands to y m^3 volume , so adiabatically its 3K. This means you have 2 unknowns x and y to make things work. But it could never be 0 degree Kelvin for this atoms have to have no movement. So it could be a million times bigger and/or a million times older and still have a blackbody radiation of 3K. It could never be 0 Kelvin and why would it be higher than 3K?

ANSWER: Hi Robert!
You remind me of another question...how many times can one halve an a4 size paper sheet to reach the size of the atom?

Some say 16, some say 64...but in a finite number of halves, we reach the size of the "indivisible atom. One simply has to be "persistent" enough.

Likewise, one simply has to be "persistent enough", in asking questions to any "expert", before the poor guy "hits rock bottom"!!

My metaphorical "rock bottom" has been reached by you.

I cannot add anything further on this for you.

All i can do now is "point elswhere"!

And that "elsewhere" is to George Gamov, author of the excellent "The birth and death of the sun", that i had the chance to read when i was in my eighth class, in school.

That was the time i was doing a lot of trojan horsing...what with Tsialkovsky's "modern rocketry", Neville schute's "the breaking of the sound barrier" (or some thing like that about the bell x-1), loads of bound annual volumes of SATURDAY NIGHT REVIEV with wild stories of the Partisan's on horseback in the arabian desert beheading their opponents..(first time a read the word "squeamish")...and other annual volumes of "National geographic..(Read all about Auguste Piccard's stratosphere record and bathyspcape / bathysphere records too!

TRUST ME, the days of doubting science are over, one must rather doubt religion now. THAT requires more courage and honesty than doubting science. It has PROVEN ITSELF many times over, by predicting things in fine details only to have the corroborative evidence come out later.

cases:-
1 - The neutrino flash was a prediction of supernova theory, and was actually detected in case of SN1987A even as the main shock wave emerged a day or two later!

2 - The prediction that the SN1987A supernova debri should cause rings of fire when it overtook a previously shed shell of gas by the progenitor star, also turned out to be true, as hubble observed the flashes occuring two years after the main event.

3 - The very old prediction (chandrashekhar's limit) on the upper limit to the size of a white dwarf, still holds, as no white dwarf of higher size has been found till date.

4 - Ofcourse the CMB prediction by Gamov (5 degrees K).
He was off by only 2. something deg K!!

Try and read up the Actual theory of Gamov, his assumptions, his actual observations, and the underlying thermodynamics, and who knows in the process, you may yourself become what you chose to question!
(A yoga of sorts!!).


regards
Jayen

---------- FOLLOW-UP ----------

QUESTION: Hi Jayen, You seem a little upset. It is not my intention to demoralise you. I am only questioning big bang theory. I do not doubt the scientific method. Its simply the size of the universe at the 3000K stage with its current size at the 2.75 degree Kelvin temperature. Surely these 2 volumes have been approximated. Then I can work through the thermodynamics, which should be like the Hot Bath of water in the Bathroom which reach equilibrium as the water cools. Some of your other points I want to ask about later. Many Thanks Robert

Answer
Robert!
I thinkk i did not put it through succinctly enough.
I am not demoralised.
why should i be? :)
Indeed this is NOT the first time i have admitted to anyone that i do not know.

I am utterly shameless in admitting i do not know, that's all!

Like that paper example, your persistent questioning has brought you to the end of my knowledge on the subject!
That was what i was saying, that i had bottomed out, and you needed to go into Gamov's assumptions and his theory to understand how he could predict a temperature of 5 deg k.
[against an actual of 3].

In order to keep learning more, i have to remain "planted on the ground", by first understanding that i know less!

Simple enough dont you think?

And yes, i have "surrendered to science, scientefic temper" because all its work proceeds from questioning everything before accepting it.

Indeed there may be on the web many sites that actually go into the detail of the bang. (The first 3 minutes ..by hawking?) is another great source.

I am meanwhile trying to look it up myself, and see if i get any thing more on the subject.

Robert however you also need i think to look up black bodies and black body radiation, as teh CMB is such a radiation type.

Lastly, it IS NOT like a bath of hot water cooling!

It is much more complex than that.

1 - It starts off as a point
2 - then as a rapidly inflating volume at extremely high temperature
3 - then as a rapidly cooling body that is still all energy.
4 - then as an expanding body of hot plasma wherein localised anisotropies also create currents of moving matter following laws of magnetohydrodynamics.
5 - then after the energy matter decoupling, as a cooling body as  in a "cooling body of gas", following the gas laws and kinetic theory of gases.

which you will agree is a different cup of tea altogether than water in a tub.

That is why i said if you master that physics and maths, you might as well be Gamov!

regards
Jayen