Scientists in a race to discover why our Universe exists

Yeah this isn't really a race to prove anything, it's a poor headline from the beeb.

The question is whether CP violation occurs for neutrinos, CP is Charge Parity conjugation symmetry.

Even if neutrinos do violate CP, that along with the known CP violation of Quarks will still not add up to enough to explain the
one in a billion preponderance of matter over antimatter in the universe so it still won't explain why matter won out over antimatter and why anything other than photons exist at all.

Anything they find out will only explain one thing in physics, it won't explain 'why' there is a universe and it will not explain in full why the part of the universe we can see is composed of Hadrons and Fermions rather than simply Bosons or rather more specifically just Photons.

Paul Dirac one of the greatest theoretical physicists of all time predicted the existence of neutrinos, something had to carry away extra energy when a free neutron decays into a proton and an electron however the actual particle wasn't found until 1956 the actual decay is beta decay and results in an electron a proton and an anti-neutrino, the neutrino carries away a little bit of kinetic energy that represents the difference in the mass of the neutron and the proton and electron it decays into, for a long time the neutrino was thought to be massless but it turns out to have a really tiny mass.

A friend of mine back in the late 1970s was studying physics at Paisley Tech, his final year thesis was on the Solar Neutrino Flux problem, we only saw about a third of the neutrinos that the sun should be emitting at us, he didn't solve it but worked on the possibilities.

A few years later the actual solution was discovered to be that neutrinos change flavour as they travel towards us from the sun and we were only detecting one of the three flavours.

This DUNE experiment is looking into the true nature of these elusive particles and that will help with our understanding of the standard model of particle physics or maybe it will send us off in a whole new direction which would be exciting but it's not going to explain why the universe exists, we are a long , long, long way off that explanation.

Fun facts, 100 trillion neutrinos are passing through your body right now, every second another 100 trillion neutrinos, they pass right through and interact with nothing, these huge underground detectors are there to detect the one or two that actually do interact occasionally with ordinary matter, these things are ghosts they could travel through a light years worth of solid rock like it wasn't even there.

And Paul Dirac a British physicist predicted their existence, his equation also predicted anti-matter almost a hundred years ago in 1931.

The field of study that deals with the origin of the Universe is really Cosmology, the question of where the Universe came from has led back to physics because the CMBR (Cosmic Microwave Background Radiation) points incredibly strongly to a point like origin for everything.

At this time the CMBR can only really be explained by the idea of cosmic inflation an idea proposed by Alan Guth and his colleagues back in the late 1970s and early 1980s however cosmic inflation is not without it's problems either.

The James Webb Space Telescope is starting to place limits on various ideas and it'll be fascinating to see where it all leads.

Einstein spent a large part of his later life trying to come up with a grand unifying theory that would unite all the forces of nature, Gravity, electromagnetism and the strong and weak forces, he failed.

There was an attempt at interpreting gravity and electromagnetism in a five dimensional space time by Kaluza and Klein, this was going on as early as 1919 the year my mother was born, 60 odd years later the work of Kaluza and Klein while not correct in itself led on to and was influencial in the birth of String Theory however there are lots of issues with string theory as well as it's largely untestable.

The BBC is still to my mind a superb source of news but it does tend to suffer from the tendency to go for sensational click bait headlines that so much of the news media suffers from today.

This DUNE experiment will still be very useful though, every experiment helps clarify the direction that theorists should next explore.

This would be a long post and I'm about to go to bed, however I'll say a little bit about the essential problem with Gravity and the big bang.

People have been thinking about motion and the paradoxes associated with it for thousands of years, we think of the space around us as being continuous essentially infinitely divisable, that's 'we' as in us normal plebs, it's the common sense notion of how the world works.

However how do we actually move from any one point to any other point, if I stand up and walk across a room how do the atoms that I am composed of actually move, say my atoms move 1 metre from where they were well they had to move a half of a metre at some point and at some point they moved 0.25 of a meter and at some point they had to move 10 cm and 1cm and 1 mm and 0.1 of a millimeter and so on.

The problem is that in a continum that is infinitely divisible you can always propose a smaller interval that has to be traversed and what is it that is doing the traversing, think about the infinity of real numbers between 0 and 1, there is 0.1, 0.2, 0.3 etc but there is also
0.0000000000000000001
0.0000000000000000002
0.0000000000000000003

but there is also

0.0000000000000000001000000000000000001
0.0000000000000000001000000000000000002
0.0000000000000000001000000000000000003

and basically you can always fit another smaller interval between point A and point B so how do we traverse that infinity of points when we move.

