Probably the most familiar subject in physics is mass. Basically, it’s the amount of stuff something is made of. However, if you look at it a little more closely, you’ll find that the situation isn’t necessarily so simple. In this video, Fermilab’s Dr. Don Lincoln spends some time explaining how, conceptually speaking at least, there are two kinds of mass: gravitational and inertial and how the relationship between the two has huge consequences on our understanding of the universe.

Radioactive decay is the transmutation of one subatomic particle into another. In most instances, what happens is that existing particles move to new configurations. However in radioactive decays using the weak force, a particular kind of particle disappears and is replaced by a completely different particle. In this video, Fermilab’s Dr. Don Lincoln talks about how it all works and even describes a type of decay that has never been observed and, if it were observed, it would require the textbooks be rewritten.

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Of all of the known subatomic forces, the weak force is in many ways unique. One particularly interesting facet is that the force differentiates between a particle that is rotating clockwise and counterclockwise. In this video, Fermilab’s Dr. Don Lincoln describes this unusual property and introduces some of the historical figures who played a role in working it all out.

The laws of quantum mechanics and relativity are quite perplexing however it is when the two theories are merged that things get really confusing. This combined theory predicts that empty space isn’t empty at all – it’s a seething and bubbling cauldron of matter and antimatter particles springing into existence before disappearing back into nothingness. Scientists call this complicated state of affairs “quantum foam.” In this video, Fermilab’s Dr. Don Lincoln discusses this mind-bending idea and sketches some of the experiments that have convinced scientists that this crazy prediction is actually true.

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The behavior of matter can constantly amaze people, especially when extreme conditions are involved. In this video, Fermilab’s Dr. Don Lincoln describes what happens when a charged particle travels through a transparent material faster than light travels through that same material. When that happens, blue and violet light is emitted. This light is called Cerenkov light. This video tells you everything you need to know.

At any time in history, a few scientific measurements disagreed with the best theoretical predictions of the time. Currently, one such discrepancy involves the measurement of the strength of the magnetic field of a subatomic particle called a muon. In this video, Fermilab’s Dr. Don Lincoln explains this mystery and sketches ongoing efforts to determine if this disagreement signifies a discovery. If it does, this measurement will mean that we will have to rewrite the textbooks.

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Einstein's equation E = mc2 is often said to mean that energy can be converted into matter. More accurately, energy can be converted to matter and antimatter.

During the first moments of the Big Bang, the universe was smaller, hotter and energy was everywhere. As the universe expanded and cooled, the energy converted into matter and antimatter. According to our best understanding, these two substances should have been created in equal quantities. However when we look out into the cosmos we see only matter and no antimatter.

The absence of antimatter is one of the Big Mysteries of modern physics. In this video, Fermilab's Dr. Don Lincoln explains the problem, although doesn't answer it. The answer, as in all Big Mysteries, is still unknown and one of the leading research topics of contemporary science.

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After a century of study, scientists have come to the realization that the ordinary matter made of atoms is a minority in the universe.  In order to explain observations, it appears that there exists a new and undiscovered kind of matter, called dark matter, that is five times more prevalent than ordinary matter.  The evidence for this new matter’s existence is very strong, but scientists know only a little about its nature.  In today’s video, Fermilab’s Dr. Don Lincoln talks about an exciting and unconventional idea, specifically that dark matter might have a very complex set of structures and interactions.  While this idea is entirely speculative, it is an interesting hypothesis and one that scientists are investigating.

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Fermilab scientist Don Lincoln describes antimatter and its properties. He also explains why antimatter, though a reality, doesn't pose any current threat to our existence!

Carl Sagan's oft-quoted statement that there are "billions and billions" of stars in the cosmos gives an idea of just how much "stuff" is in the universe. However scientists now think that in addition to the type of matter with which we are familiar, there is another kind of matter out there. This new kind of matter is called "dark matter" and there seems to be five times as much as ordinary matter. Dark matter interacts only with gravity, thus light simply zips right by it. Scientists are searching through their data, trying to prove that the dark matter idea is real. Fermilab's Dr. Don Lincoln tells us why we think this seemingly-crazy idea might not be so crazy after all.

There are many mysteries of physics for which you can find explanations online and some of those explanations are wrong. In this video, Fermilab’s Dr. Don Lincoln takes on the mystery of why light travels slower in water and glass. He lists a few wrong explanations and then shows you the real reason this happens.

One of the most counterintuitive facts of our universe is that you can’t go faster than the speed of light. From this single observation arise all of the mind-bending behaviors of special relativity. But why is this so? In this in-depth video, Fermilab’s Dr. Don Lincoln explains the real reason that you can’t go faster than the speed of light. It will blow your mind.

The oscillation of neutrinos from one variety to another has long been suspected, but was confirmed only about 15 years ago. In order for these oscillations to occur, neutrinos must have a mass, no matter how slight. Since neutrinos have long been thought to be massless, in a very real way, this phenomena is a clear signal of physics beyond the known. In this video, Fermilab's Dr Don Lincoln explains how we know it occurs and hints at the rich experimental program at several international laboratories designed to understand this complex mystery.

Scientists were shocked in 1998 when the expansion of the universe wasn't slowing down as expected by our best understanding of gravity at the time; the expansion was speeding up!  That observation is just mind blowing, and yet it is true.  In order to explain the data, physicists had to resurrect an abandoned idea of Einstein's now called dark energy. In this video, Fermilab's Dr. Don Lincoln tells us a little about the observations that led to the hypothesis of dark energy and what is the status of current research on the subject.

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The quest to find the ultimate building blocks of nature is one of the oldest in all of physics.  While we are far from knowing the answer to that question, one intriguing proposed answer is that all matter is composed of tiny “strings.”  The known particles are simply different vibrational patterns of these strings.  In this video, Fermilab’s Dr. Don Lincoln explains this idea, using interesting and accessible examples of real-world vibrations.

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The Standard Model of particle physics is composed of several theories that are added together.  The most precise component theory is the theory of quantum electrodynamics or QED.  In this video, Fermilab’s Dr. Don Lincoln explains how theoretical QED calculations can be done.  This video links to other videos, giving the viewer a deep understanding of the process.

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In particle physics, there are many different types of particles, mostly ending with the phrase “-on.” In this video, Fermilab’s Dr. Don Lincoln talks about fermions and bosons and what is the key difference between these two particles.

Fermilab's Dr. Don Lincoln explains some of the reasons that physicists are so interested in supersymmetry. Supersymmetry can explain the low mass of the Higgs boson, provide a source of dark matter, and make it more likely that the known subatomic forces are really different facets of a single, common, force.

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The Higgs boson burst into the public arena on July 4, 2012, when scientists working at the CERN laboratory announced the particle’s discovery. However the initial discovery was a bit tentative, with the need to verify that the discovered particle was, indeed, the Higgs boson. In this video, Fermilab’s Dr. Don Lincoln looks at the data from the perspective of 2016 and shows that more recent analyses further supports the idea that the Higgs boson is what was discovered.

The data presented in this video can be seen in a technical form in this paper: http://cds.cern.ch/record/2158....863/files/jhep-08-04 Figure 19 is a more accurate version.

The Higgs boson was discovered in July of 2012 and is generally understood to be the origin of mass. While those statements are true, they are incomplete. It turns out that the Higgs boson is responsible for only about 2% of the mass of ordinary matter. In this dramatic new video, Fermilab’s Dr. Don Lincoln tells us the rest of the story.