Fusion is the energy that powers our Sun and other stars. It has been a goal of scientists around the world to harness this process by which the stars “burn” hydrogen into helium (i.e. nuclear fusion) for energy production on Earth since it was discovered in the 1940′s.
Nuclear fusion is the process by which light nuclei fuse together to create a single, heavier nucleus and release energy. Given the correct conditions (such as those found in plasma), nuclei of light elements can smash into each other with enough energy to undergo fusion. The “easiest” (most energetically favorable) fusion reaction occurs between the hydrogen isotopes deuterium and tritium. When the nucleus of a deuterium atom crashes into the nucleus of a tritium atom with sufficient energy, a fusion reaction occurs and a huge amount of energy is released, 17.6 million electron volts to be exact.
Why fusion? To put this in terms of energy that we all experience; fusion generates more energy per reaction than any other energy source. A single gram of deuterium/tritium fusion fuel can generate 350 million kJ of energy, nearly 10 million times more energy than from the same amount of fossil fuel!
Fusion power has the potential to provide sufficient energy to satisfy mounting demand, and to do so sustainably, with a relatively small impact on the environment. Nuclear fusion has many potential attractions. Firstly, its hydrogen isotope fuels are relatively abundant – one of the necessary isotopes, deuterium, can be extracted from seawater, while the other fuel, tritium, would be bred from a lithium blanket using neutrons produced in the fusion reaction itself. Furthermore, a fusion reactor would produce virtually no CO2 or atmospheric pollutants, and its other radioactive waste products would be very short-lived compared to those produced by conventional nuclear reactors.
The Meissner effect is the creation of a magnetic field from a superconductor during its transition to a superconducting state.
The above gif shows a magnet levitating above a superconductor being cooled by liquid nitrogen.
When you hop on a swingset, you make yourself swing higher and higher by using your legs—propelling your body either forward or backward depending on the direction you’re swinging. This shift in the position of your legs happens at a specific point as the swing moves (can you think of it?!) in order to help you swing higher—hitting that point in the cycle is what creates resonance. The frequency required to hit that point every time is called the resonant frequency.
This is the same phenomenon that allows you to tap a basketball that is motionless on the ground, and continue to hit it so as to bounce it higher and higher without stopping. Notice how you can’t just randomly hit the ball and expect it to continue to bounce higher. When you dribble a basketball from the ground to your waist you are dribbling the ball at its resonant frequency. And if you were superhuman, you could continue to dribble the ball at its resonant frequency until the ball collapsed from the force.
Which is exactly that happened to the Tacoma Narrows Bridge!
The Tacoma Narrows Bridge collapsed just months after its opening, and sparked greater research in the aerodynamics and resonance of structures such as bridges and buildings that are greatly affected by wind and weather.
A domino can knock over another domino 1.5x larger than itself.
The above Gif shows a domino 5 millimeters tall starting a chain reaction 13 dominos long that eventually knocks over a domino about half a meter tall.
If the reaction was 29 dominos long, the final domino would be the size of the Empire State Building.
The direction of light is bent in water by Total Internal Reflection.
Lightning Appreciation Post:
- There are nearly 500 lightning strikes every second around the world.
- Only about 100 of these strike the earth, the others are between and within the clouds themselves.
- Lightning is very visible from space (last gif from Astronaut Reid Wiseman)
- Besides regular storms (thunder storms, hurricanes, etc.) lightning can be found in volcanoes (gif 3) and even intense forest fires.
In conclusion: nature is fucking awesome!
Scientists believe dark energy makes up about 68% of the universe and dark matter about 27%. That leaves just 5% for us and everything we can actually see.
But what’s the dark stuff made of?
From the TED-Ed Lesson Dark matter: The matter we can’t see - James Gillies
Animation by TED-Ed
How Far Can Legolas See?
Minute Physics explores the science of sight in their latest video.
A nuclear reactor starting up.
The blue glow is Charenkov radiation.
The blue glow in the water surrounding nuclear reactors is Cherenkov radiation. The Cherenkov radiation actually comes from beta particles emitted by fission products. These beta particles are emitted with such high kinetic energies that their velocities exceed the speed of light in water. Just as a sonic boom is what results when a physical object exceeds the speed of sound, Cherenkov radiation is what comes out when a subatomic particle exceeds the speed of light. According to classical physics, a moving charged particle emits electromagnetic waves, if the particle travels faster than light would in a medium, the photons constructively interfere, resulting in a brilliant glow. The shorter the wavelength, the more blue the light appears. This is why visible Cherenkov radiation is observed to be blue. Although, most Cherenkov radiation is in the ultraviolet spectrum—it is only with sufficiently accelerated charges that it even becomes visible. Pavel Cherenkov discovered Cherenkov radiation in 1934, while he was studying the effects of radioactive substances on liquids. It is worth mentioning that before Cherenkov, in 1900, Pierre and Marie Curie had observed a blue glow in their experiments with concentrated radium. The explanation for the light was provided by Ilya Frank and Igor Tamm.