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Posted: Tue Aug 22, 2006 6:37 am
by harry
Hello All
As for Black Holes the info is on google.
I will come back to that another day.
====================================
I remember discussing the inner core or our sun and maybe that of other stars.
Here is some recent info on sun's workings. This info moves away from the standard model of the sun.
http://www.omatumr.com/papers.html
http://www.omatumr.com/abstracts2003/jf ... uidity.pdf
http://www.omatumr.com/abstracts2005/Is ... ration.pdf
http://www.omatumr.com/abstracts2006/Nu ... Cosmos.pdf
http://www.omatumr.com/abstracts2006/OC ... OCycle.pdf
Posted: Tue Aug 22, 2006 8:20 am
by harry
Hello All
Maybe I'm wrong about Black Holes, maybe Mr Skeptic knows more than I think.
Here is some info,,draw your own conclusions. What and how you think will determine the outcome.
http://www.physics.usyd.edu.au/rcfta/an ... ode10.html
This Hubble Space Telescope image of M87 (courtesy of NASA) shows the jet, emanating from the center of the galaxy, directed towards the upper right corner. A large knot is prominent (upper right) and smaller knots are discernable along the length of the jet.
http://www.seds.org/messier/more/m087_h2.html
After decades of study, prompted by these discoveries, the source of this incredible amount of energy powering the jet has become clear. Lying at the center of M87 is a supermassive object, which has swallowed up a mass equivalent to 2 billion times the mass of our Sun. This object may be a supermassive Black Hole, according to what many astronomers currently think. The jet originates in the disk of superheated gas swirling around this object and is propelled and concentrated by the intense, twisted magnetic fields trapped within this plasma. The light that we see (and the radio emission) is produced by electrons twisting along magnetic field lines in the jet, a process known as synchrotron radiation, which gives the jet its bluish tint.
M87 is one of the nearest and is the most well-studied extragalactic jet, but many others exist. Wherever such a massive central object is feeding on a particularly rich diet of disrupted stars, gas, and dust, the conditions are right for the formation of a jet. Interestingly, a similar phenomenon occurs around young stars, though at much smaller scales and energies.
COSMIC JETS
http://www.merlin.ac.uk//about/layman/jet.html
Since MERLIN began work in 1980, its images have helped shed light on the mysterious processes going on inside radio galaxies and quasars. High-resolution observations reveal that a typical radio galaxy or quasar has a bright, compact core from which issue two narrow "jets", which appear to impact on the twin lobes which have been known since the 1950s. Although not all sources show these features, it appears that the jets are transporting energy from the nucleus of the galaxy and depositing it in the lobes.
M87
http://www.seds.org/messier/more/m087_h_nrao.html
Space Telescope Science Institute astronomers and their co-investigators have gained their first glimpse of the mysterious region near a massive central object at the heart of a distant active galaxy, where a powerful stream of subatomic particles spewing outward at nearly the speed of light is formed into a beam, or jet, that then goes nearly straight for thousands of light-years. The astronomers used radio telescopes in Europe and the U.S., including the National Science Foundation's (NSF) Very Long Baseline Array (VLBA), to make the most detailed images ever of the center of the galaxy M87.
The Most Distant X-Ray Jet
http://antwrp.gsfc.nasa.gov/apod/ap031128.html
Streaming From A Black Hole
http://antwrp.gsfc.nasa.gov/apod/ap970613.html
http://hubblesite.org/newscenter/newsde ... s/1997/18/
The Hubble telescope's imaging spectrograph simultaneously records, in unprecedented detail, the velocities of hundreds of gas knots streaming at hundreds of thousands of miles per hour from the nucleus of NGC 4151, thought to house a super-massive black hole. This is the first time the velocity structure in the heart of this object, or similar objects, has been mapped so vividly this close to its central black hole.
Black Hole Blows Bubble Between The Stars
http://pda.physorg.com/lofi-news-black- ... _5756.html
The discovery means that for decades scientists have been severely underestimating how much power black holes pump back into the universe instead of merely swallowing material across their event horizons.
Jets of energy and particles flowing outwards at close to the speed of light are a common feature of all accreting black holes, ranging from supermassive black holes at the centres of active galactic nuclei to stellar-mass black holes in X-ray binary systems within our own Galaxy.
