“There was a young fellow from Trinity
Who took the square root of infinity
But the number of digits
Gave him the frights;
He dropped Math and took up Divinity.”
Ever come across this before?
This is one of the limericks that the ingenious George Gamow had sent to one of his friends. Gamow, was Russian-born American Nuclear Physicist and Cosmologist, a Cartoonist, a Jester and chiefly, famous for his books on advanced science (the only few that catered to the teenagers). Although he had a turbulent history, to say the least, he battled it out to fame when he solved the mystery of why radioactive decay was possible. He then hit it big when he discovered the nuclear reactions that gave birth to the lightest elements we see in the universe. He gave the theory of the “hot” initial state of the universe and on that basis, presumed that perhaps some of its “residual” heat is still circulating around the universe today. He called this uniform haze of radiation, Cosmic Microwave Background Radiation.
This was also the first time that someone had suggested that the radiation of the big bang might have a specific characteristic – black body radiation. Gamow and two of his Ph.D. students used this characteristic to calculate the temperature of the early days of the universe, to back-calculate its age. Although the temperature (5 degrees above absolute zero) left them disappointed (because such a low temperature would be very difficult to measure), unfazed, he continued to be the leading personality pushing the big bang theory.
Moreover, in his much celebrated paper, “Alpha-Beta-Gamma”, he put forward the idea that the entire Mendeleev periodic chart of chemical elements, could be created from the heat of the big bang. He explained this by suggesting that the heat of the big bang was sufficient for fusion to take place, leading to the formation of heavier elements from lighter ones, through subsequent collisions. Working this out the other way, this could be used as one of the “proofs” of the big bang theory.
However, there were problems with his calculations that he himself had figured out. This theory had worked well for light elements, but the same couldn’t be said about elements with 5 and 8 neutrons and protons (because they were extremely unstable). This posed a big problem that loomed over scientists quite some time. Additionally, it also doomed his vision of proving his theory.
Despite the inconsistent results of the theory, it was still the only plausible one in the picture. But what’s the fun in having a theory stand without opposure! Fred Hoyle, an English astronomer and cosmologist, disproved of the Big Bang Theory (ironically, he was the one to coin the term “Big Bang” during a show on the radio) and was the foremost proponent and defender of the steady-state theory of the universe. He had a reputation for his combative behaviour and was one of the few who stepped over the line to defy the now well-settled and widely accepted theory of the birth of the universe.
In his model, portions of the universe were expanding, yes, but new matter was being created out of nothing, to maintain the density of the universe at a constant. His universe had no end, no beginning. It just existed the way it was, timeless (although he couldn’t explain or give details about how this would happen, this was his only response to the “illogical” big bang theory).
He also incorporated in his theory, his belief that elements of the universe weren’t created in the big bang, but proposed that that happened at the centre of stars (because if all the elements were created in the immense heat of the stars, there was no need for the big bang at all!). Through papers that came after, Hoyle and his colleagues laid out details on how this would happen. Indeed, with a stroke of genius, Hoyle had realised that the answer was in the unstable form of carbon that had previously gone unnoticed. It was created by three helium nuclei and would last long enough to form a “bridge”.
When this form of carbon was actually found, it proved that nucelosynthesis could take place in the stars. More importantly, this allowed for higher elements to be created. But, even this tremendous amount of energy wasn’t enough to create elements beyond iron. For those heavier elements was needed, an even larger furnace, like supernovae. Hoyle published this work, along with steps to predict the respective abundances of these elements. His arguments were so powerful and persuasive, that even Gamow had to give in to accepting that his was the most compelling picture of nucelosynthesis given so far.
But things didn’t go on so well for Hoyle for too long. With the passage of time, came up evidence to disprove his theory on grounds of the static nature of the universe. Taking into account his theory, the present day universe should look exactly like it did billions of years ago (since his theory didn’t mention a “start” to the universe).But there were signs of dramatic changes in the universe (like quasars) and with this started the downfall of the probably the only theory that could stand up to the big bang theory for even this long.
Helium too became too “heavy” a problem for Hoyle’s theory to handle. According to the steady state theory, Helium was primarily created in stars. It should thus be rare in the empty space and should be found only near the cores of the stars. But scientists found that helium was actually pretty plentiful throughout.
Interestingly though, today we see that both Gamow and Hoyle both had some truth to their respective theories (concerning nucleogenesis). Like Gamow said, very light elements ( below the 5- and 8- particle gap) were formed in the big bang, while heavier elements (upto iron) were created in the cores of stars, as had proposed Hoyle, with heavier elements being cooked up in the blistering heat of the supernova.
Had it not been for the numerical error in Gamow’s calculations to come up with the wrong temperature, or for Hoyle’s aggressive nature towards the Big Bang Theory, history might have written itself differently.
Electrical and Electronics Engineering
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