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The Theory of Everything: The Quest to Explain All Reality

Keep your eyes peeled for black holes on this mind-bending search for a theory that could explain everything. No, really: Everything.
The Theory of Everything: The Quest to Explain All Reality is rated 4.5 out of 5 by 256.
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Rated 5 out of 5 by from Easiest Difficult Physics Course? Physics courses by Great Courses profs Pollock, Schumacher, and Wolfson beautifully describe principles, but their ability to translate into “plain English” varies. Example: there are two well-documented areas that often become muddled: E=mc2 and Relativity. Lincoln’s Lecture 4 (L4) stands out as providing the easiest explanations of both. His key to E=mc2 is to juxtapose it with its full equation [(E2 = (pc)2 + (mc2)2] by clearly discussing its limits: 1.) The case where there is no motion, 2.) The photon as an example where m = 0, and 3.) Cases where there is some mass AND momentum. Suddenly, the full equation becomes clear. In the same lecture he tackles Einstein’s relativity, not via the usual example of a person on earth vs. a traveler to another sun but via Minkowski’s enlightening phrase: “Essentially space and time are now known to be the same thing.” Instead of repeating the tired example of someone traveling to a star coming back younger than a sibling, Lincoln again clarifies via extremes: 1.) A person stationary in space experiences time but no translations in space; 2.) “At the speed of light there is only movement through space and no movement through time" (envision riding on a light beam). If in-between, one experiences both changes in time and space. His summary: the combined length of each individual's space-time vector remains constant. L5 not only describes inter-electron photon exchange as 2 electrons approach, it finally made clear to me the usefulness of Feynman diagrams and what levels of approximation are needed. L6 is the point at which one might be glad they decided to take Schumacher’s or Wolfson's course rather than this course. While Lincoln’s material is done stepwise, it is much more technically oriented and its steps are counterintuitive...yet his conclusions may well be worth the effort. L6's discussion of alpha emission helium emission by the strong force and beta emission via the weak nuclear force is pivotal (be sure to reference to the Guidebook’s page 8 illustration of the standard model) for the next 4 chapters. Those chapters will turn everything on its head as he reviews the sequential revelations of a massive array of particles and their interactions. If you can even incompletely follow these chapters, you will understand L9’s last paragraph: "Most of your mass isn't stuff. Our mass is really just the energy (of) subatomic tempests…we call protons and neutrons. Our mass is…just energy governed by the laws of QCD." (QCD= QuantumChromoDynamics. QCD includes “chromo” because “the charge of the strong force is color” - an irrational word choice made by quirky rational scientists.) While his course retains its unique approach, later lectures unexpectedly do not make a theory of everything sound any closer than older courses. Examples: L19 states “There is no possibility of (explaining everything) until we get a handle on dark matter”; L20: “How will we merge gravity and quantum mechanics, we simply don’t know” and “Superstring theory…perhaps…may identify the most fundamental building blocks of the universe…but is not wholly satisfactory.” Favorites include L16-17 on gravity; L18’s observation that 100 years ago we looked up and perceived only ONE galaxy (see also Wolfson’s Great Course “Physics” L59); L22: “Galaxies within 10 million light years are moving TOWARD (emphasis mine) us or with us…” The Guidebook (L22) has a (not to time scale) gorgeous diagram of the disk universe from the Big Bang to the present. L23 admits “multiverses” are not established science but “might lead to predictions that can be tested.” This is much better approach to the “multiverse” than Whittle’s palavering and wishful thinking stated as fact in the Great Course “Cosmology”. CONCLUSION: I have inadequate space describe Lincoln's unique tumbling mass of insight that leads to brilliant “Aha” moments. Buckle up.
