What is relativity? Is Einstein wrong?

In 1905, a Swiss patent clerk shook the seemingly well-established foundations of physics with four groundbreaking papers – one proving the existence of atoms, another proving mass-energy equivalence, another proposing ‘energy quanta’ and a final one on relativity. This patent clerk was Albert Einstein, and he had just disproved the several century-old papers of Isaac Newton; proving time was not absolute, but relative, and that Newton’s law of universal gravitation was incorrect. Einstein had effectively paved the way for modern physics to progress, but could he have been wrong? 

Newton

In the 17th century, Isaac Newton devised the law of universal gravitation; put any masses anywhere in the Universe, a fixed distance apart, and you will know the gravitational force between them. At the time this explained everything from the terrestrial motion of cannonballs to the celestial motion of comets, and stars, as well as objects on planet Earth, and this law’s predictions matched every observation or measurement that had ever been made for almost two centuries until physicists noticed a flaw they could not explain – Mercury’s orbit, which was completely different to the other planets’ orbits in our solar system, as the orbits of planets shifted over time, and Mercury’s orbit shifted so much faster than Newton predicted. This was a flaw that no physicist at the time would dare challenge, as Newton’s ideas had been well established for centuries, and he was considered to be absolutely correct. Newton also devised that time was absolute, claiming time exists independently and progresses at a consistent pace throughout the universe. Despite both of these ideas being flawed and disproved several centuries later, we still use them for certain calculations, such as for rocket launches.

Einstein

In the early 20th century, however, the young Albert Einstein devised several new ideas which contradicted the ideas of Isaac Newton and also provided an explanation for Mercury’s pesky orbit around the sun. Instead of exerting an attractive force like Newton, he argued that each object in our universe curves the fabric of space and time around them, forming a sort of well that other objects (and even beams of light) fall into. A great way of understanding this is through picturing the sun as a bowling ball on a mattress. It creates a depression that draws the planets close. This effectively had solved the Mercury problem - the sun curves space so it distorts the orbits of nearby bodies, including Mercury. This claim was verified through the observational Eddington experiment in 1919, whereby physicists measured the gravitational deflection of starlight passing near the Sun and saw that the values obtained from this experiment matched Einstein’s values in 1905.

Einstein also successfully proved the existence of the atom through the usage of the kinetic theory of gases, as well as receiving help from Jean Perrin’s Brownian motion experiments which verified Einstein’s claims. Using Max Planck’s work, he also successfully devised the photoelectric effect, which proposed that there is an emission of electrons when electromagnetic radiation, such as light, hits a material. And perhaps his most famous proof of all – mass-energy equivalence, which brought about the famous equation E = mc^2 (where E = energy, m = mass, and c = speed of light) – since mass and energy are equivalent, we can use this equation to calculate the amount of energy, as Einstein states that “all objects having mass, called massive objects, also have corresponding intrinsic energy, even when they are stationary”.

Thanks to all of these, we have been able to predict how much energy will be released or consumed by nuclear reactions, have been able to create the atomic bomb, GPS and other modern electronics as well as the age of stars, the distance to the stars. Einstein’s contributions to science, as well as to our society, have been astronomical.

Now, what if Einstein was wrong? Centuries before Einstein, we believed that time was absolute; that there was an audible tick-tock throughout the universe, but just over a century ago we learnt that time was relative – surely we can apply the logic that in a couple centuries, Einstein too, would be incorrect about much of his work just like Newton was? 

We, physicists, have already started to notice errors in Einstein’s work, although general relativity is still a very well confirmed theory. General relativity, as stated earlier, predicts that light bends around massive objects, and predicts that the universe should be expanding; that black holes exist, that time runs more slowly in certain gravitational potentials, and so on, all of which we have observed and know are facts. 

However, it does not fit well with another well-confirmed theory – quantum mechanics. Particles obey Heisenberg’s Uncertainty Principle, and so can be in two places at the same time. If we have two slits and shoot a particle towards it, quantum mechanics tells us that the particle will go through both slits. But thanks to Einstein, we are unsure as to which direction this particle will subsequently go after travelling through both slits at the same time due to the gravitational pull.

Aside from the double-slit problem, there are several other issues. One is with singularities in general relativity – a singularity is a place where both the energy-density of matter and curvature become infinitely large, such as with black holes and the beginning of our universe. It has been quite well established that this is flawed and that there is a more fundamental theory to replace it – quantum gravity. Another reason is that if we combine quantum theory with general relativity without quantizing gravity, we find that black holes will slowly shrink by emitting radiation (known as Hawking radiation thanks to the discovery of Hawking), suggesting that black holes can entirely vanish by emitting such radiation. This radiation emits only temperature and no other information, so we cannot possibly know what formed the black hole, ergo general relativity cannot fit with quantum theory.

