BJC

Yes - every lecture i have heard or read emphasizes your point regarding the "singularity" However, I was asking if there could be similarities outside the event horizon of a black hole.

The statement in the original topic "Why not just take a logical step back and conclude that a black hole, and its core, is simply a very large, dense neutron star!" deserves a better answer than "we need quantum gravity". While it is true that no one knows "for certain" what occurs behind the event horizon of a black hole surely what happens some distance from the event horizon must be gravitationally similar to what happens to any object at the same distance (and equal mass). Say we are a distance 200 million km. from a mass of about 3 solar masses. Would it matter gravitationally whether that mass was a gas, star, neutron star or a black hole? Now consider the mass to be a black hole and we slowly decrease our distance to about the same distance as the radius of a similar mass neutron star. Wouldn't we experience the same gravitational forces as an object on the surface of a same mass neutron star? Is there a distance from the black hole where the protons and electrons form neutrons? Why is a Black Hole considered "cold" when in-falling objects must be heated by gravitational tidal forces? Wouldn't those same forces cause the temperature to be very high very close to the black hole?

some questions: 1) If the information is not lost but stored on the event horizon surface of the Black Hole --- then what is falling into the black hole? 2) As an object falls gravitationally that object becomes squeezed and accelerated. Both effects cause the object to increase in temperature. Since a Black Hole is aa massive gravitational object then objects should heat up , the Black Hole should heat up --- so why is a Black Hole so "cold" or more precisely why is the Hawking temperature so low. Susskind discussed this in his Topics in String Theory (lecture 5 and 6) but i am still unclear on the negative gravitational energy. I also assume Susskind discussed this in his lectures on Black Holes and Holography (Perimeter Institute, Lecture Series C07003) in addition to his popular book "The Black Hole Wars"

I think all (most?) physics theories do not define time or space - only whether time & space can be measured. For us to measure time or space matter is required. I am unsure of what you mean by "logically allow" As the Big Bang makes no statement about what existed prior to the "zero point" there cannot be a "logically derivation" of anything prior to that point.

Interesting - i would assume the "simplest but not too simple" would apply to the Big Bang model (+roll inflation). I read a pro-con about "galactic strings" but it was in relation to the red-shift expansion not the CMBR. Without expansion from the Big Bang it is very difficult to explain the very close fit to a black body - we will see when data from Planck is complete. BTW - i am trying to find info on early star formation and the Cosmic Infra-red background - any hints???

This was what i was referring to when i asked about "Do you deliberately vary the alignment". The reference to the "PACS Observer's Manual" is very helpful - answers many of my questions. Similar to eliminating power line (60 hertz) interference in seismic processing???

Hi Pantheory Does the current interpretation of the CMBR anisotropies "shed any light (sic)" on this topic? Our Universe May Be a 'Multiverse Probably not as this refers to the Inflation bubbles not to the pre-Big Bang interpretation given by Penrose. Interesting to speculate "Will the Planck results resolve the various interpretations of the anisotropies - or just further entrench opinions?" Edited to correct spelling.

Thank You - you are replying to my ill-formed questions with well-formed answers. I like the page Herschel First Results Symposium The Hershel site contains a lot of data - perhaps too much detail for me. Difficult to find answers to questions such as: "Is there earlier limits on initial star formation?" ; "Cosmic Infra-red Background"; etc. Again Thank You for your explanations. BTW - How do they eliminate the effect of the mirror?

Good grief - what garbage!!!!!!!!!!! What physics course did you learn this stuff from??? - You should ask for your money back.

Yes, the alignment of three instruments - but more the alignments of a single instrument for a time exposure on a specific target. A very good answer, Thank You. Explains why there is such a long "processing time" :) I suppose the raw images are not particularly useful for cosmological interpretations - which means that data processing is not only necessary but can affect theories. The process seems similar to the problems we encountered with processing 3-D geophysical seismic off-shore surveys - although i suspect we relied more on data redundancy. Do you deliberately vary the alignment to allow the processing to identify and eliminate local (solar and galaxy) rotational and movement variations?

Interesting study: On page 6: "Order of Magnitude Estimates" the authors give an estimate of gravitational attraction to expansion. Inside Solar system 1040 higher; inside a galaxy is 1011 times stronger, between galaxy clusters is still 107 times stronger than expansion. Could mean one of two things: (1)expansion occurs even in galaxy clusters but is far too small to detect (likely) or (2)expansion occurs in space quanta (unlikely - but more interesting).

I think Rolando is referring to this paper; found on the website ( http://www.marmet.org/louis/ ) This is the title and abstract taken from the "mechanisms.pdf" Looks, at first glance, to be well written. Each of the 52 "mechanisms" is briefly discussed with the mathematics and limitations. edited to add: the PDF is difficult to search - i would have preferred to have the .ps file. Marmet appears to have used fixed font spacing to align sentences which makes searching difficult: viz. "cosmic" could be "co smic" or "cosm ic", etc.