Ever thought about that problem? I first did as child but I didn't really have a grasp of the issue.

The Greek philosphers thought about that problem more than 2000 years ago and in part thats why they came up with the atomic theory that everything was made of tiny little particles, Paramenides believed that motion is only perceived but cannot acutally exist (that's from wikipedia) Democritus came up with atomic theory but of course that wasn't the same as our modern notion of atoms.

So what's all this got to do with the Universe and Gravity well the problem is that Einstein's theory of gravity which is stunningly accurate is a classical theory based on a continum and when we apply it to the Universe and the observations of Hubble (the person not the telescope) in the 1920s and 30s that all the stars in all galaxies were moving away from us didn't matter what direction you looked at in the sky in every direction everything else is moving away from us then we got the notion that the Universe and space is expanding.

So the implication is that if everything is moving away from us then once upon a time everything was much closer together and if you take it to extremes everything all the matter and energy in the whole universe was all crammed into one spot of zero length zero height and zero depth.

It's not as simple as that because that point also didn't change so there was no time and also because we are in space when the dimensions were zero there was no space, that means that space came into existence along with matter and time at the big bang (which was nothing like a bang or explosion).

On the other side of the coin we know that the maths of Einstein's General Relativity make it very clear that gravity increases with density and that if you cram enough matter into a small enough space the escape velocity to get away from the lump of matter will eventually exceed the speed of light at which point you have a black hole.

Back in the 1960s Roger Penrose showed that the inevitable consequence of cramming enough matter into a small enough space was a singularity, that's a point with zero dimensions, because nothing could hold up the matter against the pull of the gravity that was trying to crush it.

So the maths tells us that the Universe looked like a singularity when it was born and that it is now full of more singularities inside Black Holes as large stars die, the Black Hole is the event horizon that's the outside of the hole but on the inside of the hole physics breaks down because we end up with what appears to be the impossibility of a singularity.

Quantum mechanics was born when it became obvious to people that Rutherford's model of the atom as tiny solar system with a dense proton core and orbiting electrons like little planets couldn't work as the electrons would very rapidly spin down into the core and collide with the protons.

Quantum mechanics creates discreteness which applies to light, protons, electrons and energy levels and rewrites the picture of the atom, most of the stuff your chemistry teachers were telling you in school was a lie for the first few years because they knew that Rutherford's model of the atom was nonsense, if you paid enough attention you might remember them telling you about electron clouds a little later in school and that model was the quantum model of the atom.

So we get to the problem of today and that is that Quantum Electro Dynamics and Quantum Field Theory are incredibly powerful and accurate descriptions of what goes on at very very small scales and Einstein's General Relativity is and incredibly powerful and accurate theory of what goes on at large scales, but gravity doesn't play nice with quantum mechanics because gravity deals with a classical continum and quantum mechanics deals with discreteness.

Then we get to String Theory and I'll get on to that tomorrow

Continuation:

And then we have String Theory, in conventional physics particles appear like points things like electrons we're not even sure if they have any physical size they may actually be points, in string theory all the funamental particles are imagined to be different vibration modes of tiny strings analagous to the vibration modes of a guitar string, in string theory an electron is one vibrational mode and a proton another vibrational mode.

These strings are incredibly tiny and particles are imagined as vibration modes of single one dimensional strings.

So what has string theory got to do with universes either singular or multiple, short answer it doesn't really, it's just a framework that tries to explain the physical matter and the energy that makes up the world around us and it attempts to place gravity into a quantum framework as well unifying the field of gravity with electromagnetism and the strong and the weak interactions or strong and weak fields.

String theory relies on the concept of 11 dimensions of space, in some other versions it's 10 or 26 dimensions but in the most common version it's 11.

The vibrations that we see as particles like photons and electrons are strings vibrating in this 11 dimensional space, now we live in 3 dimensions of space so where are the rest of them, the idea is that the other dimensions are curled up really really small and something like an electron is a vibration of a string in that tiny curled up space, the vibrational mode determines all of the properties of the electron like its charge, its spin, its mass etc.

The maths of string theory is way over my head and even if I had graduated in physics if I'm honest with myself it would have still been way over my head but I take the word of those in the field that it is extremely elegant and beautiful mathematics.