Date published: 2024-05-06
Rated 4 out of 5 by from Requires some knowledge of advanced physics Well, I'm humbled! I think this is the first course in over 16 years of viewing the Great Courses that I have been simply unable to finish! This is NOT a criticism of the professor -- who is amiable, clear, and a great presenter -- nor of any production features; rather, it is to admit that in my 81st year on this planet I felt as if I were trying to learn a foreign language at my age! Which, in one sense, I was! Although I took chemistry and physics decades ago in high school and college -- a time when much of what this course presents was yet unknown! -- I always struggled with courses outside the humanities, the social sciences, and history. In fact, I later taught college history and then became involved in local and state government, both as an elected and appointed official. It was this world within which I learned to swim easily. While I did attempt to keep up with popularized sharing of information about scientific discoveries, as presented in the newspapers of yore, this was a far cry from learning the terms, let alone the theories, about which they spoke. Thus I faced a dilemma in "rating" this course! It would be unworthy of me to give it an unfavorable rating just because of MY ignorance, and yet I wanted to signal to others that unless they already possessed a solid basis in at least the language and figures of modern physics (and perhaps quantum mechanics) they, too, might find it something of a "hard go," as well. The older I get, the more I realize how very little that I, in truth, actually "know."
Date published: 2024-02-28
Rated 5 out of 5 by from Fascinating topic and lecture This is one of the most complex and fascinating courses I have taken.. I do have advanced degrees in science but still it requires some detailed attention to grasp the topic. Dr. Lincoln does an excellent job of presenting it to non science audience but definitely some background in science (Chemistry, physics, mathematics) helps to understand and appreciate the topic. He is definitely very knowledgeable and has first hands on experience in this topic. So, he is very credible and respectful. I admire him for his publications as well being able to present such complex topics to laymen. The graphs, pictures were very helpful to visualize the concepts. I highly recommend this course to anyone who is curious about the world, it’s development and its future. As he said, there are so much that we do not know about the universe and it’s origin. But thanks to science and scientists we also know a lot about the universe. The fact that we do not know everything should not prevent us from exploring more and giving up and relying on religion to tell us what happened without any evidence, experimental data and untested hypothesis.
Date published: 2023-09-16
Rated 5 out of 5 by from Excellent I purchased this recently and I am very impressed! The presenter is clear, concise and enthusiastic. The mark of a truly gifted person is the ability to explain complex topics making them understandable to the non-expert. Having finished the course, i will revisit it later to pick up on more...his quips add a light note to a fascinating subject!
Date published: 2023-09-11
Rated 5 out of 5 by from re: Lecture 18 "The Big Rip" The Big Rip seems to me a big rip. What do you think, Don? And would you consider this an original example of geek humor? :)
Date published: 2023-08-30
Rated 4 out of 5 by from Discovering The Theory of Everything Dr. Don Lincoln is an excellent speaker. Perhaps, the best I've ever heard! His topic is extremely difficult to present but bit by bit, he did it! I would like to tell him to consider acceleration as the unifying theory, of course factoring in the Lorentz Factor. My research supports this immensely!
Date published: 2023-08-09
Rated 5 out of 5 by from The Theory of Everything Don Lincoln is one of the best instructors on the Great Courses.
Date published: 2023-06-22
Rated 5 out of 5 by from Excellent content Excellent content with an excellent presentation from a great science democratizer
Date published: 2023-06-12
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Do you like a good detective story? Join a renowned scientist trying to solve nature's ultimate mystery.


