Physicists From The United States

"Goudsmit stumbled to fame in 1925. For more than a decade, Niels Bohr and others had been trying to develop a quantum theory of the atom, mostly by studying atomic spectra. These consist of the energies (specific to each element) of the quanta of light, or photons, that an atom’s electrons can absorb or emit. Physicists had been struggling to make sense of anomalies that appeared in spectra when atoms were immersed in a magnetic field: some spectral levels mysteriously split into two or more. Goudsmit and his friend George Uhlenbeck, both graduate students at Leiden University in the Netherlands, had an idea. They proposed that the splitting could be explained if the electron had an intrinsic ‘spin’ that could assume one of two directions: clockwise or anticlockwise. Other physicists had discarded this idea, seeing it as marred by conceptual difficulties. ... Soon, researchers including Paul Dirac explained away the conceptual difficulties. Quantum spin was born."

"In his 1930 book, Dirac took for granted that measurements could be made, but was very vague about what was actually involved."

"Neither Dirac nor von Neumann discussed his measurements in physical terms."

"At the first of the 1960's Rochester Coherence Conferences, I suggested that a license be required for use of the word photon, and offered to give such license to properly qualified people."

"I liked quantum mechanics very much. The subject was hard to understand but easy to apply to a large number of interesting problems."

"In fact, there really is not a new law of nature. It was all in the theory to begin with but nobody worked it out."

"A rare theorist turned experimentalist."

"A gifted experimentalist, and theoretician, in the best Newtonian tradition... His contributions to quantum measurements, and elucidative teachings on quantum mechanics, have not yet received the attention they deserve."

"The best colleagues are those who will think about your ideas, who will talk with you and offer insight, constructive criticism. No one needs to be crushed for having a new idea."

"I always look for colleagues who are smart, and who know a lot in many fields. The obvious advantage is that he or she may be able to solve the problem that has produced trouble in your work. Also smart and knowledgeable colleagues can save you time, and are interesting and inspiring!"

"You may turn a bad idea into a good idea — don't kill the bad idea prematurely. A bad idea can evolve into a good idea."

"For every good idea, expect to have five, ten, twenty wrong or useless ideas. You cannot avoid the bad ideas if you keep your imagination free. There is no spam filter for bad ideas."

"Imagination and obsession are the keys to getting a good idea. To help your imagination keep your eyes and ears open. Avoid the "not invented here prejudice"."

"Common elements of creativity are originality and imagination. Creativity is intertwined with the freedom to design, to invent and to dream. In engineering and science a creative idea is useful only if it meets three conditions: the constraint of the natural laws, the constraint of cost, and the constraint of technical feasibility."

"It is always a good plan for a speculative experimenter to have two experiments going, or at least one going and one being built."

"Experimental science is a craft and an art, and part of the art is knowing when to end a fruitless experiment. There is a danger of becoming obsessed with a fruitless experiment even if it goes nowhere."

"The experimenter dealing with nature faces an outside and often hard world. Natures' curriculum cannot be changed."

"Ever since before quantum phenomena became definitely recognized many attempts were made to picture their mechanism."

"...the more accurate the calculations became, the more the concepts tended to vanish into thin air."

"Most of us have grown so blase about computer developments and capabilities — even some that are spectacular — that it is difficult to believe or imagine there was a time when we suffered the noisy, painstakingly slow, electromechanical devices that chomped away on punched cards."

"The national research effort, upon which so much depends, will remain healthy only so long as there is sound core of disinterested search for new knowledge and an adequate number of men and women trained for carrying on such research and for teaching young scientists."

"Effective science teaching calls for active contact with research and that teachers need to mingle with other scientists and to know what is going on in the field."

"Only by doing the best we can with the very best that an era offers, do we find the way to do better in the future."

"One of the most fertile and original men I have ever known. … He was a rare combination, almost unique, of a theoretical physicist and a thoroughly practical engineer."

"Good physics can be done if we have a good shop. … Given a good shop and good measurement equipment a sound physicist can do wonderful work."

"What can we sell them? Not our soul."

