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New Theories / Re: Evolutionary cosmology

« on: 16/10/2014 10:58:09 »

I have not visited this page for quite a long time but I have just Googled evolutionary cosmology and find it a  the top of the list.  Things have progressed quite a lot with my thinking since i posted this work and I have made several starts on a paper that I would like to see peer reviewed however I have still not got a firm idea where I should try to send it.  I note that my RAS journal  Astronomy and Geophysics occasionally publishes papers on new and speculative ideas close to the main stream of thinking so maybe that would be the proper place for it.

Anyway I must cut to the chase. 

Firstly a quick reminder about black hole collapse towards a theoretical "singularity"

The total quantity of energy released tends towards infinity.  That is even a relatively small black hole could release enough energy inside its event horizon to create a universe as large and complex as ours.  It just has to collapse far enough before quantum gravitation effects significantly change the inverse square law as happens with electromagnetic processes.  This means that even a stellar mass black hole could contain a whole universe.  It can never explode beyond its event horizon in this universe bit that does not mean that it could not create its own space time environment.

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Physics, Astronomy & Cosmology / Re: does plasma happen in soild state

« on: 04/05/2014 18:10:00 »

I agree that the answer is strictly no if you want all the characteristics of a gaseous plasma but conductors and semiconductors with mobile electrons and holes can exhibit some of the characteristics of a plasma. 

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Physics, Astronomy & Cosmology / Re: How can we define a black hole accretion zone?

« on: 04/05/2014 18:03:57 »

The original question does not have a precise answer because in the absence of any othe material the gravitational field of an object extends right out to infinity. 

You therefore have to define something else to allow you to set sime sort of size to the accretion zone.

In the case of a black hole the smallest distance friom the centre is the event horizon which is about one mile for each soar mass that the black hole contains so a typical 10 stellar mass black hole is about ten miles across which is pretty small.  The billion solar mass black holes at the centres of large elliptical galaxies are only about as big as the solar system. 

The event horizon is not really a useful limit though because that defines the smallest size that we could possibly identify. 

A more useful limit might be the point at which cold accreting gas would heat up due to the gained gravitational energy being turned into kinetic energy to glow like a star.  For a stellar mas black hole this would be approximately the size of a normal star with the same mass and colour as the temperature chosen.

This is OK for small black holes but there are no such thing as billiion solar mass stars around so there is no easy bench markfor sars of this size and the relationship is not a simple linear one like size of the event horizon. and this limit is notreally discussed in most texts however ther is one futher fact that could be used.  That is the fact that if billion solar mass lump of gas was coollapsing it is possible for it to collapse directly into a black hole without ever becoming a star and synthesising new nucleii so the maximum size of te acretion zone of a black hole is probably about the size of the solar system  which at the distance of galaxies is a pretty small thing. 

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Physics, Astronomy & Cosmology / Re: Is time scale-invariant?

« on: 01/04/2014 10:10:33 »

An interesting and difficult question alexbalex.  As with a lot of these things one could say yes as for as normal life is concerned but then say no when we stray into the quantum domain and finally maybe or maybe not! when we think a bit more about it.

Firstly let me say a bit about scale invariance.  Put simply this means that on whatever scale you look at something the larger characteristics of the thing are on the whole the same.   However different disciplines tend to stress what they mean by characteristics.  The classic physical or mathematical case is a fractal structure where a graph or a coastline has broadly a similar degree of wiggles on a wide range of scales.  In a mathematical equation (for example the Mandelbrot set) this can go on to infinity but in physical structure this can break down as the properties of a material change significantly with the scale on which you observe it.  In the case of physical laws this means that the laws apply on whatever scale you use to observe them.

Scale invariance also has a meaning in quantum theory in that the strength of the interactions between particles is the same on whatever scale these things are observed.

However when we come to think about quantum theory properly, things as always can get a bit fuzzy because quantum uncertainty come into play.  This sets clear limits on what we can observe precisely on individual experiments. We can only know what happens on the average from a large set of experiments  so at high energies, and by implication small scales details, of lower energy interactions are in effect hidden. This of course means that scale invariance may be true, but then again may not as long as the statistics is right for us "outside the box"  defined by the uncertainty limits.

Now the really important result of this is that gravitational interactions between particles are hidden way down inside this box and we could only observe gravitational interactions at vast energies way beyond any sort of energy even vaguely conceivable in a scientific experiment.  However in the very extreme conditions when a the core of a black hole is contracting inside its event horizon towards this theoretical mathematical "singularity" everything is squashed together so tightly that normal charges between positive and negatively charged particles are effectively neutralised by the extreme proximity of particles with opposing charges and the strong forces do not come into play leaving only gravity and possibly the ideas generated by the vast array of string theories to operate.  This is where the fundamental properties that define a universe are probably defined.   This may be fixed by scale invariance, things settling out "randomly" or by some sort of evolutionary or "crystallisation"  process.  This is where the quantum gravity and cosmological theoreticians meet.

