Steven Weinberg, Higgins Professor of Physics, told a crowd of over 500 at the Science Center last night that "using the known laws of physics, it is possible to extrapolate backwards toward the beginning of the universe" to discover how it looked approximately 15 billion years ago.

"As we go further back in time, the universe gets increasingly hotter and denser," Weinberg told the overflow crowd in Science Center B.

"The finite moment of infinite density and heat, at time zero, is the origin of the universe," he said.

Speaking on the topic of his recently published book, "The First Three Minutes: A Modern View of the Origin of the Universe," Weinberg said that at its origin, the universe was composed solely of radiation and sub-atomic particles.

The formation of protons from these particles was accomplished extremely quickly, Weinberg said.

Cooling and expansion of the central core of energy occurred so rapidly, he said, that by 182 seconds after "time zero," the originally infinite temperature of the universe had cooled to 109 degrees Kelvin, and hydrogen and helium nuclei had formed.

"Other elements were formed on stars later from these building blocks" Weinberg added. "But is wasn't until the universe was about 700,00 years old that it was cool enough for atoms to form."

When asked what was present before the origin of the universe, Weinberg said, "The belief that there was anything before time zero is a common misapprehension of which I am sure physics will rid us someday."