However, for the first time European astronomers have now discovered a large bubble surrounding an X-ray binary system. The bubble is approximately 10 light years across, and is predicted to be expanding with a speed of around 100 km per second (225,000 mph).
It appears to have been formed by the action of a powerful outflow or "jet" of energy and matter from the black hole over a time scale of about a million years.
The new, detailed radio observations of a black hole called Cygnus X-1 show a ring of radio emission around a bubble in the nearby interstellar gas - the result of a strong shock that develops at the location where the jet strikes the rarefied gas of the interstellar medium.
The jet that created the bubble seems to be carrying more than 100,000 times the total luminosity of our Sun, and yet the only evidence for this incredible flow of energy is its impact on the tenuous gas between the stars, resulting in the expanding bubble.
"We already knew that supermassive black holes at the centre of other galaxies produce enormous amounts of energy, but this finding proves that something similar is happening in our backyard," said Elena Gallo of the University of Amsterdam, lead author of the paper which will appear in this week's issue of Nature.
"Remarkably, it also means that, after a massive star dies and turns into a black hole, it is still capable of energising its surroundings, by means of completely different mechanisms."
"The importance of this result is that it demonstrates that black holes such as Cygnus X-1, of which there may be millions within our galaxy alone, do not swallow all of the infalling matter and energy, but rather redirect a considerable fraction of it back into space," added Rob Fender of the University of Southampton, second author on the paper.
"We knew about jets from black holes and expected to discover some interaction of the jet's energy with the gas in our Milky Way, but the size and energy content of this bubble came as a surprise," added co-author Dr. Christian Kaiser, also of the University of Southampton.
Deep X-ray surveys reveal black hole population, glimpse at the universe
http://pda.physorg.com/lofi-news-black- ... 10954.html
Mysterious quasar casts doubt on black holes
http://www.newscientistspace.com/article.ns?id=dn9620
A controversial alternative to black hole theory has been bolstered by observations of an object in the distant universe, researchers say. If their interpretation is correct, it might mean black holes do not exist and are in fact bizarre and compact balls of plasma called MECOs.
Surprising news about black holes
http://pda.physorg.com/lofi-news-black- ... _3277.html
Image Archive: Quasars, Black Holes & Active Galaxies
http://www.spacetelescope.org/images/ar ... c/quasar//
Posted: Sun Sep 03, 2006 11:56 am
by astro_uk
Just responding to a good point from BMAONE23,
As far I have always understood it gravity does travel at the speed of light. My belief in this is strengthened by all the experiments at the moment to measure gravitational waves, if grvaties speed was infinite, these experiments couldnt tell you anything, of course if it is greater than c but still finite then it should tell us somehting very interesting I would guess.
The problem that theorists have always had about gravity is simply how weak it is compared to other forces, but it is the only force that (as far we know) that is infinite in range, all other forces like the em force tend to balance out because things tend to be electrically neutral over large regions. I think a common idea now is that somehow gravity can spread through other dimensions that the other forces cannot, so it seems to be much weaker but actually is probably about the same.
Anyway all speculation there. No on really knows.
Posted: Sun Sep 03, 2006 3:35 pm
by Dr. Skeptic
Maybe I'm wrong about Black Holes, maybe Mr Skeptic knows more than I think.
Harry, you are too kind - Thank you!
Re: gravity is not a substance
Posted: Sun Sep 03, 2006 3:38 pm
by Dr. Skeptic
ta152h0 wrote:Gravity is not qa substance, it is a reaction.
![Smile :)](./images/smilies/icon_smile.gif)
That depends one which model of the universe one uses.
Posted: Wed Sep 06, 2006 8:52 pm
by Qev
astro_uk wrote:The problem that theorists have always had about gravity is simply how weak it is compared to other forces, but it is the only force that (as far we know) that is infinite in range, all other forces like the em force tend to balance out because things tend to be electrically neutral over large regions.
Just picking nits, but the electromagnetic force, since it's mediated by a massless particle, also has infinite range. Unlike gravity, however, it has two charges which serve to cancel over any significant distances.