Unfortunately the cosmologists do have their observational limits currently mostly associated with the cosmological microwave background which is light emitted when our whole universe was like a single exploding star and the recently published observation of polarisation due to gravitational waves on this background and possibly a future experiment that may be able to observe a cosmological neutrino background radiation.

This may be an insoluble problem but I reckon that there is a way to look at this problem but to talk more about that that would go beyond the limits of this page which is limited to currently widely accepted theories.

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Physics, Astronomy & Cosmology / Re: If the galaxy is expanding, how do you measure objects using the speed of light?

« on: 20/03/2014 23:54:12 »

You can only measure the distance to an object when the light from it has reached you the object is of course further away because of the time this takes.  this is what relativity is all about.

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Physics, Astronomy & Cosmology / Re: Why do black holes light up when feeding from a star?

« on: 20/03/2014 23:51:31 »

Black holes are in fact very difficult to fall into because they are so small.  about one mile across for  every solar mass that they contain so a typical stellar mass black hole is around 10 miles across.  The conservation of angular momentum means that falling towards a black hole unless an object is headed precisely towards it it will swing round it in a hyperbolic orbit and go  away. 

Even if a the centre of a gas cloud or star is headed precisely towards the hole most of the rest of the gas cloud or star would not be and so would miss it and go into would be compressed and heated and then distorted by the angular momentum and would get be very hot.  The orbital velocity of material going round a black hole approaches the velocity of light before the event horizon is reached so this will radiate away about half of the gravitational energy gained during falling in. 

In fact "feeding" a black hole with gas is the most efficient source of energy possible,  because it releases about 50% of the mass energy of the material.

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Physics, Astronomy & Cosmology / Re: Dynamic Casimir Effect

« on: 05/03/2014 23:21:40 »

It's all about resonances.  If you hit a particle with just the right energy to do the job it is more likely to work whereas a much higher energy particle might just zip right through.

A very good example of this is the fission reactor where U235 needs low energy neutrons to cause the fission but when it splits the excess neutrons come out with a high energy and the reactor needs a moderator that does not absorb neutrons but cools them down so they work better and the reaction can be stabilised.

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Physics, Astronomy & Cosmology / Re: Dynamic Casimir Effect

« on: 04/03/2014 18:05:59 »

sorry yor-on I was forgetting to say that if we have enough energy the interactions could include particle pairs and include the fact that if the energy was high enough massive particles could be created.

In general electrons and positrons are the lowest mass particles considered for this process but I cannot see any good reason why neutrinos or other very low mass particles should not be possible the big problem is observing the result of this sort of interaction because it would probably be very rare and the particles are extremely difficult to detect.

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Physics, Astronomy & Cosmology / Re: would the first UFOs that visit us contain life or robots?

« on: 03/03/2014 23:08:47 »

Assuming an originating life form similar to that on earth.  I think that it is highly likely tat any attempt at interstellar travel will be conducted using electronics and robotics because of its potentially much greater durability, simple environmental requirements and the ability to minimise its energy usage for very long periods.

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Physics, Astronomy & Cosmology / Re: Dynamic Casimir Effect

« on: 03/03/2014 23:01:51 »

Absolutely nothing.   In the absence of any other material very close to the two photons photons do not interact with each other.

However if there is another electromagnetic field involved photons can interact and break up into lower energy photons.

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Physics, Astronomy & Cosmology / Re: How does compactifying dimensions work?

« on: 03/02/2014 19:55:49 »

I agree that it is a difficult concept and I am not absolutely 100percent sure that I fully understand it.  I see it a bit like the way we use complex numbers to describe oscillations and waves.  After all the "dimensions" that we cannot see are complex numbers in quantum mechanics.

The compactified dimensions that we are talking about here are genuinely very small as to precisely how small they are is still open to question.  The range of some of the short range forces associated with strong and weak interactions may have something to do with their size but they may not.

The properties of particles are defined by not the position but the phase in these recycling dimensions just like where something is in an orbit.

The important result of this is that the universe is very small in these dimensions and only large in our familiar dimensions of space and time.  If you accept this the oddities of a lot of quantum mechanics disappear

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Physics, Astronomy & Cosmology / Re: Wheeler-Dewitt equation in plain english

« on: 30/01/2014 00:10:40 »

 Paros  I did not mention specifically. All wave functions are integrals over all of space AND time. Quantum theory implies that every particle in our universe exists in all of space and time.  It may however be extremely improbable to find it in very unexpected places but the probability is never absolutely zero in a mathematical sense.

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Physics, Astronomy & Cosmology / Re: How does luminosity decrease with distance from a light source?

« on: 30/01/2014 00:02:54 »

The classic inverse square law is in effect defined by the conservation of energy. For a radiating point source (zero dimensions) the energy density falls off in proportion to the increase in the area of the surface that surrounds the point.  This increases as the square of the radius that is one less than the three of the dimensions of the volume.

