Physicists From The United States

"Leon is a giant in our field in particle physics. ... he was an all-around approachable person. ... he had an open-door policy. ..."

"... I said I am doing experiments on pions. Einstein said, "Pions! Pions! We don't understand the electron. Why do you bother with pions? ...""

"The main virtue of the physics-chemistry-biology sequence is the hierarchical nature of the sciences. Physics comes first because it serves as a powerul prerequisite for chemistry and because it can more clearly illustrate the nature of the scientific process."

"Particle physics suffers more from being infected by the socio-political mood of the day than from lack of spectacular opportunities for major and profound discoveries."

"What the Big Bang theory tells us, is that at least our region of the universe 13.82 billion 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."

"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."

"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."

"It becomes very tempting to ask whether, in principle, it's possible to create a universe in the laboratory—or a universe in your backyard—by man-made processes."

"It is said that there’s no such thing as a free lunch. But the universe is the ultimate free lunch."

"The recent developments in cosmology strongly suggest that the universe may be the ultimate free lunch."

"It was fortunate that Alan Guth did his work at the same time that another idea came into fashion, which was the theory that we could understand why the universe contains matter and not antimatter in terms of some asymmetry, some favoritism for matter over antimatter in the early universe; it's no good having a scheme that can inflate the universe to enormous dimension of it's not possible to create matter to fill that large universe."

"One of the issues with the then generally accepted theory of the Big Bang was the uniformity of temperature measured in any direction out in the universe, no explosion on Earth could occur as uniformly. In the early 1980's Alan Guth postulated that the universe initially grew from a small enough volume, a fraction of the size of an atom, for temperature to have equalized, within its first billionth of a second of age, to then expand exponentially..."

"Prior to the downfall of the GUT in the mid 1980s, Alan Guth, an elementary particle theorist, was trying to explain the scarcity of the magnetic monopoles in the universe. The standard cosmological model predicted that there should be as many monopoles as there are nucleons! Since all attempts at finding a monopole had failed, Guth suggested that the universe must have had an inflation phase during which it expanded exponentially. This exponential growth was so rapid that it diluted any existing monopoles so much so that today there may be only a few in our observable universe."

"According to Guth, he had discovered the equations of De Sitter's cosmology (1917), written in the form introduced somewhat later by Georges Lemaitre (1925), as part of his MIT Thesis, before introducing inflation as the starting point of his new cosmology. After taking care, by means of inflation of the "monopole problem". ...Guth went one step further to solve the so called "flatness problem". ...Guth finally goes on to explain how his theory of inflation solves the "horizon problem". ...we will analyze in some detail to what extent the "monopole problem", the "flatness problem" and the "horizon problem" require, or not, cosmic inflation as a problem solving "paradigm"."

"We now address two of the drawbacks [of the standard Big Bang theory]... the flatness problem and the horizon problem. In the early 1980's, Alan Guth resolved these two problems with his inflationary theory. His basic idea was that the universe enters a false vacuum state shortly after the Big Bang, then tunnels out and expands exponentially. We choose to discuss Guth's original model (now called classical model or old inflation) for pedagogic reasons. Guth's model has many nice qualitative features; it does not work quantitatively. Therefore, A. Linde, A. Albrecht, P. Steinhardt, and others constructed new models as remedies. It is not clear which of the new models is correct..."

"Most of what we know, or believe we know, about the early moments of the universe is thanks to an idea called inflation theory first propounded in 1979 by a junior particle physicist, then at Stanford, now at MIT, named Alan Guth. He was thirty-two years old and, by his own admission, had never done anything much before. He would probably never have had his great theory except that he happened to attend a lecture on the Big Bang given by none other than Robert Dicke. The lecture inspired Guth to take an interest in cosmology, and in particular in the birth of the universe."

"The discovery of the CMB cemented the notion of a big bang. But for all its elegance, the theory had thrown up some intractable problems. Soon after the CMB was discovered, Dicke went to Cornell to talk about... the flatness problem. ...the universe seemed to be flat, meaning that the ratio of actual matter density to the critical density... Omega, was very close to 1. And for today's universe to have Omega anywhere near 1, its value just one second after the big bang had to be exactly 1 to a precision of about fourteen decimal places. Nothing in the laws of physics suggested why... In Dicke's audience was a young postdoc named Alan Guth. He was a particle physicist who had no interest in cosmology. But something about the talk tickled his fancy and set him on a journey that would solve the big-bang theory's most frustrating problem."

"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."

"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 electromagnetic interactions into a single unified interaction. ..we're talking about energies which are about 1016 times the equivalent energy of a proton mass. ...the initial patch would only have to be the ridiculously small size of about 10-28 cm across to be able to lead ultimately to the creation of everything that we see on the vast scale of which we see it."

"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."

"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."

"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."

"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.."

"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."

"In short what I like to say is that the Big Bang says nothing about what banged, why it banged, or what happened before it banged. It really has no bang in the Big Bang. It is a bangless theory, despite its name."

"The Big Bang theory says nothing about what banged, why it banged, or what happened before it banged."

"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."

"The conventional Big Bang theory does not say anything about what caused the expansion. It really is only a theory about the aftermath of a bang. In the scientific version of the Big Bang, the universe starts with everything already expanding, with no explanation of how that expansion started... So the Scientific version of the Big Bang theory is not really a theory of a bang, it's really a theory of the aftermath of a bang."