The problem with string theory is that its dependant on the shape of those dimensions and if you change the shape of those dimensions then you get different predictions about the reality it is supposed to describe and unfortunately there are a vast number of possible shapes for those dimensions and each shape could represent a world that does not work the same way our work demonstrably works.

So that's saying that it's not really scientific in the sense that you can't get it to make predictions that match our reality without fiddling with the numbers and then you are down to the why is a specific shape or set of constants the ones that apply to our universe our world.

Now strictly speaking it does make predictions but they are outside the reach of our technology to likely to ever be testable, so is it still science?

It is however extremely elegant and it does unify gravity and the other forces of nature under a single mathematical framework.

So I'm still not talking about universes plural yet and the fact that string theory can descibe billions of universes that wouldn't look or work like ours is a fault in the theory if you look at it from one perspective or a prediction that other kinds of universes could exist from another perspective.

And yet I'm still not talking about a multiverse because we havent quite got a prediction out of string theory that can create a single expanding universe like ours directly out of just string theory.

So going back to Alan Guth and cosmic inflation and QFT (quantum field theory) QFT right now is the best interpretation of the Standard model of particle physics that we have, it makes testable predictions and it seems to cover all the bases apart from gravity, in QFT particles are ripples in fields, string theory kind of absorbs QFT as a subset but QFT is the thing that works right now.

Guth proposed the idea of the inflaton which is a scalar field it is has no direction or spin, in the inflaton field quantum fluctuations (random ripples) would generate a bubble that would look like the singularity state of our universe when it came into existence (it's almost impossible to avoid using temporal words like 'when' and 'before' but that's because we live in a world that has 'change' and therefore time).

That singularity, well quantum mechanics wants to avoid the singularity and give it dimensions no matter how small and from that singularity, the cosmic egg of our universe as it were, there was a sudden huge expansion that brought space and time into existence and the forces of nature began to crystallise out of the maelstrom out of the incredible energy that was being released, we don't know exactly which forces separated out first or when but it was likely to be gravity first followed by the strong and the weak and electromagnetic, the idea is that at the begining these forces were all the same thing and if it is ever to work then string theory would have to show how that unification of the forces could work at enormous energies.

The inflation idea surrounds the first tiny moments of existence we can't explain the uniformity of the CMBR (see above replies) without invoking an expansion of the universe at speeds far in excess of the speed of light, so now he's talking about breaking light speed but he also says that's impossible and I do, the thing is space can expand faster than light but energy and matter in the universe can't move faster than the speed of light, it was space that inflated not matter and it is still to this day space that is expanding not the matter in the space.

Lots of people really don't like the idea of cosmic inflation but it very effectively describes what we see when we point radio telescopes at the sky.

Guth did a lot of work on inflation and part of my understanding was that if you had a scalar field like the inflaton was that once it started it could never really stop and that implies the possibility that our universe is just one of many embedded in a higher dimensional framework of some kind and the intersection with string theory is that maybe every time the inflaton field blows off another bubble universe maybe the rules and the constants and the shape of the space that gets created is slightly different a different shape for those tiny curled up dimensions, that's the link to string theory.

This leads to the anthropic principle which basically says the universe we see around us is the way it is because if the constants were adjusted any other way then we wouldn't be here to be observers that could see this universe, it's a tautology but it's one that makes a lot of sense, string theory could give rise to billions trillions even maybe more recipes for a universe and only those recipes that could support the complexity of living beings could ever be occupied by living thinking reflective introspective beings.

To make it all even worse there are other kinds of multiverses implied by quantum mechanics that are not of the string theory variety and they probably exist in addition to the string theory/inflation driven variety as well but that's for another day.

I'm a layman trying to explain in laymans terms what I have grasped of this field over my lifetime, I did study Physics Maths and Astronomy at Glasgow Uni but for various reason never completed my degree but I've never stopped thinking about it throughout my whole life.

There may well be faults in my description above I would be surprised if there weren't but in terms of the history of science it's as good a description as I can give.

What I will say is that the real world is far more fascinating and awe inspiring when explored through science than any faith ever cooked up or imagined by human beings, physics and science are one of the ways we explore our lives for meaning I just happen to personally feel that it provides a more tangible connection with being alive and why anything exists than all the religions and small minded spoiled child like gods that humanity has invented.