There is an interesting extension to this relating to the dimensionality of the source and the space that applies generally.

For normal three dimensional space the radiation fall off from a one dimensional (long line ) source falls of as the inverse of the distance and the fall off from a large plane source is zero. this can be demonstrated by visiting the empire state building.  The basic rumble of traffic noise(excluding of course very local noise sources  at street level) is the same at the top of the tower as in the street at ground level because you can hear noise originating from a much larger area of the city.

This concept also applies to world with higher numbers of spatial dimensions than three.

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Physics, Astronomy & Cosmology / Re: Why has the asteroid belt not formed a planet?

« on: 27/01/2014 15:07:07 »

I agree with clifford K's explanation roconi's is a load of garbage for far too many reasons to bother explaining

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Physics, Astronomy & Cosmology / Re: Wheeler-Dewitt equation in plain english

« on: 27/01/2014 12:44:30 »

Deep at the heart of cosmology there is this unproved and unprovable belief that the whole bulk,  that is, everything that there is not just our universe but the sum total of all universes, is a zero sum game.  That is all the disturbances wave functions etc that there are, balance themselves out to result in the concept that if there was not something (which there is) there would be nothing.

This is in effect the full extension of the well known and accepted law of the conservation of energy writ as large as possible.

It is possibly the nearest thing to the modern cosmologists view of the concept of "god" which in religions is seen as something that acts on everything to produce things.

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New Theories / Re: Is gravity a residual effect of nuclear forces?

« on: 21/12/2013 11:51:50 »

There is a suggestion that gravity is a bit like the "van der walls"  forces that hold essentially electrically neutral atoms together in compounds but the main forces are operating in the curled up dimensions of string theory and not our normal dimensions of space and time.

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New Theories / Re: New theory of dark matter.

« on: 21/12/2013 11:41:21 »

Sorry Michael your ideas cannot fit the observed facts. Current theories do although there are two main competing ones.

Administrators this entry belongs in the "new theories" area.

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Physics, Astronomy & Cosmology / Re: rotation

« on: 26/11/2013 08:54:25 »

Grimbo The answer to your question is simple.  The universe was very smooth and flowing evenly in the early stages of its existence as shown in the cosmic microwave background signal. However radiation and stellar winds from stars together with many explosions of supernovae have created turbulence in the flow of gases etc throughout the universe when these are created they do not generate any overall angular momentum (rotation) for the universe but they do generate rotation in all sorts of different directions that balances out to zero overall.  When bodies contract under gravity to form stars and galaxies there is always a small imbalance in this rotation in some "random" direction.  As the collapse progresses this rotation speeds up and becomes more visible and so all collapsed bodies rotate to a certain extent but some more than others. 

Surveys have been taken of the net speed and direction of rotation of galaxies and clusters of galaxies and currently there appears to be no clearly favoured direction overall although there are slight hints that there may be one.

It is also important to note that black holes because they are so tiny.  A black hole with the mass of the sun is one million times smaller than the sun at around one mile across! Almost all black holes must be rotating at the absolute maximum speed allowed

There is an upper limit to the amount of angular momentum energy (rotation) that a black hole of given mass can contain. Any particle that attempts to exceed this limit will not fall into it but just "bounce off" and not cross the event horizon!

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Physics, Astronomy & Cosmology / Re: In black holes, are the event horizon and the singularity one and the same?

« on: 11/11/2013 09:21:44 »

Android,  what you say is true for someone looking from outside of what is going on.  This is in fact largely irrelevant for understanding what is really going on.  What is most important is what particles and objects close together in a state of free fall are experiencing. you must remember that with the exception of the existence and effects of extreme gravity gradients locally everything always looks perfectly normal with no significant changes in local space and time except of course for the effects of normal physical changes like heating of gases due to compression etc.

I agree that looking a long way away the observable universe will change and if it changes on observable timescales it will be possible to understand what is going on.

It annoys me that people are obsessed by what is seen by outside observers as objects get close to an event horizon but do not bother to think what is happening to the particles themselves because that is where a real innovation may be found. 

OK I accept that this is all that we, as outside observers may see.  However just think, when we see a red hot poker cooling down do we marvel at the fact that it "never" reaches room temperature?  Why then should we marvel at an observable red shift as things approach an event horizon.  In reality the image would fade form visibility or detectability quite quickly and the extreme events described are not really observable.

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Physics, Astronomy & Cosmology / Re: Does the CMBR have a frame of reference?

« on: 06/11/2013 23:42:12 »

Careful measurement of the Cosmic Microwave Background Radiation (CMBR) suggests that our galaxy is moving with a velocity of 360Km/sec in the direction of Leo. This does provide a standard frame of reference however you cannot say the converse and interpret it as an absolute frame of reference with respect to some origin.

The relative motions and rotation axes of galaxies are in general random and show no preferred direction once the effects of universe expansion and local velocities have been removed