"There might be very primitive life in our solar system — single-cell animals, that sort of thing. We may know the answer to that in five or ten years. There is very likely to be life in other solar systems, in planets around other stars. But we won't know about that for a long time."

"When you're on Earth, if you go to the top of a mountain, the stars look much brighter than they do at sea level. And because the space shuttle is above Earth's atmosphere, it's like being on a very, very high mountain. So they look brighter, but not bigger."

"The view of Earth is spectacular. The shuttle is pretty close to Earth. It only flies between 200 and 350 miles above Earth. So it's really pretty close. So we don't see the whole planet, like the astronauts who went to the moon did. So we can see much more detail. We can see cities during the day and at night, and we can watch rivers dump sediment into the ocean, and see hurricanes form. It's just a lot of fun and very interesting to look out the window."

"It's easy to sleep floating around — it's very comfortable. But you have to be careful that you don't float into somebody or something!"

"It takes a few years to prepare for a space mission. It takes a couple of years just to get the background and knowledge that you need before you can go into detailed training for your mission. So most astronauts are astronauts for a couple of years before they are assigned to a flight. Once you are assigned to a flight, the whole crew is assigned at the same time, and then that crew trains together for a whole year to prepare for that flight."

"When you're getting ready to launch into space, you're sitting on a big explosion waiting to happen. So most astronauts getting ready to lift off are excited and very anxious and worried about that explosion — because if something goes wrong in the first seconds of launch, there's not very much you can do."

"It may also be pertinent to ask whether a greater effort in the less expensive basic stages of research may not lead to reductions of effort in the far costlier stages of development and prototype construction."

"Now, since the time of Newton there had been a debate about whether light was a wave---that is, a traveling disturbance in some background medium---or a particle, which travels regardless of the presence of a background medium. The observation of Maxwell that electromagnetic waves must exist and that their speed was identical to that of light ended the debate: light was an electromagnetic wave."

"My area of research is something that in all fairness has no practical usability whatsoever and the thing is I'm often asked to apologize for that. It is interesting to me that people ask 'what's the point of doing that if it's not useful?' But they never ask that, or do they very rarely ask that about art or literature or music. Those things are not gonna produce a better toaster."

"There is a maxim about the universe which I always tell my students: That which is not explicitly forbidden is guaranteed to occur."

"The problem of transmitting scientific knowledge is a very difficult business."

"The pretention that some of us are better than others, I don't think is a very good thing. And who is contributing what to our progress in science is not so obvious and many who don't get that Nobel Prize are better than people than some of us that do get the Nobel Prize. … I think we should not be interested in prizes, we should be interested in learning about nature."

"You only have one life. Whatever crops up, crops up."

"There's a loophole if you weigh galaxies and clusters because you're weighing the total amount of energy around galaxies. What if there's energy where galaxies aren't? What is where galaxies aren't? Nothing."

"[W]e can weigh systems of galaxies. The largest bound objects in the universe are called clusters of galaxies. They're maybe ten million light years across. ...We weigh them using gravity because Einstein told us that mass curves space, and we can... use those large clusters as lenses—if there's a light source behind a cluster the light from it can come around and be lensed... and we've weighed these systems and we've found that there's only 30% of the mass needed to make a flat universe... Theorists like me knew that the universe was flat, because it's the only mathematically beautiful universe... but here these observers kept coming up with only 30% of the stuff needed... But then, what we've discovered... is that the universe actually is flat and the rest of the 70% of the energy of the flat universe comes from the energy of nothing."

"[W]hy presumes purpose... But what if there isn't purpose? Whenever we say why we really mean how."

"[Y]ou... may say, "Well look, we've got no space, no time, no particles, no radiation. That's a pretty good approximation of nothing, but there's still the laws. Who created the laws? And... what we've discovered... in the last ten years or so, and... this is speculative, but it's based on everything we know of in particle physics... It's quite reasonable to suspect that even the laws themselves came into existence when our universe came into existence... There could be many different universes and in each one of them the laws of physics are different. They spontaneously arise when the universe arises."

