Alan Guth

"A very plausible choice for when inflation might have happened would be when the energy scales of the universe were at the scale of grand unified theories... which unify the weak, strong and electroma…"

"It turns out that the energy of a gravitational field—any gravitational field—is negative. During inflation, as the universe gets bigger and bigger and more and more matter is created, the total energ…"

"We should not act like we know that the universe began with the Big Bang... we'll see that there are strong suggestions that the Big Bang was perhaps not really the beginning of existence, but really …"

"Inflation takes advantage of this possibility... to let gravity be the repulsive force that drove the universe into the period of expansion that we call the Big Bang. In fact, when one combines genera…"

"The miracle of physics that I'm talking about here is something that was actually known since the time of Einstein's general relativity; that gravity is not always attractive. Gravity can act repulsiv…"

"What it takes to produce a gravitational repulsion is a negative pressure. According to general relativity, it turns out... both pressures and energy densities can produce gravitational fields, unlike…"

"Inflation is a prequel to the conventional Big Bang theory. ...It does provide a theory of the propulsion that drove the universe into this humungous episode of expansion which we call the Big Bang."

"The conventional Big Bang theory says nothing about where all the matter came from. The theory really assumes that for every particle that we see in the universe today, there was, at the very beginnin…"