"If you take a bale of hay and tie it to the tail of a mule and then strike a match and set the bale of hay on fire, and if you then compare the energy expended shortly thereafter by the mule with the energy expended by yourself in the striking of the match, you will understand the concept of amplification."

"I had one experience which gave me some slant on the way large organizations run. I was not allowed to take spherical trigonometry because I'd sprained my ankle. Because I'd sprained my ankle I had an incomplete in gym, phys ed. And the rule was that if you had an incomplete in anything, you were not allowed to take an overload. I argued with some clerical person in the administration office, and was stopped there. It's an experience which I've remembered since, and advised people not to be stopped at the first point."

"Nature has color-coded groups of individuals so that statistically reliable predictions of their adaptability to intellectual rewarding and effective lives can easily be made and profitably used by the pragmatic man-in-the street."

"I am overwhelmed by an irresistible temptation to do my climb by moonlight and unroped. This is contrary to all my rock climbing teaching & does not mean poor training, but only a strong-headedness."

"My research leads me inescapably to the opinion that the major cause of the American Negro's intellectual and social deficits is hereditary and racial genetic in origin and thus not remediable to a major degree by practical improvements in environment."

"Today the network of relationships linking the human race to itself and to the rest of the biosphere is so complex that all aspects affect all others to an extraordinary degree. Someone should be studying the whole system, however crudely that has to be done, because no gluing together of partial studies of a complex nonlinear system can give a good idea of the behaviour of the whole."

"Possibly we will find an elegant model, in agreement with observation, that yields the pattern of lepton masses as well as the pattern of quark bare masses and even relates hadrons and leptons. This is our dream; touch us!"

"That which is not forbidden is mandatory."

"The Feynman [Problem-Solving] Algorithm: (1) Write down the problem. (2) Think real hard. (3) Write down the solution."

"Briefly stated, the Gell-Mann Amnesia effect works as follows. You open the newspaper to an article on some subject you know well. In Murray’s case, physics. In mine, show business. You read the article and see the journalist has absolutely no understanding of either the facts or the issues. Often, the article is so wrong it actually presents the story backward-reversing cause and effect. I call these the “wet streets cause rain” stories. Paper’s full of them. In any case, you read with exasperation or amusement the multiple errors in a story-and then turn the page to national or international affairs, and read with renewed interest as if the rest of the newspaper was somehow more accurate about far-off Palestine than it was about the story you just read. You turn the page, and forget what you know."

"One of the things that makes Gell-Mann so insufferable is that he is almost always right."

"I had barely sat down when he began to tell me... that science writers were "ignoramuses" and a "terrible breed" who invariably got things wrong: only scientists were really qualified to present their work to the masses. As time went on, I felt less offended, since it became clear that Gell-Mann held most of his scientific colleagues in contempt as well."

"The false report that measuring one of the photons immediately affects the other leads to all sorts of unfortunate conclusions. ...the alleged effect ...would violate the requirement of relativity theory that no signal... can travel faster than the speed of light. If it were to do so, it would appear to observers in some states of motion that the signal were traveling backward in time."

"The principal distortion disseminated ... is the implication, or even the explicit claim, that measuring the polarization, circular or plane, of one of the EPRB] photons somehow affects the other photon. In fact, the measurement does not cause any physical effect to propagate from one photon to the other. ...If on one branch of history, the plane polarization of one photon is measured and thereby specified with certainty, then on the same branch of history the circular polarization of the other photon is also specified with certainty. On a different branch of history the circular polarization of one of the photons may be measured, in which case the circular polarization of both photons is specified with certainty. On each branch, the situation is like that of Bertlmann's socks, described by John Bell... Bertlmann... always wears one pink and one green sock. If you see just one... you know immediately the other... Yet no signal is propogated... Likewise no signal passes from one photon to the other in the experiment that confirms quantum mechanics. No action at a distance takes place."

"While many questions about quantum mechanics are still not fully resolved, there is no point in introducing needless mystification where in fact no problem exists. Yet a great deal of recent writing about quantum mechanics has done just that."

"Niels Bohr brain-washed a whole generation of physicists into believing that the problem had been solved fifty years ago [Gell-Mann's comment on the Copenhagen interpretation]"

"If I have seen further than others, it is because I am surrounded by dwarfs."

"You don't need something more to get something more. That's what emergence means. Life can emerge from physics and chemistry plus a lot of accidents. The human mind can arise from neurobiology and a lot of accidents, the way the chemical bond arises from physics and certain accidents. Doesn't diminish the importance of these subjects to know they follow from more fundamental things plus accidents."

"Three principles — the conformability of nature to herself, the applicability of the criterion of simplicity, and the "unreasonable effectiveness" of certain parts of mathematics in describing physical reality — are thus consequences of the underlying law of the elementary particles and their interactions. Those three principles need not be assumed as separate metaphysical postulates. Instead, they are emergent properties of the fundamental laws of physics."

"Just because things get a little dingy at the subatomic level doesn't mean all bets are off."

"I thought of killing myself but soon decided that I could always try MIT and then kill myself later if it was that bad but that I couldn't commit suicide and then try MIT afterwards. The two operations, suicide and going to MIT, don't commute..."

"[Duesberg] is absolutely correct in saying that no one has proven that AIDS is caused by the AIDS virus. And he is absolutely correct that the virus cultured in the laboratory may not be the cause of AIDS."