If we are indeed incorrect, then we would have to ‘recalibrate’ everything we have come to know thanks to Einstein, such as GPS and the age of stars, as well as the other discoveries stated earlier.

We are constantly progressing in science and as a society at an incredible rate, and much of what we believe today will most certainly be disproved in several centuries, if not decades; religion, cancer, blindness, death, violence; all may become things of the past thanks to our work in physics. 

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.

Significance of Maxwell’s Demon for the understanding of Entropy, Information and Time

Significance of Maxwell’s Demon for the understanding of Entropy, Information and Time

As far as our understanding of the Universe goes, all the physical laws that govern Nature are time-reversible except for the Second Law of Thermodynamics which states that the change in entropy in an isolated system can never decrease ( ΔS≥0) , which makes it appear time irreversible as going back in time would mean decreasing the entropy of the closed system and hence violating the second law of thermodynamics. Imagine cracking an egg, once cracked for it to reseal itself it would have to decrease in entropy and go back in time without any external forces if modeled as a closed system.

What causes entropy to increase?

If we model a rigid body such as a crate with a barrier in the middle, half of the crate is filled with a gas and the other half is a vacuum. On removing the barrier, we increase the volume that the gas fills as gasses are known to expand into the shape of their container; this results in an increase in entropy because now there are more ways to describe the microstates of the system, meaning that there more possible arrangements of gas molecules within a larger volume then a smaller one, which was proved by Ludwig Boltzmann with his equation for entropy, which is interestingly carved on his tombstone, S=klogW ( where k is Boltzmann’s constant and W is the number of real microstates). You would think that if we compressed the gas back to its original volume, we would decrease entropy and hence violate the second law of thermodynamics. However, compressing the gas requires external work to be done, which in turn increases the temperature of the system and increase the kinetic energy of the gas molecules, so that there are now more ways to describe the dynamics of the molecules compared to a cooler system, which results in an increase in entropy.

In 1867, James Clerk Maxwell, who is known for his theory of electromagnetism, devised a thought experiment, which was later known as Maxwell’s demon. To understand this brilliant experiment, once again imagine our crate but this time the barrier has a frictionless door on it that opens and closes to let molecules go through. At first, the door is open until the gas molecules spread out evenly on both sides of the door. Now imagine a demon that controls when the door opens and closes and only opens the door so that the molecules only travel into one half of the box and not back into the other. This would result in a decrease of entropy, as no external work is being done, and a violation of the second law of thermodynamics. This seemed completely plausible and was a mystery for more than 100 years.

In 1982 Rolf Landauer and Charles Benneth solved this problem by proving that in order for the demon to know when to open the door to reduce entropy he has to gather information about the motion of the molecules, which in turn increases the entropy inside his brain. Following this ground-breaking discovery, they proved that the increase in entropy in the demon’s brain counterbalances the decrease of the entropy of the gas molecules as the demon is part of the system . Moreover , scientists argued that you can just erase the demon’s memory but Benneth and Landauer proved that erasing information requires external work, leading to an increase in heat and entropy and hence obeying the second law of thermodynamics. This discovery redefined entropy as the information required to describe all the microstates of a system, meaning that if entropy was decreasing we would not have memories and consciousness.

What does time have to do with entropy?

An astronomer Arthur Eddington hypothesized that the increase in entropy was responsible for the increase for the forward flow of time as the second law of thermodynamics is time irreversible just like the flow of time? This is because the entropy of the universe tends to increase as the volume of the Universe is constantly expanding at an accelerating rate and hence there are more ways for molecules to arrange themselves in the future than in the present just like a chessboard with game pieces. However, for now, this is just a theory and it is not known for certain what causes forward time flow.

Can we violate the second law of thermodynamics?

Yes, however it is extremely improbable. Imagine our rigid box but this time with no barrier, the gas molecules can arrange themselves so that they all are on one half of the box. So, therefore, we have not inputted any extra work into the system to produce heat and we do not need information on the motion of molecules, which means that the entropy has spontaneously decreased, violating the second law of thermodynamics. However, the chance of this is 1 in 10^150,000,000,000,000,000,000,000, leading to the fact that the second law of thermodynamics must be a statistical law and not absolute! Continuing with Eddington’s postulate, does this mean that backward flow of time is also not impossible but just extremely improbable?

The Millennium Problems; The Navier-Stokes Equation

In May 2000, the Clay Mathematics Institute stated 7 of the perhaps most significant problems in Mathematics at the time. One of the most notable problems of them all is the Navier-Stokes Equations.