Don Lincoln

There are so many clues from physics that are staring at us in the face. They are telling us something profound.


Fermi National Accelerator Laboratory (Fermilab)

Don Lincoln is a Senior Scientist at Fermi National Accelerator Laboratory (Fermilab). He is also a Guest Professor of High Energy Physics at the University of Notre Dame. He received his Ph.D. in Experimental Particle Physics from Rice University.

Dr. Lincoln's research has been divided between Fermilab's Tevatron Collider, until its close in 2011, and the CERN Large Hadron Collider, located outside Geneva, Switzerland. The author of more than 1,000 scientific publications, his most noteworthy accomplishments include serving on the teams that discovered the top quark in 1995 and confirmed the Higgs boson in 2012. He is a fellow of the American Physical Society and the American Association for the Advancement of Science.

His writing at a popular level includes many articles as well as four books: Understanding the Universe, The Quantum Frontier, The Large Hadron Collider, and Alien Universe. His enthusiasm for science education earned him the 2013 Outreach Prize from the High Energy Physics Division of the European Physical Society.

Dr. Lincoln has given hundreds of lectures on four continents to a broad range of audiences. He is a blogger for the website of the PBS television series NOVA, and he also writes a weekly column for the online periodical Fermilab Today.

By This Professor

Understanding the Misconceptions of Science
The Evidence for Modern Physics: How We Know What We Know
The Theory of Everything: The Quest to Explain All Reality
The Theory of Everything: The Quest to Explain All Reality


Two Prototype Theories of Everything

01: Two Prototype Theories of Everything

Embark with Dr. Lincoln on a search for a theory of everything-a simple and comprehensive explanation for all physical phenomena in the universe. Confront the incompatibility of our two best prototypes: the standard model of particle physics and the general theory of relativity....

33 min
The Union of Electricity and Magnetism

02: The Union of Electricity and Magnetism

Learn how two seemingly separate phenomena, electricity and magnetism, were shown by James Clerk Maxwell in the 1860s to be aspects of a single underlying force, demonstrating how unification works in physics. Then see how Maxwell's equations of electromagnetism make a remarkable prediction....

28 min
Particles and Waves: The Quantum World

03: Particles and Waves: The Quantum World

Follow one of the strangest turns in modern science: the discovery of the paradoxical world of light, which spawned the theory of quantum mechanics. Discover how light and matter behave as both particles and waves, and look at evidence for this curious feature of the quantum world....

32 min
Einstein Unifies Space, Time, and Light

04: Einstein Unifies Space, Time, and Light

Trace the reasoning that led Einstein to his special theory of relativity, proposed in 1905. Address common misconceptions about this startling new view of time and space, which led to ideas such as mass-energy equivalence, the impossibility of faster-than-light travel, and the space-time continuum....

30 min
Relativistic Quantum Fields and Feynman

05: Relativistic Quantum Fields and Feynman

Take a deeper step into the quantum world, observing how the theory of quantum electrodynamics, or QED, unites quantum mechanics with special relativity. Discover that the handy sketches of subatomic behavior called Feynman diagrams (named after physicist Richard Feynman) are really equations in disguise....

31 min
Neutrinos Violating Parity and the Weak Force

06: Neutrinos Violating Parity and the Weak Force

Study the weak nuclear force, which is responsible for beta decay: the emission of an electron from a nucleus during radioactive decay. Discover that much more is going on, including weird transformations that pose a challenge to a theory of everything....

31 min
Flavor Changes via the Weak Force

07: Flavor Changes via the Weak Force

Analyze more idiosyncrasies of the weak force, focusing on the three massive particles that mediate its interactions. Discover that the weak force is unique in its ability to change a characteristic called flavor, and learn that at high energies the weak force is exceptionally strong....

29 min
Electroweak Unification via the Higgs Field

08: Electroweak Unification via the Higgs Field

A key step in the quest for a theory of everything has been the realization that the electromagnetic and weak forces are aspects of the same force. Follow the saga of electroweak unification, which culminated in the discovery of the Higgs boson in 2012....

28 min
Quarks, Color, and the Strong Force

09: Quarks, Color, and the Strong Force

Explore the force that helps hold the atomic nucleus together, called the strong force. Chart the discovery of this mysterious mechanism-which only works at extremely short range-and see how it led to concepts such as quarks, gluons, and the color force, which is responsible for the strong interaction....

32 min
Standard Model Triumphs and Challenges

10: Standard Model Triumphs and Challenges

Bring together all the concepts studied so far to gauge how close physicists are to a theory of everything. Focus on the shortcomings of the standard model. Then zero in on two burning questions: Why is the mass of the Higgs boson so low, and why does matter predominate over antimatter?...

29 min
How Neutrino Identity Oscillates

11: How Neutrino Identity Oscillates

Transition to a new perspective as Professor Lincoln spotlights speculative ideas that may contribute to a theory of everything. In this lecture, explore the mysteries of neutrinos, which are extraordinarily hard to detect yet hold intriguing clues about the possible unity of fundamental forces....

31 min
Conservation Laws and Symmetry: Emmy Noether

12: Conservation Laws and Symmetry: Emmy Noether

Consider why mathematics is such an effective tool for describing nature. Then focus on mathematician Emmy Noether's remarkable insight that links symmetries in the equations of a physical system to conservation laws, such as the conservation of energy and conservation of momentum....

