How can it be infinite? What nonsense . .

The subject of a flat infinite universe came up again, on the physics forum.  For the first time I expressed my frustration at the claims that the universe might be infinite, and explained that infinity is just a mathematical term that does not have to be realisable.  The discussion highlighted the standard theory that the Big Bang is the point from which everything exists.  The universe does not seem to have been infinite then, so why should it be now?

I made the point that a mass is attributed (around 10^57 kg I believe).  Yes, this is understood to be of the visible universe.  A lot of stuff we can't see due to expansion in the last 13.5Ga, but it all still stems from the Big Bang.  So why do physicists like Brian Cox say, as he did again on TV last night, that the bit we can't see might be infinite?

All it takes is for the boundary to be defined.  The surface of a sphere defines the boundary of the sphere, but the surface itself has no boundary, you could walk round it for ever.  Extend by one dimension, so the volume of the universe has no boundary, but it has to form the boundary of a 4-dimensional entity.  This is the big conundrum, because GR has been defined to work in three spatial dimensions, and a fourth would mean that gravitation would not work as it does.  The inverse square law would be an inverse cube law, and that is not what we see.  Or is it?

There are some problems with GR.  It does not reconcile with quantum, with gravitation being the odd one out in the unification of primary forces.  It should be explaining Dark Matter, instead there are teams of scientists and engineers trying to detect matter that is only detectable through its gravitational effects!  It offers as an option the prospect of the universe being infinite, a nonsense to cover the fact that they don't know the shape of the thing they are talking about.

There is clearly a sense in which GR needs modifying to account for these well-known observations.  Start with an assumption that reality is finite, and that Dark Matter is an artifact of gravitation at the cosmological scale.

Dark Matter soon to be found !

The BBC has just reported that the search for dark matter is reaching a crux http://www.bbc.co.uk/news/science-environment-24733131 as measurements are now sensitive enough to have a high chance of finding it, if it exists.  I don't think it will be found, and now that a result is expected, it should start to change the direction of big physics when it is not.

As the article says "Dark matter is thought to make up 27% of the Universe. But astronomers have only been able to infer its existence through the gravitational effects it has on visible matter in the Universe". Surely it is much more reasonable to look for a gravitational explanation for the phenomenon, than to seek stuff that does not absorb, emit, have temperature or any other detectable characteristics.

We know that gravitational mass and inertial mass are the same thing.  I am also hanging my hat on the assumption that gravity is not a real force, but a fictitious force like centrifugal force.  If so it means that another set of physicists trying to reconcile gravity with the three fundamental forces are sort of wasting their time.  So if we have a system comprising a horizontal perfectly smooth table with a hole in the centre, a string through it holding a mass underneath connecting to a mass on the table, when the upper mass orbits the hole at a speed giving equilibrium, we have tension on the string caused by two fictitious forces balancing each other.  Tension in the upper part is centripetal force causing the upper mass to change its direction twice every revolution.  The equal and opposite lower-string tension is what is traditionally called the reaction force of the Earth opposing gravity's force, but is in fact the string accelerating the lower mass (F = m a) (though it appears stationary) at a rate of 9.81m/s^2 upwards.  Everything sitting on the surface of the Earth is experiencing a push upwards which amounts to the same thing.

This means, as I understand it from L2 Physics, that we are in a rotating (non-inertial) frame of reference (not the Earth rotating, that is irrelevant, I mean the whole of spacetime).  I expect that general relativists know this very well.  The quandary is that our environment is shaped such that the distance between ourselves and any recumbent antipodeans is not changing even though our relative acceleration is -19.62m/s^2.

The reference point is the centre of the Earth, the thing that is bending spacetime locally to result in this behaviour.  So the question is either (a) are three spatial + one time (3S+T) dimensions enough, and time is real enough to enable gravity, or (b) is a fourth spatial dimension (4S+T) required, as I have been arguing for a while now.  My reading of the subject so far tells me (a) that there cannot be a fourth large spatial dimension, or the inverse square law would have to be inverse-cube law, which it isn't, and (b) that physics doesn't need time, except to deal with entropy.  Well I'm sorry but you can't have it both ways.

If GR already explains how masses accelerating away from each other can also not be changing their distance apart, then surely the role of time is fundamental, and surely the shape of the Universe should be something that can be described in some way.  I look forward to seeing it.

Meantime I wait for the news that dark matter is made of cheese . . .

Silver Hammer Man

Inflation is an important topic to address.  Any model needs to include it, as the evidence from the CMB makes the fact of it generally accepted, yet it requires several leaps of faith to do so.  For that very short period of time everything exceeded the speed of light, and then it ceased abruptly.  I’ve not studied it very deeply at all yet but am still intrigued by how such a force or impulse could exist and then cease so momentarily, and even when the force subsided the speed thus imparted to all masses should surely have made the whole lot explode.

The obvious retort is that as everything was so close, gravity was very strong and reined in a runaway expansion.  But this was before the laws had settled down: and anyway I can’t use gravity to explain itself.  Fortunately.