![Smile :)](./images/smilies/icon_smile.gif)
Posted: Thu Sep 07, 2006 9:37 am
by harry
Hello All
I came across these links that maybe of interest
POSSIBLE NEW PROPERTIES OF GRAVITY
http://metaresearch.org/cosmology/gravi ... ravity.asp
You may have to read the link to get more info.
From our perspective, the Earth is standing still and the Sun is moving. So it seems natural that we see the Sun where it was 500 seconds ago, when it emitted the light now arriving. From the Sun’s perspective, the Earth is moving. It’s orbital speed is about 10-4 c, where c is the speed of light. So light from the Sun strikes the Earth from a slightly forward angle because the Earth tends to “run into” the light. The forward angle is 10-4 radians (the ratio of Earth’s speed to light speed), which is 20 arc seconds, the same displacement angle as in the first perspective. This displacement angle is called aberration, and it is due entirely to the finite speed of light. Note that aberration is a classical effect, not a relativistic one. Frame contraction and time dilation effects are four orders of magnitude smaller, since they are proportional to the square of the ratio of speeds.
Figure 1
Now we naturally expect that gravity should behave similarly to light. Viewing gravity as a force that propagates from Sun to Earth, the Sun’s gravity should appear to emanate from the position the Sun occupied when the gravity now arriving left the Sun. From the Sun’s perspective, the Earth should “run into” the gravitational force, making it appear to come from a slightly forward angle equal to the ratio of the Earth’s orbital speed to the speed of gravity propagation.
This slightly forward angle will tend to accelerate the Earth, since it is an attractive force that does not depend on the mass of the affected body. Such an effect is observed in the case of the pressure of sunlight, which of course does depend on the mass of the affected body. The slightly forward angle for the arrival of light produces a deceleration of the bodies it impacts, since light pressure is a repulsive force. Bodies small enough to notice, such as dust particles, tend to spiral into the Sun as a consequence of this deceleration, which in turn is caused by the finite speed of light. This whole process is called the Poynting-Robertson effect.
But observations indicate that none of this happens in the case of gravity! There is no detectable delay for the propagation of gravity from Sun to Earth. The direction of the Sun’s gravitational force is toward its true, instantaneous position, not toward a retarded position, to the full accuracy of observations. And no perceptible change in the Earth’s mean orbital speed has yet been detected, even though the effect of a finite speed of gravity is cumulative over time. Gravity has no perceptible aberration, and no Poynting-Robertson effect – the primary indicators of its propagation speed. Indeed, Newtonian gravity explicitly assumes that gravity propagates with infinite speed.
The Speed of Gravity – What the Experiments Say
http://metaresearch.org/cosmology/speed_of_gravity.asp
You may need to read it,,,,,,,,,posting it has left many items out.
Conclusion: The Speed of Gravity is ³ 2x10^10 c
We conclude that gravitational fields, even “static” ones, continually regenerate through entities that must propagate at some very high speed, . We call this the speed of gravity. Equation [1] then tells us how orbits will expand in response to this large but finite propagation speed, since the field itself, and not merely changes in the field, will transfer momentum to orbiting target bodies. Rewriting equation [1] in a form suitable for comparisons with observations, we derive:
[5]
For the Earth’s orbit, = 1 year, = 10^-4, and we take as an upper limit to the value 2.4x10^-12/year (derived from ½ ) in solutions using radar ranging and spacecraft data (Pitjeva, 1993). Substituting these values, we get from Earth-orbit data that ³ 10^9 c.
Using the same equation with binary pulsar PSR1534+12 and the parameters in Table I, we can place the most stringent limit yet from the observed uncertainty in : ³ 2x10^10 c.
A direct experimental verification in the laboratory that gravity propagates faster than light may now be possible. The protocol and preliminary results were reported in (Walker, 1997).
It might be tempting to conclude that the speed of gravity is infinite. But these limits on are still a long way from infinite velocity, and Newton’s statement, quoted at the beginning of this paper, still seems applicable. Infinite speeds, too, are acausal.
