The Evidence for Modern Physics: How We Know What We Know

Course Overview

Reveal the what and why of modern physics. A cutting-edge researcher explains how we know about black holes, gravitational waves, elementary particles, and much more. How do we know the universe is 13.8 billion years old? How do we know the speed of light is 299,792,458 meters per second? How do we know there are subatomic particles that live less than a trillionth of a trillionth of a second?

Studying how physicists make discoveries is the best way to understand key developments in modern physics—from quantum mechanics to the theory of relativity to cosmology. In this 24-lesson course aimed at non-scientists, noted particle physicist Dr. Don Lincoln of Fermi National Accelerator Laboratory covers more than a century of progress in physics, describing exactly how scientists reach the conclusions they do.

He starts with the atom, which was long hypothesized but wasn’t definitively proven until a paper by Albert Einstein in 1905. That was just the beginning, as researchers probed ever deeper into the atom’s complex structure, leading to the weird findings of quantum mechanics. Meanwhile, Einstein’s more famous work in relativity overturned conceptions of time and space, especially in the realm of the super-fast and ultra-massive.

Relativity and quantum theory are notoriously counterintuitive, but Dr. Lincoln shows why their conclusions must be true. He does the same for cosmology, which has advanced from the view that the Milky Way galaxy is all that exists to the realization that there are likely a trillion galaxies in the observable universe. Along the way, he deals with the Big Bang, black holes, dark matter, dark energy, and cosmic inflation, among other ideas.

Course Lectures

01: Do You Believe In Atoms?

Dr. Lincoln opens the course with the observation that all matter is made of atoms. But how do we know? The atomic hypothesis goes back to antiquity, although that was just an inspired guess.

Duration: 28 min

02: Peering inside Protons and Neutrons

Peer inside atoms to find mostly empty space, along with electrons and a compact nucleus, composed of protons and neutrons.

Duration: 31 min

03: Seeing Light as Wave and Particle

Probe one of the most baffling mysteries of physics: the wave-particle duality of light.

Duration: 29 min

04: The Paradox of Quantum Entanglement

Dr. Lincoln boldly confronts the paradox of quantum entanglement, which governs the behavior of particles that share the same quantum state.

Duration: 30 min

05: How We Know Special Relativity Is Real

Learn how Dr. Lincoln routinely conducts experiments that show the bizarre effects of Einstein’s special theory of relativity.

Duration: 28 min

06: Why the Speed of Light Is the Speed Limit

How can the speed of light be the same for everyone, regardless of their state of motion?

Duration: 28 min

07: Discovering Subatomic Particles

Survey the fundamental particles and forces of the Standard Model, which is the prevailing theory of particle physics.

Duration: 28 min

08: How Do You Weigh a Quark?

Learn the secret for measuring the masses and lifetimes of subatomic particles that exist for roughly a trillionth of a trillionth of a second.

Duration: 27 min

09: Capturing the Ghostly Neutrino

Hear the story of the neutrino, the ghostly particle that passes through you at the rate of one quadrillion per second.

Duration: 30 min

10: The Search for the Higgs Boson

As a member of the research team, Dr. Lincoln recounts the discovery of the Higgs boson, one of the major science stories of the past half century.

Duration: 30 min

11: Are Man-Made Black Holes Dangerous?

Evaluate three alarmist scenarios for a physics experiment gone horribly wrong.

Duration: 29 min

12: How We Know What Stars Are Made Of

Scientists did not know the exact composition of the Moon until astronauts brought back rocks.

Duration: 31 min

13: Forming the Milky Way and Other Galaxies

Until 100 years ago, our Milky Way galaxy was thought to comprise the entire universe.

Duration: 31 min

14: Finding Planets around Distant Stars

Planets beyond our solar system weren’t discovered until the 1990s.

Duration: 28 min

15: The Awesome Evidence for General Relativity

Dr. Lincoln introduced Einstein’s special theory of relativity in Lesson 5. Now he covers general relativity.

Duration: 29 min

16: The Hunt for Gravitational Waves

General relativity predicts that titanic events such as colliding black holes cause the fabric of spacetime to ripple with gravitational waves.

Duration: 29 min

17: How We Know the Universe Began with a Bang

The Big Bang is one of the few scientific concepts that has entered popular culture.

Duration: 31 min

18: The Case for Cosmic Inflation

Unlike the well-founded theories you’ve studied so far in this course, turn to one that is as-yet-unproven—but mindboggling in its implications.

Duration: 30 min

19: How We Know Dark Matter Exists

Dark matter is the conjectured substance that outweighs ordinary matter by five to one.

Duration: 32 min

20: How We Search for Dark Matter

Dig deeper into the quest to understand dark matter.

Duration: 32 min

21: How We Know the Universe Is Accelerating

Investigate evidence that the expansion of the universe reversed its gradual slow-down and stepped on the accelerator 5 billion years ago.

Duration: 30 min

22: Measuring the Size and Age of the Universe

Draw on the astonishing facts about the universe you have learned since Lesson 15.

Duration: 32 min

23: What We Know about Quantum Foam

Few claims of physics are as absurd as that empty space is writhing with “virtual” particles.

Duration: 29 min

24: Are Space and Time Quantized?

Finish the course with a leap into one of the most speculative realms of physics—the quest to understand gravity at the quantum scale.

Duration: 33 min