The quick answer is that during inflation the shape of the universe was unfolding.  I would rather call it a deployment, like the unfurling of solar panels, antenna arrays and instruments on a newly-launched spacecraft.  Pre-deployment, it fits into its launch shroud and has been given spin of about 1Hz for stability, and post-deployment is 3-axis stabilised, often around a gyro system using magnetic bearings for contact-free rotation, the flywheels spinning at around 20k rpm I seem to recall.  But for the 4-D toroidal universe the idea of an inflating flotation ring is also apt.

Sam has already dubbed the Big Bang the ‘Big Spin’.  Well first came the release of the enormous bubble of energy in an unstable form, and immediately after, its inflation to a form which gave the universe its shape and stability, which included conversion of most of the energy into rotational potential energy.  This model requires mass to carry moment of inertia, so would have to include that mass condensed by this stage.  So in a flash we have a 4-D flywheel of rotating spacetime with which masses engage to store energy losslessly.  Masses can’t exceed the speed of light, and electromagnetic radiation flies around at the speed of light (or would if the medium wan’t still opaque).  What is the nature of the engagement of spacetime with EM energy and mass?

Maxwell’s equations are cited as the four most significant ever.  He also determined that visible light is EM radiation because his speed calculation matched its measured speed, and thereby predicted other forms of EM energy, verified soon after by Helmholtz and Hertz.  ε₀ and μ₀ define the spacetime engagement relationship of the electric and magnetic components respectively, and in EM radiation these components can’t exist separately.  But how does mass engage with spacetime?  It has to be fundamental, and we can recall Maxwell found that 1/c² = ε₀μ₀.  Sure thing, mass can’t go faster than c.  The harder it is pushed, the more its inertia increases to oppose further acceleration.  Spacetime has a grip on all masses, noticeable only as their speed becomes relativistic.

At first I thought c was a barrier to the rotating universe idea, as a radius would be reached where v = c, and spoil the party. However it is clearly central to it.  This is a big relief, to consider c as a central property of the rotation rather than a barrier to it.  c is central to everything.

There are other fundamental properties of spacetime.  It is elastic, so the elasticity will have a definable value.  Yet it is also apparently unbreakable.  This links to another mystery I need an answer to – how is it that mass, which so readily converts to energy in an ordinary star (OK very slowly) or in the accretion disc around a black hole (up to 10% conversion I believe) becomes so stable once it has entered the event horizon?  The simple answer is that whether it is in mass or energy form it is still equivalent stuff that contributes to the black hole effective mass.  But energy doesn’t show properties of mass elsewhere.  Interesting things, black holes.

Words coming together

It has been difficult to discuss gravity without everyday things like rubber sheets, whirling objects on strings etc, and previous attempts to summarise used too many of these.  But I've been inspired to try again by articles in New Scientist discussing progress, or lack of it, in big physics.  This time it worked, and I am submitting an essay on the subject to the Gravity Research Foundation, March 2013. This way, it will be published only if it does well, and can be safely ignored otherwise.  At least it's a stake in the ground for me, and a reference point if I dare to request serious comments.
Just an "as if" model, but offering a way of thinking about the fundamental cause of gravity, the requirement for the fourth spatial dimension and a bit of justification for this, the expansion of the universe, dark energy, dark matter, a potential prediction for the reduction of G with time, and the reason that gravity has never been related to the three fundamental forces of nature.
But I think we can leave inflation for another time . . .

Gravity is so weak because . . ?

Having been immersed in the last few months in the complexities of quantum mechanics, and other reading including about the quantisation of space itself, it has been too easy to park the subject of gravitation.  But it has emerged in two places recently, the Horizon programme and an article of the IoP.  Apparently the reason the 4th fundamental force, Gravity, is so weak is that the world we (and the other three Forces) inhabit has only three spatial dimensions and act entirely within them, whereas gravity exists mainly in a 4th spatial dimension.  Not a macro dimension (which would contradict GR) but a micro one, too small for us to observe.  A neat analogy is that a tightrope can only be walked on in one dimension, but ants can also walk all around it.

But the line defining the x dimension is just a mathematical construct, it has no thickness or circumference.  Put an ant on a spider thread, it can rotate around it (as a man on a tightrope could), but not walk around it.

Centrifugal force is not a force, unlike the centripital force (which is a true force) required to balance it in a stable, whirling (can on a string) system.  Centrifugal force is known as a virtual or "imaginary" force, a consequence of an object with mass and hence inertia being constantly accelerated in a circular path.  Gravity is the same kind of imaginary force, such that in the case of an orbiting planet, the two imaginary forces, centrifugal and gravity, balance each other.  The object is being acted upon in two ways (a) by the elastic space it and its massive partner are being accelerated by, thereby sharing a dent in the space, and (b) by the inertia of the orbiting masses resisting the dent pulling them together.  Gravity replaces the centripetal force applied by the string.  Hence gravity and centrifugal are equivalent, the mass and its inertia affecting them both identically, but the difference is a two-dimensional shape, the circle (more generally the ellipse).  Gravity has an extra dimension S4, and it is one that we all experience.