Does Gravity Have Inertia?
http://metaresearch.org/cosmology/gravi ... nertia.asp
Abstract. » Gravity makes heavy and light bodies fall at the same rate. Gravity obeys the “equivalence principle”, and is just "curved space-time geometry" in geometric general relativity. But space-time curvature alone cannot initiate motion, and changes in momentum still require a force acting. Moreover, gravity can deviate slightly from the “equivalence principle”, and “space-time” is really just proper time and does not involve any curvature of space. The Le Sage “pushing gravity” concept is a better way to explain the physics of gravity. For forces other than gravity, the momentum transferred must be shared by all particles in the target body, producing what we call “inertia” -- a simple dilution of momentum. Gravity obeys the “transparency principle”, allowing momentum to be transferred directly to each particle. Without need for dilution of momentum, gravity has no inertia. «
The above needs more proof, other papers say that the speed of gravity is at the speed of light.
Posted: Thu Sep 07, 2006 9:52 am
by astro_uk
Hi Qev
I think that is what I said.
From a practical point of view, only gravity has infinite range.
Posted: Thu Sep 07, 2006 10:27 am
by harry
Hello All
If gravity has curvature than infinity is out of the question.
If I'm wrong and gravity is infinite so is the parts within the universe.
Just thinking aloud.
Posted: Thu Sep 07, 2006 8:41 pm
by Dr. Skeptic
The gravity effect is ∞ only to the conclusion of space/time.
Posted: Fri Sep 08, 2006 8:40 am
by harry
Hello Dr Skeptic
Please explain, what do you mean.
Posted: Fri Sep 08, 2006 8:53 am
by astro_uk
Hi Harry
I think he means that as gravity is due to a property of space/time, i.e. its bending, then gravity can only be felt within space/time. So if the Universe is finite, then gravity only works as far as the "end" of space/time.
An extra comment on my earlier post about gravity being the only practically infinite force, another way to look at why this is: is because gravity unlike EM is purely attractive (as far as we know), so there is no mechanism in which gravity would tend to cancel out. Whereas of course in em, opposite charges attract and like ones repel and it becomes very hard to separate positive from negative over large distances.
Posted: Fri Sep 08, 2006 1:11 pm
by Dr. Skeptic
astro_uk wrote:Hi Harry
I think he means that as gravity is due to a property of space/time, i.e. its bending, then gravity can only be felt within space/time. So if the Universe is finite, then gravity only works as far as the "end" of space/time.
An extra comment on my earlier post about gravity being the only practically infinite force, another way to look at why this is: is because gravity unlike EM is purely attractive (as far as we know), so there is no mechanism in which gravity would tend to cancel out. Whereas of course in em, opposite charges attract and like ones repel and it becomes very hard to separate positive from negative over large distances.
Thanks _uk.
... Or, space/time is is a derivative of mass induced gravity.
Posted: Sun Sep 10, 2006 4:30 am
by harry
Hello All
If gravity is only attractive, how do you explain, the north and south pole.
Posted: Sun Sep 10, 2006 8:26 am
by astro_uk
If gravity is only attractive, how do you explain, the north and south pole.
I dont understand your point Harry, are you saying that things at the North and South poles are repelled by gravity? Im pretty sure exporers at the poles arent flung off into space.
Or maybe your making a point about magnetism?
Posted: Sun Sep 10, 2006 2:51 pm
by Dr. Skeptic
Time and gravity are open looped forces (string theory) or closed loop forces (m-Theory), the reverse effect is a product that fall into one of the other seven dimensions undetectable/unmeasurable by today's tools.
Posted: Tue Sep 12, 2006 8:38 am
by harry
Dr Skeptic
I'm just wandering where you get these ides from.
You say it with meaning.
Time is not a force.
Posted: Tue Sep 12, 2006 8:52 am
by harry
Hello BMAONE
Thanks mate, steve will be missed. The land of ozzzzzz has been left in shock.
Posted: Tue Sep 12, 2006 12:20 pm
by Dr. Skeptic
harry wrote:Dr Skeptic
I'm just wandering where you get these ides from.
You say it with meaning.
Time is not a force.
Isn't it?
Relative time can be changed by applying a force to an object and is a factor in conservation of energy (near c). Delta rT is a variable in such equations.
Posted: Tue Sep 12, 2006 2:19 pm
by Martin
What I don’t understand is why the BB is described as a finite starting point for our universe. Is there direct evidence that suggests that there can be only one bang or are we assuming this? Perhaps the conditions that caused the “recent” big bang were seeded by other events. I am not saying that I agree with Harry but I think the answer lies somewhere in between. Multiple bangs could be just as feasible, right?
