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RECENT POSTS IN THIS TOPIC

Christian Corda: on 6/16/10 at 7:12am UTC, wrote Dears Jody and Jason, you can find the paper here: ...

Christian Corda: on 6/10/10 at 10:29am UTC, wrote Dear Scott, dears all, you could be interested that, together with my...

Jody Fulford: on 5/20/10 at 8:16am UTC, wrote I would be interested as I have ideas along those lines as well. Tell me a...

Jason Wolfe: on 5/16/10 at 22:19pm UTC, wrote Would anybody here be interested in discussing a plausible 5th force that...

Lawrence B. Crowell: on 2/8/10 at 17:35pm UTC, wrote The holographic principle and black hole complementarity so far does not...

Steve Dufourny: on 2/8/10 at 11:30am UTC, wrote Hi all, Dear Lawrence, here is my point of vue. This singularity and...

GOW: on 2/8/10 at 4:47am UTC, wrote Speaking of black holes, check out: ...

Eckard Blumschein: on 2/7/10 at 13:01pm UTC, wrote Perhaps Amir Aczel also got aware of the discrepancy between Dedekind's...



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November 24, 2017

ARTICLE: Classic Article: Building a Better Black Hole [back to article]
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General Omar Windbottom wrote on Jan. 30, 2010 @ 06:54 GMT
"Of course, Crane continues, to do so, we’ll need armies of self-replicating space robots and focusing lasers the size of an asteroid. "I haven’t spent a lot of time on the engineering," Crane concedes. "It would be very tricky."

Hmmm, I did not think fantasy took much time or effort.

OW

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Eckard Blumschein replied on Jan. 30, 2010 @ 13:58 GMT
I mention James Gregory, the inventor of the reflective telescope, of infinite series representation for trigonometric functions and of Taylor series before Taylor in contrast to those who will perhaps turn out more amusing than influential.

My aim is not hurting anybody but to find out where mathematics seriously lost contact to reality.

Ordinary people are saying: Mathematics is if first there are tree people in a room, then five of them left it and finally therefore two have to come in in order to make it an empty one. I do not consider the question what allowed and what stimulated the extraordinary progress of mathematics in the 17th century, and what foundational mistakes were possibly made, in particular in the epoch between Gauss and Hilbert.

Eckard Blumschein

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Eckard Blumschein wrote on Jan. 30, 2010 @ 18:28 GMT
Hopefully Luis Crane himself of one of those who are fostering him is able and willing to answer what I consider worth to put in question:

Is there really room for singularities in reality if mathematics returns to the idea of a genuine continuum every part of which has parts while points do not have parts?

Do not get me wrong. In contrast to G. Cantor I am not insane. I love using singularities as tools that approximate a continuum as good as we desire. However, I am arguing that in case of a discontinuity we need not to ascribe a value f(x) exactly to x. Why not using the limit to the left (-->x) instead?

Well, if there is no singularity in reality, are then antiworlds? Let me reply: I am waiting with a grin for the first black hole made in Swiss by the LHC.

I am unhappy because FQXi appreciated essays which are trying to excuse with technical difficulties the obvious failure to create quantum computers and warp drives. I would prefer a more humble honest admission of possible failures in the very basics as a starting point to solid progress.

Eckard Blumschein

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Lawrence B. Crowell wrote on Jan. 31, 2010 @ 16:03 GMT
L. Crane’s scheme involves taking light energy from enormous solar panels and concentrating it into gamma rays. That is possible, but you run into scaling issues and limitation. Those gamma photons would have to have an energy in the TeV range, or equivalently the pulse needs a temperature of about 10^20K. Anything less will concentrate photons with too large a wavelength to do the trick. This means the shell which produces gamma rays would have to be a nearly continuous distribution of LHC energy scale lasers! In fact at a million metric tons, which would be the mass-energy of this grand pulse of gamma rays, this would require over a million billion billion times the beam flux (or imploding wave flux) of gamma rays than what the LHC delivers. This would be one hell of a machine!

Besides the solar arrays being large, consider the size of the energy storage system. it would have to hold a million metric tons in mass equivalent of energy. Clearly the storage system would be many orders of magnitude larger in mass. Then to pulse it right that energy would have to charge up a Marx bank or something. That would have to be utterly huge to prevent the colossal charge stored up from tearing it apart. Imagine the enormous size of this system! This thing would be the size of Ceres, or something comparable.

I would prefer th the winner had been someone who wrote about renormalization group and conformal scaling of fields with respect to black hole amplitudes in the sorts of physics we can do now. The Brookhaven Relativistic High-energy Ion Collider (RHIC), has found channel production for small amplitudes that are similar to what is expected for a black hole. So these experiments slam gold nuclei together in the GeV range. The protons and neutrons transition into a plasma of quarks the QCD gauge particles called gluons. This then give by AdS/CFT a soft black hole probability amplitude, and evidence for this is seen by the RHIC as indicated in the referenced paper here, and data corresponding to black hole physics has also been measured . So we may be seeing hints of this sort of physics.

I have frankly jaded opinions about mega-schemes and gigantic programs --- I prefer to see small or modest ideas and technologies which have some elegance to them. This idea is a sledgehammer, more in line with science fiction. Oh well, I suppose it is not completely out of line with ideas of space elevators. Congress is not going to authorize funding for either any time in the near future.

