Thoughts on Reality
Have you ever thought and wondered if what you see, hear, smell, taste and touch is real?These are just some of my musings on why that is unlikely and that everyone probably experiences a different reality.
If you were one of those people in the picture with blindfolds on and all of you had never come across an elephant before – do you think the descriptions of your reality would be the same as theirs?
Before you start, please remember that reality is only for those with no imagination.
I thought I would start on the large scale and steadily work down. The universe is a good place to start as it is quite big. It is not infinite of course as it is granular ( I’ll explain that later ) but it has no boundaries as spacetime is curved. If you find this confusing, try going for a walk around the Earth. If you follow a straight line, you will eventually get back where you started from. So the Earth is not infinite but it has no boundaries either.
Gravity waves have recently ( September 2015 ) been detected for the first time after being predicted by Albert Einstein in 1916 as part of his general theory of relativity when he said that space and time were not separate but the same thing – spacetime. The gravity waves that were detected were ripples in spacetime caused by the clash of two black holes. This as the two black holes orbit each other and as they are accelerating, they give off gravity waves. This loss reduces their ability to keep away from each other until they are in a doomed inspiral until they merge. This type of gravity waves is called Compact Binary Inspiral Gravitational Waves. There are three other types that I won’t bore you with but, if you are interested, you can get more into the details here on the LIGO web site:
It took us just over 100 years to detect these waves after young Albert predicted them. Why did it take so long?
Gravity waves are very small ripples in spacetime and need huge masses accelerating very quickly so you need huge masses such as black holes and huge accelerations caused by those masses to produce detectable waves. We could never produce them on Earth as we do not have enough mass accelerating ( spinning ) fast enough.
Going back to 1916, Albert Einstein was the only person on Earth whose reality included gravity waves – everybody else, including Newton thought gravity was a force caused by masses attracting each other- so he had a different reality. Einstein thought that gravity was a distortion of spacetime caused by masses. A simple proof experiment can be carried out. Look at a star in the night sky. Then look at the same star with a mass, such as a group of galaxies close to your line of sight to the start. The star will look to be in a different position. The start hasn’t changed its position what has happened is that the mass has bent the light from that star. This disproves Newton’s theory – but only under certain circumstances – and proves Einstein’s as the distortion of spacetime caused by the galaxies has bent the light from the star. This called gravity lensing. If the lensing effect is large then multiple images of the same object can bee seen.
This is a good web site to read about gravity lensing:
So we now have two theories that are in conflict. Which is right, or righter?
Newton is good for ballistics on Earth and works well for everyday calculations. It was only proven to be slightly off by the very careful observation of the orbit of Mercury. This showed that Newtons theory was very accurate for anything moving at a small fraction of the speed of light. Errors only appeared when time was introduced to give spacetime – as in Einstein’s theory and objects were used that were moving at a larger fraction of the speed of light.
So Einstein’s theory is ‘true’ under all circumstances? No, but we’ll leave that box of spanners until a little later in this piece.
So was Newton wrong? No he was of his time and probably the most important scientist that ever existed. He was at the forefront of modern science and was aware of electromagnetism but it was not until Maxwell came along with his wonderful equations that it started to be understood. This how science works. Newton famously said that he was standing on the shoulders of giants. Most physicists since Newton are in turn standing on his shoulders.
Let’s move a little closer to home and think of things at a somewhat smaller scale.
You jump on a plane and fly across the Atlantic. From your point of view, high above the ocean, it appears flat, solid, blue and smooth. Your reality is that the surface of the ocean is solid and you could land on it. You land at Miami ( airport ! ), get a taxi to Miami Beach and go for a swim in the sea. It is no longer solid, it is granular, there are waves, boat wakes, fish and slippery, squirmy things and you probably cannot walk on it. Your reality has changed. Which reality is correct? You could say both but then how do you explain the difference?
As a side issue – if you go on a long haul flight – say across the Atlantic – the pilot will change course by a couple of degrees every so often. This so he ensures that he travels the least distance and saves some time and fuel. This is called the Great Circle Route and is shorter than a straight line between the two airports…
Now take a sphere of plutonium – not too much as it may reach critical mass and go “boom”.
Plutonium is a radioactive element and so PU 239 – the most important isotope – decays with a half life of 24,100 years. We’ll ignore another isotope of plutonium PU 241 is only 14.4 years so is soon ( ! ) nearly gone. Now, PU239 is made of molecules and atoms – which are all exactly the same. So how do they ’know’ when it is their turn to decay?
The only answer I can find is that Radioactive decay is determined by quantum mechanics – which is inherently probabilistic.
So it’s impossible to work out when any particular atom will decay, but we can make predictions based on the statistical behaviour of large numbers of atoms.
The half-life of a radioactive isotope is the time after which, on average, half of the original material will have decayed. After two half-lives, half of that will have decayed again and a quarter of the original material will remain, and so on.
Quoted from :-
Let’s read that bit again:
Radioactive decay is determined by quantum mechanics – which is inherently probabilistic.
I think that is great, but can anyone tell me what it means?
My take on it is this – treat this with caution – my speciality is writing fiction, which is defined as Telling lies and writing them down.
So if you take one atom of plutonium – PU 239. You sit and watch it for just a little over 24,000 years, you will have got to the half life and so there is a 50:50 chance the atom will have decayed. Nothing and no-one can say why – it is probabilistic! (If you put a lump in a bomb, is it probaballistic?) There is no mechanical cause and effect. So the question arises; does your reality include plutonium atom or not – I won’t get into the decay products and why Uranium has such a long half life. I also promise to eschew any talk of cats – dead or alive – or both.
Now consider the simplest atom of all – Hydrogen. It has one proton in the nucleus balanced by one electron. The question is, where is the electron? The old view was that it was in some sort of orbit around the nucleus. ‘Think of it as a mini solar system,’ was what I was taught at school. The current thinking is that the electron probably doesn’t exist. Until it interacts with something – another electron, an ion or perhaps you looking at it. Until then it will only exist as a probabilistic cloud. Then it will suddenly snap into existence.
So, if your reality is an individual hydrogen atom, you will always see the electron, because you are interacting with it but you can only measure its momentum or position. – never the both accurately. The more accurately you measure one the less accurate your measurement of the other becomes. This is because, at these very small scales the act of measuring will change the property you are measuring. For example, you may see an electron by looking at it but you need photons of light to see and a photon may well move the electron or change its momentum. This is called the uncertainty principle. It was developed and defined by Werner Heisenberg. More information here:
This also why, if the centre of the atom is a proton, with a positive charge, and the electron has a negative charge the they should attract each other until the electron crashes in to the nucleus. This doesn’t happen, because, if the electron moves closer to the nucleus then its position becomes more and more accurately know so ergo its momentum will be almost completely unknown so the electron may shoot off, out of knowing completely to allow it to comply with the uncertainty principle.
If the simplest atom acts like this then all atoms act like this then all matter acts like this – including us.Quantum mechanics is the best theory every developed. Experimentally everything works as it should. All computers, i phones etc are designed using quantum calculations but it doesn’t fit with Newtonian or Einsteinian physics.
So we come back to the question.
What is your reality?
If you enjoy thinking about this stuff then I strongly recommend this book. The theory in it is beautiful and it is wonderfully written – a joy to read. There is hardly any math in it so it is fun even if you don’t really do science.
Please let me know how you get on.
Reality is not what it seems: The journey. Carlo Rovelli
© Richard Kefford Eorðdraca
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