If theories suggest that the BB was the start of space/time and all observable matter then my question is -what is space/time contained “in”? An expansion of space and matter has to be contained or enclosed within something –right?
Posted: Tue Sep 12, 2006 2:33 pm
by astro_uk
Hi Martin
The reason the BB gets treated as a finite starting point is because essentially it is. If time and space began at that point, we can't know anything about what came before, so anything that happens before the BB is educated guess work at best, you have to make an assumption that the same laws of physics apply before space and time, which is a not neccessarily true.
Space/time is not necessarily contained in anything. It merely is, there is nothing outside. This is the sort of area where humans run into problems, we just can't visualise what this actually means, we are used to everyday experiences that don't prepare us for the concept of nothing. Of course in various theories it could be contained in other Universes, which raises the possibility that their influence could be felt, like through gravity which is anomalously weak compared to the other forces, it could be that gravity can actually stream into these other dimensions and other forces can't so it appears as if gravity is much weaker.
I still want to know what Harry meant about gravity at the poles. Any ideas?
Posted: Tue Sep 12, 2006 4:00 pm
by Martin
Ok I can understand that but this still raises flags with my thought process.
1. Why does the BB have to be the start of space/time? Why can't the BB just be the start of energy and matter expanding within space?
2. Nothing is something isn't it? Nothing is just a term to describe the "lack of" something isn't it?
3. Why can't space be infinite and matter and energy be finite?
I'm still racking my brain on how the poles are relative to gravity!
![Shocked :shock:](./images/smilies/icon_eek.gif)
Posted: Tue Sep 12, 2006 4:38 pm
by astro_uk
In answer to 1. If the BB started as a singularity (or at least a pretty damn good approximation of one) then I believe GR and all known physics essentially breaks down, our definitions of space and time no longer have any meaning. This means that we cannot use these theories to probe what happens before the singularity.
2. Nothing usually means an absence of something in common parlance, but in this sense it litterally means nothing at all, no space, no time. Again this may simply be because all the laws of physics as we understand them have no meaning outside of the space/time that define them.
3. This idea runs into the same problems that always crop up with infinities. If this was the case, the distribution of matter would have to be very non-uniform in fact it would have to be infinitely non random just for anything to exist. Think of it this way: in an infinte Universe, if you dont have infinite matter how come the matter isnt infinitely spread out? In other words it would seem as if the Universe was empty, for any amount of matter less than infinite. Unless we live in a Universe that is pathological, and all of the matter just happens to exist just around us, with infinite stretches of nothing around us.
I do hope to hear Harrys poles theory.
Posted: Tue Sep 12, 2006 4:45 pm
by BMAONE23
Harry,
I believe the difference is in Polar magnetics vs gravity. Magnetism, north - south poles, is similar to an electric charge flowing between positive and negative poles in that it is attracted by its opposite. Gravity is a product of mass/density. The density vs mass of an object will determine it's net effect of spacial distortion expressed in terms of gravity which isn't polar specific.
Posted: Tue Sep 12, 2006 5:18 pm
by Martin
Ok now were getting somewhere.
You wrote: "The distribution of matter would have to be very non-uniform in fact it would have to be infinitely non random just for anything to exist". -Please explain!
Isn’t it true that we can only observe a limited distance into space? We have no knowledge of what exist beyond that. I cannot accept that if we could travel to the most distant point of light we would find a great barrier of nothingness beyond it. Where did this concept come from?
I can accept that there might be no more matter (as we know it) beyond that point but I can't accept -a non existent universe beyond that point. You say pathological but isn't that exactly what we observe. Observable matter does in fact just exist around the BB/us. And what we see is, in fact, "stretches of nothingness" (90%) and "observable matter" (10%) -right?
I imagine an infinite universe wherein a Big Bang occurred and energy transforms into matter and that mass of matter expands and keeps expanding. But the mass lies within an already existent universe. Why does the Big Bang imply that it created space/time? Why is that eternal relationship implied and is it that hard to separate them so that one does not imply the birth of the other?