Maybe that extra dimension is just time T, but I would rather use S4 and then determine if S4 = T.  But no need for gravity to be locked into "micro-S4" - it is not a force at all (let alone a fundamental force).

Everyone is hung up about dark matter being needed to explain why galaxies clump together as they do, and dark energy to explain why dark matter is not causing the expansion of the universe to slow down, but accelerate.  The higgson explains why matter has mass, but I wonder if it can explain how nothing can also have mass?  It is clear that dark matter can be mapped by the observation of distant objects through gravitational lensing.  But can't the lumpy shape of dark matter be modelled instead by clumpiness of space itself?  Not easy, I know.  I need dark energy, not to expand the Universe, but as the rotational potential energy in S4 with which space is whirling all the mass within it.  If I had my way, the zero of potential energy would be the bottom of the largest possible black hole, and the value at "infinity" would equal the total DE.  Though that might not be very convenient.

I am worried by the finding that the Universe is flat, and therefore infinite, as infinity is just another mathematical construct, 1/0, impossible in reality.  Seems to me they are asking the wrong question, and just ending up with the number they first thought of.  Naive, maybe, but interesting . .

Take a fresh look . .

I posted something profound the other day.  Richard Feynmann is quoted by John Gribbin as saying that if each point in space takes a huge (infinite?) amount of computing effort to describe what it is and does, then something is wrong with our understanding.  It has to be fundamentally simple.  And in a whimsical post on a forum I asked (independently) how did all those electrons learn all that maths? We do seem to be a pre-Copernican maelstrom, like  trying to make sense of planets in curly orbits around the Earth.  Whatever happened to Occam's razor?

I still wonder why physicists hope or expect to reconcile the three main forces with gravitation.  They do so because they are part of the same universe, and clearly all involved in the processes we observe, like star evolution.  But it does not follow that the container should be directly related to the contents, even in this context.

Gravitation is a feature of the shape and (I contend) motion of spacetime, whereas the strong, weak and electromagnetic forces are properties of the 'medium' of spacetime and the particles in it.  Mass is a property of some particles, and masses interact with spacetime as they resist being pulled along by it, but that does not mean that gravitation is related.  The same can be argued for radiation, that it follows the shortest path through spacetime even though it is bent by the interaction with large masses.  It doesn't "know" it is being bent.

This separation approach seems to me to be the only way to progress the explanation for dark energy and dark matter, since otherwise it makes no sense that with all our detection means and theories there is no direct evidence for either.  They have to be results of the interaction between masses and the motion of spacetime, clearly measurable only on the same large scale as relativistic effects.

I think a good new approach will be for experts to define contrary projects and spend at least 10% of their time on them.  In other words, take some of their pet theories or dogma or "facts" and try to show they are not true.  Peers will then check how honest and diligent they have been, the payoff being that a thorough honest contradiction by an expert, which fails, will properly enhance their orignal premise.  But there are bound to be some successes in the contradiction, or new ambiguities, or new pathways discovered, leading to some answers.

This may be a way for amateurs or undergrads to contribute, because they can come up with contradictory project ideas without necessarily understanding the subject to the detail of the expert.  In fact it is an area where naivity may allow a question to be asked, that an expert (or his expert rivals) would not.

Well it worked for Galileo, Copernicus, Newton, Maxwell, Schrodinger et al.  Maybe time to study alchemy . .

Not a game for amateurs

Studying physics is a broad process - as well as formal study, questions arise which lead to reading recommended material, which shows that the experts are scratching their heads.  The fact that some physicists are almost in despair that their quest for the truth appears further, not closer, indicates a huge challenge ahead.

Richard Feynmann said that if you watch a safecracker trying to crack a combination, there is no point in asking "Have you tried 10-20-30?".  Of course he has, and many others besides.  Yet it is as if science is taking a blind turn, and could be relaxing its rules of evidence to accept bizarre theories while curtailing its ability to question some of its fundamentals.

Reading of Lee Smolin and John Gribbin (I have Penrose but no time yet to read) indicates that space itself is quantised, but with enormous problems of scale; that string theory proceeds with no predictions or evidence in a closed shop; that our view of reality is subjective no matter how objective we try to be, as we use our photons and electrons to observe - photons and electrons.  SR limits to light speed, yet wave functions collapse everywhere at the same instant.

However, as I continue to have assessments to submit and exams to take, there are plenty of my original questions still to tackle.  There is no real progress on dark matter or dark energy; the subject of the number of dimensions is still apparently open, despite GR appearing to stick with 3s+t; he distinction between gravity and the other three main forces is very confused.

No answers here, but it is fun trying to understand the questions.  What a subject to be working in!

I often muse how fortunate we are to be living at a time when most of us live comfortably, have all this information and IT at our disposal, and can can probe to the smallest and largest scales in the universe.  We should be walking around in wonder at it all.  Well in a sense we are, even as we take it in our stride and press on . . .