“The universe has been expanding since the big bang, thus early on it was hot and dense. To trace the history of the universe we must understand the dynamics that operates when the universe was hot and particles were very energetic. Before the standard model we could not go back further than 200,000 years after the big bang. Today, especially since QCD simplifies at high energy, we can extrapolate to very eary times, where nucleons melt and quarks and gluons are liberated to form a quark-gluon plasma.”

— David Gross

"The Discovery of Asymptotic Freedom and the Emergence of QCD" http://www.nobelprize.org/nobel_prizes/physics/laureates/2004/gross-lecture.html, Nobel Lecture, p. 79, nobelprize.org (2004)

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David Gross 6

American particle physicist and string theorist 1941

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“What the Big Bang theory tells us, is that at least our region of the universe 13.82 years ago, was an extremely hot, dense uniform soup of particles which in the conventional standard Big Bang model filled literally all of space—and now we certainly believe that it filled essentially all of the space that we have access to—uniformly. …This is contrary to a popular cartoon image of the Big Bang, which is just plain wrong. The cartoon image of the Big Bang is the image of a small egg of highly dense matter that then exploded and spewed out into empty space. That is not the scientific picture of the Big Bang. …If there was a small egg that exploded into empty space, you would certainly expect that today you would see something different if you were looking towards where the egg was, versus looking the opposite direction, but we don't see any effect like that. When we look around the sky the universe looks completely uniform, on average, in all directions, to a very high degree of accuracy… So we don't see a sign of an egg having happened anywhere. Rather, the Big Bang seems to have happened everywhere, uniformly.”

Alan Guth (1947) American theoretical physicist and cosmologist

Lecture 1: Inflationary Cosmology: Is Our Universe Part of a Multiverse? Part I.
The Early Universe (2012)

“Found that in a universe that is expanding after a big bang event, neutrinos would turn up at a detector before they were emitted. Only future-going neutrinos were possible in the Steady state cosmology while the ever-expanding big bang models gave neutrinos travelling into Steady State theory to the past.”

Jayant Narlikar (1938) Indian physicist

Neutrino misbehaviour suggested 50 years ago

“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 beginning, at least some precursor particle, if not the same particle, with no explanation of where all those particles came from.”

Alan Guth (1947) American theoretical physicist and cosmologist

Lecture 1: Inflationary Cosmology: Is Our Universe Part of a Multiverse? Part I.
The Early Universe (2012)

“That the universe, as was once thought, expands and contracts indefinitely, one Big Bang collapsing into another one, seemed reasonable enough. But in both models of the universe, what caused the first Big Bang? Or was there a first Big Bang, any more than a last number? If there was a first cause, was there a first causer? Did Big Bangs just happen to happen? Can we name the first causer “God”? We can name it anything we want. I can name it after myself. It is utterly insignificant what it is called, because we would be giving a name to something that falls outside all categories of thought and must be unknowable and irrelevant to knowledge. So naming it is a futile enterprise. The word “God” is unhelpful because it implies it has a knowable definition.”

Roger Ebert (1942–2013) American film critic, author, journalist, and TV presenter

Source: Life Itself : A Memoir (2011), Ch. 54 : How I Believe In God

“Around 13.8 billion years after the Big Bang, and almost four billion years since life first evolved, something strange began to happen: Tiny parts of the universe became conscious, and came to know something about themselves and the universe of which they are a part… Eventually, some of these tiny parts of the universe - the parts we call ‘scientists’ and ‘scientifically-informed laypeople’ - came to understand the Big Bang and the evolutionary process through which they had come to exist. After an eternity of unconsciousness, the universe now had some glimmering awareness that it existed and some understanding of where it had come from.”

Steve Stewart-Williams (1971)

Source: Darwin, God and the Meaning of Life: How Evolutionary Theory Undermines Everything You Think You Know (2010), p. 152

“…mention is made of evidences in favour of the big bang, like the microwave background. It is a relic radiation supposed to have formed very early after the big bang. As the universe expanded it cooled down and its present temperature is at 2.7 K. The only fact which is measurable or has been measured is that there is a background of 2.7 K temperature. Saying that this is left over from the early universe is a speculation. It is a part of a theoretical structure I am supposed to have built which enables me to say that it is a relic of that early-on era. We have given a different explanation. Helium forms by fusion of hydrogen inside a star like the sun, leading to radiation. One can ask the following question: if all the helium that you find in the universe was formed in stars sometime or the other, how much radiation will be formed and what would its temperature be? The answer is 2.7 K. If you ask a big bang person why his relic radiation today has a temperature of 2.7 K he doesn’t know. This alternative explanation that I’m giving is able to do more than what the big bang does. So I don’t see any reason to say we have a very positive proof of the big bang happening.”

Jayant Narlikar (1938) Indian physicist

Jayant Narlikar's Cosmology

“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 just the beginning of our local universe, often called a pocket universe.”

Alan Guth (1947) American theoretical physicist and cosmologist

Lecture 1: Inflationary Cosmology: Is Our Universe Part of a Multiverse? Part I.
The Early Universe (2012)

“By looking far out into space we are also looking far back into time, back toward the horizon of the universe, back toward the epoch of the Big Bang.”

Carl Sagan book Cosmos

Source: Cosmos

“Some people think that the big bang is an explanation of how the universe began, its not. The big bang is a theory of how the universe evolved from a split second after whatever brought it into existence.”

Brian Greene (1963) American physicist

In response to David Letterman's question, "What do we now know [about the universe] we didn’t know before?" on The Late Show (23 March 2005)
Context: Well, a big question is how did the universe begin. And we, cannot answer that question. Some people think that the big bang is an explanation of how the universe began, its not. The big bang is a theory of how the universe evolved from a split second after whatever brought it into existence. And the reason why we’ve been unable to look right back at time zero, to figure out how it really began; is that conflict between Einstein’s ideas of gravity and the laws of quantum physics. So, string theory may be able to — it hasn’t yet; we’re working on it today — feverishly. It may be able to answer the question, how did the universe begin. And I don’t know how it’ll affect your everyday life, but to me, if we really had a sense of how the universe really began, I think that would, really, alert us to our place in the cosmos in a deep way.

“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.”

Alan Guth (1947) American theoretical physicist and cosmologist

Lecture 1: Inflationary Cosmology: Is Our Universe Part of a Multiverse? Part I.
The Early Universe (2012)

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