A bit of physics

People stand in front a large aquarium. Fishes and sharks swim in it.

Why is glass transparent?

If all things consist of molecules, why is it that some materials are transparent while others aren’t? Why is glass transparent?

The Copenhagen interpretation

We will have a look at the Copenhagen interpretation as proposed by Niels Bohr and Werner Heisenberg to explain the stranger things in quantum mechanics.

Spaces and dimensions

What do mathematicians and physicists mean with phrases like higher and/or extra dimensions? Let’s travel through a Universe of spaces and dimensions!

Heisenberg’s uncertainty principle

Heisenberg’s uncertainty principle is famous in quantum mechanics. However, it doesn’t have its roots in quantum mechanics. Let’s look at Fourier transform pairs.

The double-slit experiment

We describe the famous double-slit experiment, which proved to be fundamental to our current understanding of quantum physics.
A classical image of an atom is portrayed with an electron whizzing around the nucleus. They are all portrayed as balls, which is false.

This is not an atom

The standard cartoon of an atom is incorrect. An atom is not like a tiny planetary system. Quantum mechanics is all about the wave function. Let’s observe this carefully.

The meaning of E=mc²

The most famous equation may not be what you think it is. For example, it’s not about converting mass into energy. And, it’s only a part of the whole thing.

Rainbows: Alexander’s band

The band between the primary and the secondary rainbow is darker. The area underneath the primary rainbow is lighter. We explain Alexander’s band.

A radioactive smoking gun

Even physics tells us that smoking is bad. We briefly discuss what radioactivity is, what ionising radiation is, and how radioactive lungs become.
Astronaut Buzz Aldrin, lunar module pilot, walks on the surface of the Moon near the leg of the Lunar Module (LM) "Eagle" during the Apollo 11 exravehicular activity (EVA). Astronaut Neil A. Armstrong, commander, took this photograph with a 70mm lunar surface camera. While astronauts Armstrong and Aldrin descended in the Lunar Module (LM) "Eagle" to explore the Sea of Tranquility region of the Moon, astronaut Michael Collins, command module pilot, remained with the Command and Service Modules (CSM) "Columbia" in lunar orbit.

The Eagle has landed

We celebrate our 50th lunar anniversary. On this day, the Eagle landed.
A modern kitchen with a microwave oven. Is the radiation of a microwave oven unhealthy?

Is microwave oven radiation unhealthy?

We discuss what electromagnetic radiation is and why ionising radiation is dangerous. We discuss how a microwave oven heats up food, and vitamins too.
Clothes hang out to dry against a backdrop of mountains

Why do wet clothes dry?

We discuss the second law of thermodynamics, the notion of entropy, the statistical nature of the situation, and why wet clothes dry.

Just a minute: why do large and heavy ships not sink?

Until they do due to a mistake, ships do not sink, not even the large and heavy ones. Now and then, textbooks say this is because of dissimilar density. Though not a a wrong statement, it is also not a fundamental one. While ships may sink to the bottom of…
A computer-generated 3D image of a cup of coffee. The coffee, however, looks like a moderately turbulent sea. There's a tiny sailboat trying to avoid a lighthouse. All in this cup.

Why your coffee does not have tides

The moon orbits the earth and its gravity is causing the tides. But why don’t swimming pools have tides? Or a cup of coffee? Human bodies consist of water, mostly. Aren’t they tidally influenced by the moon? If you’re asking all these beautiful questions, then what you thought is causing…
A Hubble Space Telescope image of Galaxy cluster Abell 2537. The amount of gravity, that is, warping of spacetime, caused by this galaxy is visible through the bending of the light of stars and galaxies behind Abell. The galaxy works as a lens. All is predicted by Einstein's General Relativity.

Energy is neither fundamental nor conserved

Sometimes you may have heard someone say that, ‘in the end, everything is energy. Einstein himself said that mass equals energy, we are energy ourselves, light is energy, and everything in this universe is energy.’ Often, it is represented as the fundamental substance everything is made out of. And energy…

What is a spacetime interval?

Einstein and collaborators taught us that space and time are not fixed quantities. They can stretch and contract. They vary. There is one thing, though, that does not vary. It is the invariance of the spacetime interval.