Cheers LC

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Lev Goldfarb wrote on Feb. 1, 2010 @ 15:38 GMT
Since I'm not a physicist by profession, I have a simple question about black holes.

Is there a definitive evidence about the existence of black holes *as we (formally) understand them right now*?

Because if we don't, isn't it too premature to put too much weight on the many theoretical implications deduced on the basis of the current theory? (simply because the underlying theory may need to be radically modified)

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Lawrence B. Crowell replied on Feb. 1, 2010 @ 17:32 GMT
There is tons of evidence for black holes as generically described by general relativity. One example is from the UCLA Galactic Center Group which has observed and computed the orbits of stars around the black hole in the galaxy center. The second level of text boxes has on the right a section with oribts of these stars. Clicking on tht will reveal these orbits.

Cheers LC

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Anonymous replied on Feb. 1, 2010 @ 18:13 GMT
Lawrence,

Thanks! However, I'm afraid you missed my emphasis on "*as we (formally) understand them right now*".

I understand that there are objects in a galaxy that behave in some way 'similar' to what we call 'black holes'. That wasn't my question though! How good is the evidence that supports our (exact) formal understanding of them?

this post was moved here from a different topic

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Eckard Blumschein replied on Feb. 2, 2010 @ 12:35 GMT
Strong words like 'tons of evidence' often indicate weak arguments. I would like seconding Lev Goldfarb by quoting from Zeh, 4th ed. p. 135: "non-relativistic black holes were discussed as early as 1795 by Laplace and even before him by J. Mitchel." While I never dealt with black holes, I vaguely recall an expert who told us that there are thousands of observed candidates that largely fit to the expected properties. They do not have hairs, and some size-related details also proved unexpected.

The main reason for me to question not just white holes but also the presently mandatory theory is that taking future spacetime for granted would anticipate all future. To my knowledge there is no observed case in cosmos that could be interpreted as an indication of claimed time-symmetry. There is presumably no motion backward in time. At least there is - to my humble knowledge - no spiral motion toward a center.

A second reason for me is my doubt that singularities exist in reality. I see them merely as imagined tools as are area, line, and point. All singularities I have been using do not really have exact correlates in nature. You can describe two streets crossing at a point. In reality, such point does not exist. It belongs to an abstraction. Streets are no lines.

Eckard Blumschein

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Lev Goldfarb wrote on Feb. 1, 2010 @ 18:14 GMT
Sorry, I forgot to sign.

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Lawrence B. Crowell replied on Feb. 2, 2010 @ 03:06 GMT
Black holes have no solid surface, and stellar mass black holes have no signature of a solid surface, such as with neutron stars. Lens-Thirring effects expected near black holes have been detected. There are an array of observed aspect to these bodies to think they are indeed black holes as predicted by general relativity.

LC

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paul valletta wrote on Feb. 4, 2010 @ 10:48 GMT
I almost theorized that one could condense the Black_hole's horizon down to a (quazar), quantum laser size, then by pointing it at another planet, one could gravitate/drag?.. that planet twoards us, us being at a specific location at the said Black Hole, why go to places in the Universe if you could fetch them here? there were some deep technical problems of course!

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Eckard Blumschein wrote on Feb. 7, 2010 @ 13:01 GMT
Perhaps Amir Aczel also got aware of the discrepancy between Dedekind's meanwhile mandatory interpretation of numbers points and the traditional and still reasonable one as measure. I have to find out why he did not arrive at some due consequences.

Let me reiterate my suspicion that singularities, negative items, imaginary items, and the like alway belong to an abstracted model but never to reality. Aren't I, aren't also you obliged to carefully treat and correctly interpret them?

Does not lacking care possibly cause artifacts up to white holes? I got angry when e.g. Karrenberg tried to physically interpret negative frequencies.

Eckard Blumschein

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GOW wrote on Feb. 8, 2010 @ 04:47 GMT
Speaking of black holes, check out:

http://arxiv.org/ftp/arxiv/papers/1002/1002.1078.pdf

for something quite different!

OW

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Jason Wolfe wrote on May. 16, 2010 @ 22:19 GMT
Would anybody here be interested in discussing a plausible 5th force that would make interstellar travel fast, safe and energetically abundant?

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Jody Fulford replied on May. 20, 2010 @ 08:16 GMT
I would be interested as I have ideas along those lines as well. Tell me a little about it jodywysteria@yahoo.com

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Christian Corda wrote on Jun. 10, 2010 @ 10:29 GMT
Dear Scott, dears all,

you could be interested that, together with my colleague Herman Mosquera Cuesta, I recently found an exact solution to Einstein field equation which remove black holes singularity at the classical level, i.e. WITHOUT quantum argumentations. In our work, we have also given a new integration of the famous Oppenheimer-Volkoff Equation for the gravitational collapse.

The paper has been accepted for publication in Mod. Phys. Lett.A.

You can find the pre-print in http://arxiv.org/abs/0905.3298

Cheers,

Ch.

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Christian Corda wrote on Jun. 16, 2010 @ 07:12 GMT
Dears Jody and Jason,

you can find the paper here:

http://arxiv.org/abs/0905.3298

Cheers,

Ch.

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