31 min
Theoretical Symmetries and Mathematics

13: Theoretical Symmetries and Mathematics

The first inklings of a successful theory of everything will probably arise from symmetries and group theory. Prepare for this epochal moment by digging into these important mathematical ideas. Also, learn to approach proposed theories of everything with fascination, tinged with healthy skepticism....

31 min
Balancing Force and Matter: Supersymmetry

14: Balancing Force and Matter: Supersymmetry

One of the most attractive ideas for physicists searching for a theory of everything is supersymmetry, which treats force- and matter-carrying particles as interchangeable. Explore major problems that supersymmetry solves and the shortcomings that convince some scientists that perhaps some other ideas must also be considered....

34 min
Why Quarks and Leptons?

15: Why Quarks and Leptons?

The fundamental building blocks of matter are thought to be quarks (which interact by the strong force) and leptons (which interact by the electromagnetic and weak forces). But could there be a deeper level? Explore the theory of preons, which may be even more fundamental than quarks and leptons....

31 min
Newton's Gravity Unifies Earth and Sky

16: Newton's Gravity Unifies Earth and Sky

Gravity is by far the weakest of the fundamental forces. Learn how Newton achieved the first major unification in physics by showing that terrestrial and celestial gravity are the same. He also tacitly equated inertial mass and gravitational mass, leading to the startling theory 250 years later....

29 min
Einstein's Gravity Bends Space-Time

17: Einstein's Gravity Bends Space-Time

Built on the equivalence of inertial and gravitational mass, Einstein's general theory of relativity explains gravity in a surprising new way. See how matter and energy determine the shape of space and time. Investigate confirming evidence for general relativity, including the discovery of gravitational waves in 2015.

32 min
What Holds Each Galaxy Together: Dark Matter

18: What Holds Each Galaxy Together: Dark Matter

Trace the discovery of missing mass surrounding most galaxies, which leads scientists to infer that 85% of all matter is "dark" and can't be observed directly. Evaluate the major theories about this discrepancy, and consider its implications for a theory of everything....

33 min
What Pushes the Universe Apart: Dark Energy

19: What Pushes the Universe Apart: Dark Energy

Turn to dark energy, the ghostly energy field that appears to be pushing the universe apart at an ever-greater rate. Learn how this extraordinary discovery was made in 1998, and explore theories that attempt to explain dark energy and its strange consequences....

32 min
Quantum Gravity: Einstein, Strings, and Loops

20: Quantum Gravity: Einstein, Strings, and Loops

A theory of everything must fit gravity into the quantum realm, reconciling the general theory of relativity with the standard model of particle physics. Explore the features of gravity that make this unification so difficult, and evaluate two intriguing approaches: superstring theory and loop quantum gravity....

31 min
From Weak Gravity to Extra Dimensions

21: From Weak Gravity to Extra Dimensions

Venture into extra dimensions to investigate gravity's extraordinary weakness compared to the other fundamental forces. This journey also sheds light on the possible creation of subatomic black holes in particle accelerators and why tiny black holes pose no risk to humanity....

33 min
Big Bang and Inflation Explain Our Universe

22: Big Bang and Inflation Explain Our Universe

Starting with the big bang, plot the history of our universe, focusing on events in the tiniest fraction of the first second, when phenomena such as supersymmetry, superstrings, and quantum loops may have come into play. Consider the explanatory power of the theory of cosmic inflation....

32 min
Free Parameters and Other Universes

23: Free Parameters and Other Universes

Now step into the realm of other universes. Do they exist? If so, how could we possibly know? Start by examining the free parameters that govern the structure and behavior of our universe. Then seek answers to four crucial questions that address why the parameters take the values that they do....

31 min
Toward a Final Theory of Everything

24: Toward a Final Theory of Everything

Finish the course by reviewing unified theories since Newton, analyzing a remarkable equation that brings major insights together and represents the current status of a theory of everything. Then look ahead to the next steps, and hear Dr. Lincoln's own research agenda for this momentous quest....

35 min