CASIMIR EFFECT AND HAWKING RADIATION

CASIMIR EFFECT AND HAWKING RADIATION

What is the Casimir Effect?

In 1948, a Dutch Physicist Hendrick Casimir came up with a method to detect a tiny force caused by zero-point energy or also known as vacuum energy exerted by virtual particles. To understand this phenomenon, imagine a rigid reinforced crate with a vacuum inside of it, so that you would expect for there to completely nothing within the crate. Now add 2 parallel mirrors about 100 atoms apart from each other into the crate. The result of this experiment is that the two mirrors miraculously end up moving towards each other, clearing the gap that was previously put between them. This strange behaviour completely questions our understanding of vacuums and whether vacuums are quiet and empty.

What is causing this strange behavior?

In order to explain this phenomenon, we must look carefully at Werner Heisenberg’s uncertainty principle, which states that you may not know both the position and momentum or the energy and duration of a subatomic particle to great accuracy (Δx Δp ≤ ℏ/2, ΔE Δt ≤ ℏ/2). So as our values for these variables tend towards zero the uncertainty also tends toward zero and hence according to the uncertainty principle particles cannot have both zero energy and zero duration, leading to the fact that particles which do not exist have a great chance of coming into existence for a short period of time from quantum vacuum fluctuation.

 These “virtual” particles occur in annihilation pairs (antimatter and matter particle pair) and very quickly eliminate each other or if you think of them as waves, they destructively interfere, cancelling each other’s amplitudes out, which has been proved by Einstein’s equation E=mc^2 and Planck’s constant, which lead to showing that particles can be modelled as waves with wavelengths by De Broglie . Due to the fact that waves can have an infinite amount of wavelengths, we know that there can be an infinite amount of different waves in open space but in our crate, they must be a form of a standing wave and harmonics of that a standing wave (which is still infinite) in order to exist between our mirrors.

There is a greater probability of having more particles on the outside of the mirrors than in between the two mirrors and these particles can collide with the mirrors exerting a force on the mirrors. As there is a greater net force pushing the mirrors together than the force pushing them apart, they come together.

However, when attempting to calculate the mass and energy of these particles, a lot of infinities were calculated so mathematicians had to result in renormalization, which pretends that these infinities do not exist. This effect is extremely useful in explaining Hawking radiation.

What is Hawking radiation?

After it has been detected that black holes emit radiation and shine, Steven Hawking attempted to prove that black holes do not shine and instead proved the opposite, by combining laws of quantum mechanics and general relativity and found out that stuff can escape near the event horizon of a black hole and that black holes do shine.

If an antimatter and matter particle pair is formed close to the event horizon, there is a chance of one of the particles getting sucked in by the black hole and the other one escaping so that they can no longer annihilate each other. This escape particle has an energy that we can detect as Hawking radiation. You would think that this violates conservation of energy but as from our point of view, this escape particle has positive energy meaning that the black hole must have gained negative energy, which is the same as the black hole losing mass, which is equal to losing energy, so that ultimately energy is conserved and the energy of the escaping particle is interestingly due to the black hole losing mass.

Black Hole Explosion

This phenomenon can lead to black holes being drained and decreasing in size. Hawking proved that as black holes evaporate by gaining negative energy, they increase in temperature so that the smallest black holes are the hottest ones. As the black hole’s mass decreases to zero, a powerful explosion of gamma rays will occur, which subsequently causes the most powerful eruption to ever be detected. This knowledge of black holes is due to the proof of vacuum energy by Hendrick Casimir and the Casimir Effect.

Is Mars A Waste or the Future of Our Civilisation? Should we travel to Mars, Venus, or Titan?

Two years ago, Elon Musk revealed SpaceX’s plans to colonise Mars; first, SpaceX plans to send two cargo ships to Mars in 2022, and then if successful, SpaceX will land two more cargo ships and two crewed ships in 2024. Now, there are less than 3 years left before this plan occurs and I, like many other physicists, doubt Musk’s plans.

Since 2017, new research has shown that Mars is indeed not the planet we should be focusing on – for example, the issue of radiation. The planet does not offer any natural protection against the galactic cosmic rays – high energy protons which originate from the sun, outside the solar system and even other distant galaxies. Mars has a very thin atmosphere and no magnetosphere which is a huge issue for our species.
Amanda Hendrix, a physicist and a senior scientist with the Planetary Science Institute, stated that “humans with the intention of spending any long period of time on Mars will probably have to live underground, or in some sort of device that will shield them from the rays.”  Now, if Mars is, indeed, a waste of money, where else can we invest our research, time and funding into? From my own research, the following are possible alternatives.

Venus

Our sister planet is often disregarded for its potential to be habitable for our species due to being the hottest planet in our solar system. However, Venus is an easier and cheaper alternative to Mars as the trip from Earth to Venus can be 30% to 50% shorter than a round trip to Mars. Unlike Mars’ very thin atmosphere, Venus’ atmosphere is quite thick, meaning much more protection against meteors and the cosmic rays. And most important of all, Venus has gravity, saving us from losing bone mass, while Mars does not – and we have not reached the advancements in science where we could even suggest ways of creating gravity artificially.
Now even after reading this you may ask, what about the incredibly hot temperature on Venus’ surface – how can we live on a planet where the temperature is over 450 degrees Celsius?
The answer to this question is indeed – cloud cities. NASA has hypothesised the concept of the High Altitude Venus Operational Concept (HAVOC) which would give us a lower temperature which is habitable for our species, whilst still having all the benefits.

Titan

The last alternative is Saturn’s largest moon – Titan. Unlike Mars, Titan has its own natural shielding due to the thick atmosphere, and the properties that make the planet much better for humans due to being an icy moon where water is present and oxygen can be obtained quite easily. Amanda Hendrix believes Elon Musk should be looking into Titan instead of Mars, stating “somebody like Elon Musk who has got the resources with the ability to work on Titan should focus on Titan instead of Mars” and she is quite right – Titan is a much easier and safer alternative than Mars – we would not have to devise a way to protect ourselves from the cosmic rays and the meteors, or worry about trying to find water. Now one might ask; isn’t Titan farthest away in comparison to Mars and Venus?
Despite being farthest away, it is still one of the more promising alternatives than Mars. NASA has recently started working on a ‘dragonfly spacecraft’ which could prepare us for starting a colony there and becoming a multi-planetary species and this would be done much more easily than Mars or Venus – the temperature of Titan would allow the spacecraft to last much longer than the other spacecrafts which travelled to Venus and only lasted up to a couple hours.  

Regardless of which planet we go to, we will certainly see a colony in our lifetimes as all the plans have been made to occur within the next decade – the prospect of our species becoming multi-planetary is imminent.