What are the technical problems (overview) of alignment that allows images from the various cameras to be synchronized? With the Hubble i had listened to a brief talk on the "dither and drizzle" problems encountered when they obtained their million second exposure for the Hubble Deep Sky survey. Is there problems matching the infrared frequencies? To other telescope images? Sorry for the rather general question - i do not know enough about the operations of telescopes to ask specific questions.

Backreaction Running Coupling Constants is one of the easiest explanations of running coupling constants, super symmetry, etc. Also i think the SUSY Unification scale is several orders larger than the Planck scale.

This is not the link to the Italian DAMA/LIBRA experiment but this link provides a possible verification of the result Dark Energy There is also the possibility that ordinary gravity repels antimatter. This could possible be tested at the CERN ALPHA experiment:

An external observer will never see an infalling observer cross the event horizon of a black hole - instead the infalling observer will appear to be stationary above the event horizon forever. But how does the infalling observer see the external observer??? I contend that the infalling observer will see the external observer normally - just the way any observer would see another in somewhat flat space. Until the infalling observer crosses the event horizon and then all contact is lost.

That is a philosophical answer. Classical (Newtonian) physics, special relativity, quantum mechanics, etc. all postulate the existence of space and time. General Relativity postulates the existence of matter (mass, energy) and derives space and time - but we always use derived metrics which presuppose Minkowski space-time. It seems physics theories require space and time to exist --- so the question "where does it exist in?" is a reasonable question --- and it is reasonable to assume that the "universe exists in this space-time" ??? :(

I do not think his philosophy differs from other quantum level theories (i.e. string theory), that is, our classical and quantum physics emerges from lower level theories. Max Tegmark ( The Universes of Max Tegmark ) has an interesting mathematical view of theoretical universes. One thing that puzzles me is: The quantum world is consistently stated as being fundamentally different from the classical world; We use classical concepts of time, space, etc. to (mathematically) describe the quantum world; Maybe our methods are the cause of "uncertainty", "wave-particle duality", etc. ??? A possible analogy could be using the integers to describe irrational or transcendental numbers. At some level you will encounter paradoxical infinities. Not sure if i am describing this very well. Probably does not belong in this topic, maybe not in cosmology.

This short (23:09) YouTube video explains his basic ideas. A more detailed (mathematical) explanation can be found at the Perimeter Institute where Barbour gives a description of his "best matching". Of interest is his derivation (reduction to) General & Special Relativity, I found this talk a bit difficult to follow, for instance at time ~59:00 of the talk he describes why light has a certain velocity: Getting back to your points: He asserts that both time and motion are "our artifacts"; thus your statement "where time accordingly seems to be solely the change between two instances" would not reflect his premise. To Barbour the two instances are just that, two instances. Our connecting or sequencing the two instances creates the illusion of change and/or time. I suspect Entropy, in Barbour's premise, would be the ratios between the many "not-so-best matching" to the "best matching"

Thank you. Difficult at times to relate, especially when the comments are a "conversation between two people". I understand Hoyle et.al. made one last attempt to retain the steady state model by introducing very small amounts of material to maintain the average density ----------------------------------- I have been trying to understand Julian Barbour the bold comments are mine. I am not sure how to formulate entropy incorporating only change - especially in the sense that Barbour uses the concept of change.

I was attempting to understand your post of (pantheory, on 4 July 2011 - 11:26 AM) not making any assertion of my own. What then were you trying to say:

"Instead what we see is generally the same density in the distant universe as we see locally. What we see is that no matter how distant we look the universe seems to be of the same density that we can see in our local neighborhood which seems totally contrary to the BB model. This problem with the standard model is rarely discussed but when it is, the explanations seem totally contrived and unconvincing" Are you trying to say that the density of the universe has never changed with time? Does that imply the density at (say) +200,000 years is the same as (say) +13. billion years?

Could someone explain the ground state of a free electron. I came across this comment: Free electrons are discussed in solar flares, in cosmology "first light", and in statistical mechanics - but i have not read any discussion of what the ground state of a single free electron means. Does your statement "... a system does" imply that a single free electron cannot have a ground state? If a free electron can have a ground state, how do they experimentally determine such a value? How is the electron momentum handled?

Easily one trillion, closer to 4 trillion or about the temperature of a quark-gluon plasma. Not Planck length - that temperature would be >> 1026 K.

Thanks to both. There does not appear to be any basic disagreement although i am intrigued by "pantheory's own theory/opinions". I would think any answer to "where does space end?" must consider conditions prior to the Big Bang. If the inflationary model is considered then vacuum energy existed prior to the Big Bang which implies space but no time (whatever time is!!) Vacuum energy has a constant energy density - does this imply a constant space field. Would this field be infinite? Does infinity even have a meaning when discussing a constant static energy field? Dark Energy Wiki Inflation (cosmology) Wiki