The Navier-Stokes Equations came about from applying Newton’s Second Law to fluid dynamics; they describe the relations between pressure, temperature, velocity and density of any moving fluid. Think of any fluid and these equations will explain their behaviour. They subsequently become quite useful, describing the physics of many phenomena, not necessarily in physics, but in other fields as well; they are often used to model weather, ocean currents, water flow in a river, or the flow of air around the wing of a plane; aiding in the design of aircraft and automobiles, the study of blood flow, and the analysis of pollution. Surprisingly, they have also been quite important in the world of gaming as well, and have also been used to study magneto hydrodynamics (assuming you model the equations with Maxwell’s equations, which can help understand how stars and galaxies form – this means we could also potentially model the growth of the sun as well as other significant stars in our galaxy.

While we do have the equations and while solutions may exist with the equation, they are only behaved in 2 dimensions, yet we live in 3 dimensions (assuming you ignore the 4^th dimension of space-time), which affects the equations quite a lot, and we mathematicians have been unable to figure out why these equations do not work in further dimensions. This may be because there is either no way of understanding these equations in such dimensions, or of the possibility that we have not made enough progress in order to potentially find out the solution for further dimensions – meaning we may not be able to solve this problem until we have reached the stage in advancements where we’d understand the problem further.

This Millennium Problem, like all the others, has a prize of 1 million dollars. Only one of the seven problems has been solved, which was the Poincare Conjecture by Grigori Perelman in 2003. Shockingly, he refused to accept the million dollar prize, which shows how many mathematicians out there are not doing such questions for the sake of money, but to further our understanding of such mathematical matters, which often change the course of history as well. Now, the CMI is not asking you to exactly ‘solve’ the problem, but to “further our understanding of the Navier-Stokes Equations” which suggests that we do not need to solve it – we could just prove that it cannot be solved. And so the question remains; who will further our understanding? 

 

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.

Quantum Theory and the Nuclear Atom

Quantum Theory and the Nuclear Atom.

There are two ways of finding what atoms or other small particles are like. One is to fire something even smaller at them and see how they break up or how the projectile bounces off of them. The other is to shake them about (giving energy) and seeing what comes out. 

PROBING THE ATOM WITH ALPHA PARTICLES

The initial method was used for a productive experiment in 1909. Alpha particles of a radioactive source were fired at a thin film of metal atoms. This was called the Geiger-Marsden experiment; some particles bounced back at angles, which meant that they had hit something smaller and with mass. From this Rutherford ( a physicist) worked out in 1911 that an atom has a positive nucleus surrounded by negative electrons. He suggested that electrons could be orbiting about the nucleus like planets around the sun. However, such an atom would not be stable; an orbiting electron, like an orbiting planet, has an acceleration directed towards the attracting object. An accelerating electron continuously radiates electromagnetic waves, so should lose energy and spiral into the nucleus.

Rutherford's model was saved in 1913 by Danish physicist Niels Bohr. He used the unique quantum ideas of energy, saying that the electron could have only certain 'allowed' energy states; with definite energy gaps between them corresponding to definite orbits. So electrons could not lose energy continuously and spiral into the nucleus. Electrons could only move between the orbits by gaining or losing definite, set quanta of energy. 

This did indeed seem a very far-fetched idea at the time, but Bohr backed it up with calculations of how much energy an atom could gain/lose and matched this with the energy of the light quanta it had emitted. 

Bohr did not explain why the electron couldn't fall into the nucleus. This had to wait until a later version of quantum theory.

"A physicist is just an atom's way of looking at itself."  

- Niels Bohr.

What is Mitosis?

What is Mitosis?

Mitosis is one type of cell division that takes place in body cells.

A body cell is any cell except those that produce gametes (sex cells).  

The cell that is dividing is called the parent cell, and two new cells are formed because of it; called daughter cells. The daughter cells are identical to the parent cell, so if the parent cell is diploid then the daughter cells will be diploid too. 

There are several stages of mitosis, which repeat and repeat.

1. The first stage of Mitosis is called Interphase; at the end of interphase, chromosomes start to become much more visible. The DNA has already been copied. 
2. The second stage of Mitosis is called Prophase; the nucleolus disappears.
3. The third stage of Mitosis is called Metaphase; which is when the nuclear membrane begins to break down. Chromosomes line up along the middle of the cell.
4. The fourth stage of Mitosis is called Anaphase; the chromatids here separate and one chromatid from each pair is pulled to each pole of the cell. The chromatids can now be called chromosomes. 
5. The fifth stage of Mitosis is called Telophase; The spindle fibres disappear and a new nuclear membrane forms around each group of chromosomes/
6. The cell splits into two, which is called Cytokinesis.

Please note that Mitosis is much more advanced than this; this is a basic description of what Mitosis does.

WELCOME TO THE SCIENCE BLOG!

Dear Reader, Welcome to My Blog!

This is a blog for the scientist, the science and mathematics student, or anyone who just likes science and enjoys reading about it.

My name is Avesta Afshari-Mehr. I am currently a Mathematics student based in the United Kingdom. I hope to study Natural Sciences at Cambridge University in 2 years. 

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