“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 general relativity with conventional ideas, now, in particle physics there really is a pretty clear indication, I should say, not quite a prediction… that at very high energy densities one expects to find states of matter which literally turn gravity on its head and cause gravity to become repulsive.”

— Alan Guth

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

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Alan Guth 17

American theoretical physicist and cosmologist 1947

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“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 repulsively. Einstein introduced this in 1916… in the form of the cosmological constant, and the original motivation of modifying the equations of general relativity to allow this was because Einstein thought that the universe was static, and he realized that ordinary gravity would cause the universe to collapse if it was static. …The fact that general relativity can support this gravitational repulsion, still being consistent with all the principles that general relativity incorporates, is the important thing which Einstein himself did discover..”

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)

“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)

“A positive pressure produces an attractive gravitational field… Positive pressures are just sort of normal pressures and attractive gravity is normal gravity, so normal pressures produce normal gravity, but it is possible to have negative pressures, and negative pressures produce repulsive gravity, and that's the secret of what makes inflation possible.”

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)

“The gravitational repulsion created by this small patch of repulsive gravity material would be, then, the driving force of the Big Bang and it would cause the region to undergo exponential expansion… there is a certain doubling time, and if you wait the same amount of time it doubles again, and if you wait the same amount of time it doubles again… and it's because these doublings build up so dramatically, it doesn't take very much time to build the whole universe. In about 100 doublings this tiny patch of 10-28 cm can become large enough, not to be the universe, but to be a small marble-sized region which will then ultimately become the observed universe, as it continues to coast outward after inflation ends.”

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)

“When two identical 3He atoms collide… the interference is destructive. Particles that behave like 3He atoms are called fermions, short for "particles obeying Fermi–Dirac statistics."… while bosons imitate one another… the "identity force" between fermions acts like a repulsion, and the probability of finding a fermion at some point in space is reduced if some of its identical siblings are nearby…. It is the repulsive identity forces between electrons that support white dwarf stars… against their own gravity.”

Frank Wilczek (1951) physicist

Longing for the Harmonies: Themes and Variations from Modern Physics (1987)

“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 Newtonian physics, where it's only mass densities that produce gravitational fields.”

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)

“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 energy of matter goes upward by an enormous amount. Meanwhile, however, the energy of gravity becomes more and more negative. The negative gravitational energy cancels the energy in matter, so the total energy of the system remains whatever it was when inflation started—presumably something very small. …This capability for producing matter in the universe is one crucial difference between the inflationary model and the previous model.”

Alan Guth (1947) American theoretical physicist and cosmologist

"A Universe in Your Backyard," in Third Culture: Beyond the Scientific Revolution (1996) ed. John Brockman, p. 279.

“Laws never become theories! The theory of gravity includes a number of Newtonian laws. There is not one law of gravity; there are several laws included within the theory. The same goes for Relativity and even for evolution for that matter.”

Aron Ra (1962) Aron Ra is an atheist activist and the host of the Ra-Men Podcast

Patheos, Orwellian Legislative Duplicity on HB 1485 http://www.patheos.com/blogs/reasonadvocates/2017/05/05/orwellian-legislative-duplicity-hb-1485/ (May 5, 2017)

“Combine general relativity and quantum theory into a single theory that can claim to be the complete theory of nature. This is called the problem of quantum gravity.”

Lee Smolin (1955) American cosmologist

The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next (2007)

“Inflation is a simple idea: imagine that the universe begins in a tiny patch of space dominated by the potential energy of some scalar field, a kind of super-dense dark energy. This causes that patch to expand at a terrifically accelerated rate, smoothing out the density and diluting away any unwanted relics. Eventually the scalar field decays into ordinary matter and radiation, reheating the universe into a conventional Big Bang state, after which things proceed as normal.”

Sean Carroll (1966) American theoretical cosmologist

[The Eternally Existing, Self-reproducing, Frequently Puzzling Inflationary Universe, Preposterous Universe blog, 21 October 2011, http://www.preposterousuniverse.com/blog/2011/10/21/the-eternally-existing-self-reproducing-frequently-puzzling-inflationary-universe/]

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Alan Guth 17

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