You'll have to be more specific than "a few seconds." The Standard Model describes the temperature at various time periods following the initial event, which rapidly falls with time. For example, this site from UC San Diego gives the following numbers:
TIME (Secs) TEMP (K = Degrees Kelvin)
10-43 1032 K 10-35 1027 K 10-12 1015 K 10-6 1013 K .01 1011 K 1 sec 1010 K 15 secs 3x109 K 3 min 109 K
...and so on. At the present time the universe has cooled to 2.7 Degrees K.
Posts: 1976 | Location: U.S. | Registered: 06-03-02
Professor,my source doesn't provide any precisions about those "seconds". Your source sounds good to me, although 6 years old, while mine is more recent.I don't know if the figure is just a "general one" or an accurate one.
10 billion = 1010, which would correspond to about one second after the Big Bang. This is corroborated by another website from the University of Tennessee here.
Posts: 1976 | Location: U.S. | Registered: 06-03-02
Mozart: You know I'm not saying that your source (of which I am restricted to reading the first two paragraphs) is wrong. It looks like a good basic explanation consistent with my post above. Taking a logarithmic view (as suggested by physical law) the temperature exponent, which is falling, is down to 10 at one second, 9½ at 15 seconds, and 9 at 180 secs (3 min). So at "several seconds" the temperature is still on the order of 1010 degrees, i.e., that's the nearest power of 10.
As an aside: What if we use Fahrenheit or Celsius degrees instead of Kelvins? It doesn't matter! At billions of degrees an error of 273 is trivial, and even a factor of 1.8 changes log temp by about 1/4 of a power of 10, also trivial in this context for casual descriptions.
If you browse the links and view the physical states of the universe in chronologic order, various successive "epochs" emerge, most of which last for only a tiny fraction of the first second. If you read the whole account in reverse, with time running backwards to zero, then you see how particles behave at hotter and hotter temperatures, that is, at higher and higher energies, which in some ways reads as a history of high-energy physics research over the decades, using ever more powerful particle accelerators to learn about hotter and hotter conditions, making it possible to generate a table such as I posted.
Thus observations in accelerator labs, along with good theoretical models to interpret these observations, have allowed physicists to infer mathematically what the universe was like at earlier and earlier times after the Big Bang (BB). As is typical of a logarithmic scale, you can never arrive at time zero -- just shorter and shorter times before the BB.
Even the durable Standard Model eventually hits a brick wall where observations are plainly out of reach, such as with string theories involving tiny hidden dimensions. There is still considerable mystery and speculation surrounding the infinite singularity that lies at exactly time zero, if indeed that's what occurred (in some versions it's a "big bounce" where a crunch becomes a bang in finite time, and there are plenty of wilder scenarios).
At any rate, physicists are confident that several hundred thousand years after the BB (not shown in my little table) came a significant transition: the universe cooled off enough to form neutral gas from charged plasma, thereby becoming transparent to light for the first time. And it was good.
[Oops -- I accidentally overwrote my previous post, the risqué Johnny Carson joke. Freud says there are no mistakes... ]
This message has been edited. Last edited by: Professor,
Posts: 1976 | Location: U.S. | Registered: 06-03-02
And it was good. 
