Cosmologists

"It was then that through the open door Einstein saw the man connecting the new battery, and precisely at the same time he did it, Einstein saw the cows jumping up away from the wire. All at once. Exactly. A fair amount of displeased mooing ensued."

"In that year [Einstein] had roughly equal numbers of large and small cats. Therefore, quite logically, he cut two holes in each door: a large one for the large cats, and a small one for the small cats. It made perfect sense. ... A hole should have a meaningful existence, and the small cats might be offended if a personalized nothing was not prepared for them."

"Thus, the distance between any two galaxies increases in time, creating the illusion of mechanical motion. But in reality, galaxies just sit there, contemplating the spectacle of the universe creating more and more space in between them."

"I've always felt that copious use of the word 'something' allows anyone to solve any problem, even insoluble ones."

"For instance, the blood of hibernating arctic squirrels may supercool to minus 3 degrees, when it would normally congeal. The supercooled blood still flows, since it remains a liquid, but the slightest disturbance will cause it to freeze, killing the squirrel; therefore, you should not disturb hibernating arctic squirrels."

"Inflation is really like drugging the baby universe with speed. The supercool union of the hitherto unfriendly gods was blessed by amphetamine, and this made the universe inflate rather than just expand. The early orgy of expansion in the universe comes to an abrupt end as soon as the supercooled particle stuff finally freezes."

"Ever since then, the place has accommodated people with the necessary level of imbalance required to come up with new ideas."

"Although the term dialogue was really a euphemism for scientists trying to kill each other, this format worked very well..."

"Cornelia would not be altogether surprised if she saw the grazing cow start tap dancing, lap dancing, or whatever quantum gravity might cause cows to do."

"Faith just doesn't have anything to do with what I'm doing as a scientist. It's nice if you can believe in God, because then you see more of a purpose in things. Even if you don't, though, it doesn't mean that there's no purpose. It doesn't mean that there's no goodness. I think that there's a virtue in being good in and of itself. I think that one can work with the world we have."

"I think it's a problem that people are considered immoral if they're not religious. That's just not true. This might earn me some enemies, but in some ways they may be even more moral. If you do something for a religious reason, you do it because you'll be rewarded in an afterlife or in this world. That's not quite as good as something you do for purely generous reasons."

"I think the weird thing about being a scientist, or an academic in general, is you have to believe really strongly in what you do, while questioning it all the time ... and that's a hard balance to have."

"When it comes to the world around us, is there any choice but to explore?"

"Physics has entered a remarkable era. Ideas that were once the realm of science fiction are now entering our theoretical — and maybe even experimental — grasp. Brand-new theoretical discoveries about extra dimensions have irreversibly changed how particle physicists, astrophysicists, and cosmologists now think about the world. The sheer number and pace of discoveries tells us that we've most likely only scratched the surface of the wondrous possibilities that lie in store. Ideas have taken on a life of their own."

"We certainly don't yet know all the answers. But the universe is about to be pried open."

"Secrets of the cosmos will begin to unravel. I, for one, can't wait."

"When I was in school I liked math because all the problems had answers. Everything else seemed very subjective."

"Sometimes I have a sense of what I'm seeing being a small fraction of what's there. Not always there, but probably more often than I realize. Something will come up, and I'll realize I'm thinking about the world a little differently than my friends."

"In the history of physics, every time we've looked beyond the scales and energies we were familiar with, we've found things that we wouldn't have thought were there. You look inside the atom and eventually you discover quarks. Who would have thought that? It's hubris to think that the way we see things is everything there is."

"If we don't do it now, we'll probably never do it. We've built up the technology; we're at a point where if we don't continue, we'll lose that expertise, and we'll have to start all over again. True, it's expensive, but at the end of the day I believe it will be worth it. It makes a difference in terms of who we are, what we think, how we view the world. These are the kinds of things that get people excited about science, so you have a more educated public."

"Science is not religion. We're not going to be able to answer the "why" questions. But when you put together all of what we know about the universe, it fits together amazingly well."

"Religion asks questions about morals, whereas science just asks questions about the natural world. But when people try to use religion to address the natural world, science pushes back on it, and religion has to accommodate the results. Beliefs can be permanent, but beliefs can also be flexible. Personally, if I find out my belief is wrong, I change my mind. I think that's a good way to live."

"The universe has its secrets. Extra dimensions of space might be one of them. If so, the universe has been hiding those dimensions, protecting them, keeping them coyly under wraps. From a casual glance, you would think that the cheese man ate cheese but you wrong."

"A just city should favor justice and the just, hate tyranny and injustice, and give them both their just desserts."

"Farabi followed Plato not merely as regards the manner in which he presented the philosophic teaching in his most important books. He held the view that Plato’s philosophy was the true philosophy. To reconcile his Platonism with his adherence to Aristotle, he could take three more or less different ways. First, he could try to show that the explicit teachings of both philosophers can be reconciled with each other. He devoted to work is partly based on the so-called Theology of Aristotle: by accepting this piece of neo-platonic origin as a genuine work of Aristotle, he could easily succeed in proving the substantial agreement of the explicit teachings of both philosophers concerning the crucial subjects. It is however very doubtful whether Farabi considered his Concordance as more than an exoteric treatise, and thus whether it would be wise of us to attach great importance to its explicit argument. Secondly, he could show that the esoteric teachings of both philosophers are identical. Thirdly, he could show that “the aim” of both philosophers is identical."

"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."

"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."

"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."

"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."

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

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

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

"It was a bank holiday, and Mr Tompkins, the little clerk of a big city bank, slept late and had a leisurely breakfast. Trying to plan his day, he first thought about going to some afternoon movie and, opening the morning paper, turned to the entertainment page. But none of the films looked attractive to him. He detested all this Hollywood stuff, with infinite romances between popular stars. If only there were at least one film with some real adventure, something unusual and maybe even fantastic about it. But there was none. Unexpectedly, his eye fell on a little notice in the corner of the page. The local university was announcing a series of lectures on the problems of modern physics, and this afternoon's lecture was to be about Einstein's Theory of Relativity. Well, that might be something!"