"[W]hen you apply quantum mechanics to gravity, then even space itself can pop into existence from nothing. Space and time can spontaneously pop into existence... Whole universes can pop into existence and most of them will disappear in a time scale so short you wouldn't know about it. The ones that can survive for a long time have zero total energy..."

"Now some people say, "Well, if there's virtual particles there it's really not nothing," but there are no real particles. You try and measure things there, there's nothing, but those virtual particles can give space energy and in fact we've discovered to our great surprise—it won the Nobel prize two years ago—that empty space has energy, and if you put energy in empty space, then it's really strange because it's not like the normal energy... it's not gravitationally attractive, it's actually repulsive, and we've discovered the expansion of the universe is not slowing down like any sensible universe should do. It's actually speeding up... because it's dominated by the energy of empty space."

"[O]ne of the great things about science is it forces us to refine our idea of what's common sense. It forces us to have our beliefs conform to the evidence of reality rather than the other way around. The universe may not be like we'd like it to be, but it doesn't really care."

"The energy of every galaxy—all the galaxies are moving away from us at, Hubble discovered that in 1929... If you measure their speed and then you work our the attraction the two add up to precisely zero. An amazing discovery that confirms this notion that, not only is the universe flat and mathematically beautiful, but begins to give us an inkling that maybe, maybe, maybe we could come from nothing."

"But what we've discovered is that, in fact... the total energy of the universe could be zero, which is a first clue that maybe it could come from nothing. ...In physics, ...once you include gravity, there's positive energy and negative energy, and our universe appears as if its total energy could be precisely zero, which is the first hint that maybe it could come from nothing. That, and the great discovery... that namely empty space, you take a region of space, get rid of all the particles and all the radiation ...so there's nothing there. That empty space weighs something, and we don't understand why."

"Richard Feynman used to go up to people all the time and he'd say, "You won't believe what happened to me today. You won't believe what happened to me." And people would say "What?" And he'd say, "Absolutely nothing". Because we humans believe that everything that happens to us is special, and significant. And that—and... Carl Sagan wrote beautifully about that in Demon-Haunted World—that is much of the source of religion. OK? Everything that happens is unusual, and I expect that the likelihood that Richard and I ever would've met—if you think about all the variables, the probability that we were in the same place at the same time, ate breakfast at the same... Whatever. It's zero. Every event that happens has small probability... but it happens, and then when it happens; if it's weird, if you dream one million nights and it's nonsense, but one night you dream that your friend is gonna break his leg and the next day he breaks his arm. You think, "ah." ...So the [real] thing that physics tell us about the universe is it's big, rare events happen all the time—including life—and that doesn't mean it's special."

"What's going to happen in the far future? Remember a hundred years ago we thought we lived into static eternal Universe. What will the future bring? The amazing thing is, for civilizations that live in a far future, what will they see? Well, the Universe is accelerating. That means all the distant galaxies are getting carried away from us, and eventually they'll move away from us faster than the speed of light. It's allowed in General relativity. They will disappear. The longer we wait, the less we will see. In a hundred billion years any observers evolving on stars around [us]... and there will be stars just like our Sun in 100 billion years. Any observers and civilizations... evolving around those stars will see nothing except for our Galaxy, which is exactly the picture they had in 1915. All evidence of the Hubble expansion will disappear. Why? Because we won't see other galaxies moving apart from us. So they will have no evidence, in fact, of Big Bang. They won't see the Hubble expansion. They won't even know about dark energy, and I won't go into that. They won't know about the cosmic microwave background - it will disappear too. It will redshift away, and it turns out for fancy reasons: there is a plasma in our Galaxy and when the Universe is 50 times its present age the microwave background won't able to propagate in our Galaxy. All evidence of the Big Bang will have disappeared, and those scientists will discover quantum mechanics, discover relativity, discover evolution, discover all the basic principles of science that we understand today, use the best observations they can do with the best telescopes they will build and they will derive a picture of the Universe which is completely wrong. They will derive a picture of the Universe as being one Galaxy surrounded by empty space that's static and eternal. Falsifiable science will produce the wrong answer. In fact, I want to end with the good news. We live in a very special time, the only time we can observationally verify that we live in a very special time."