light between the galaxies

Chipper Q
Chipper Q
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Just found a database of

Just found a database of astronomical catalogs – the CATS database - tremendous amount of data from catalogs covering bright sources, galactic plane sources, also multi-frequency catalogs, and RATAN studies. I think I meant to say 'esoteric' instead of 'idiosyncratic' (above), and the following quote from the CATS description page helps illustrate:

Quote:
All astronomical catalogs have a different format and list different observables. It has been a major challenge to provide uniform access to such a heterogeneous collection of data sets based on different methods, using different notations and units (in the absence of a ``standard'' to create catalogs). To satisfy the different needs of users we provide the result of searches through ALL catalogs in two different ways: one is an ordered table with the same basic data from the various catalogues in a homogenized format, while the other provides the result in the native format of each catalogue, listing all the orginally published data columns.


From there, I found SIMBAD - Set of Identifications, Measurements, and Bibliography for Astronomical Data. For objects beyond the Milky Way, there's NED, the NASA/IPAC Extragalactic Database. For solar system and planetary data, there's NASA's Planetary Data System

I guess SIMBAD would be the one to use for finding visible stars in our galaxy having highly elliptical orbits – looking forward to trying to see what I can see...

Tom Awtry
Tom Awtry
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Chipper Q – Thanks much for

Message 17190 in response to message 17189

Chipper Q – Thanks much for the reference links, be assured they’ll be looked over and Bookmarked. In return, I offer the following for re-payment:

Hipparcos/Tycho catalogue home-page

Interactive Extra-solar Planets Catalog

Take Care,
Tom

Chipper Q
Chipper Q
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Thanks, Tom – ditto on the

Thanks, Tom – ditto on the bookmarking! And hats off to Mark on authoring such a helpful and informative thread – if I may speak figuratively, there's quite a lot of 'light between the galaxies', with humanity shedding more there every day...

MarkF
MarkF
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Lost & Found Dark Matter in

Lost & Found Dark Matter in Elliptical Galaxies
This link relates to question of star in highly elongated orbits. The main point being that such objects would cause an underestimation of the amount of dark matter.

Chipper Q
Chipper Q
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RE: Lost & Found Dark

Message 17193 in response to message 17192

Quote:
Lost & Found Dark Matter in Elliptical Galaxies
This link relates to question of star in highly elongated orbits. The main point being that such objects would cause an underestimation of the amount of dark matter.


It's good to see that merger simulations are in line with different observations, and it's gratifying to see that radial orbits happen during both major and minor mergers, and are even independent of the progenitor mass ratio. Staggering number of factors it is, that must be taken into account as galactic mergers evolve, from the dark matter to gas quantities to bulge sizes, from new star formation to SNRs and PN.

While the simulations are useful for density profiles of the dark matter, they of course don't address the nature of it, and I happened to be studying this letter when you made your post: Will we observe black holes at the LHC?

Planck-sized black hole remnants make a lot of sense. They would have mass. They would be displaced by baryonic, leptonic, and photonic matter, thus forming a halo. And I'm guessing that they would be responsible for what we observe in a 'vacuum'. Am I missing something?

MarkF
MarkF
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RE: Planck-sized black

Quote:
Planck-sized black hole remnants make a lot of sense. They would have mass. They would be displaced by baryonic, leptonic, and photonic matter, thus forming a halo. And I'm guessing that they would be responsible for what we observe in a 'vacuum'.


Your guess is as good as mine, however if Hawking radition is real then Plank black holes would evaporate fairly quickly.

Chipper Q
Chipper Q
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RE: however if Hawking

Quote:
however if Hawking radition is real then Plank black holes would evaporate fairly quickly


I think this relates the discussion (in this thread) about which physical constants are more fundamental than others; those with units, or dimensions, are all based on those referred to as dimensionless numbers. Is it correct to say that there is nothing “uncertain” about the Planck-length? If so, then a horizon radius within that length has no meaning, true? Or phrased another way, if something could be confined within the Planck-length, wouldn't it have infinite momentum (based on the certainty of position)?

I notice that uncertainty in QM has the same status as invariance in GR, insofar as they're both principles. So now I wonder which is more fundamental, principles or dimensionless numbers? It's interesting how a generalized uncertainty principle leads to an even hotter quantum BH than a semiclassical one (with the same mass), and it would be even shorter-lived, since the GUP-corrected mass loss is larger than the standard Hawking mass loss.

Is a 'principle', then, properly referred to as an 'operator'? Can it be referred to as a 'mechanism'? For example, since it is the standard uncertainty principle that keeps the hydrogen atom from collapsing, is there any other mechanism to which this stability may be attributed?

MarkF
MarkF
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The plank units for time,

The plank units for time, length, mass and temperature are derived by putting the speed of light, Plank’s constant, Newton’s gradational constant and Boltzmann’s constant all equal to one. This is no different than switching from MKS to CGS. Setting all the constants equal to 1 simplifies the equations that rely on them but you must the same transformations to experimental results. All the uncertainties about the values and possibilities variation remain.

The Heisenberg uncertainty principle and invariance of the separation between space-time events are axioms that the logical formalism of the theory must embed.

The term operator usually comes into the discussion from the formalism of linear vector spaces. Operators modify vectors and each other to form algebras which must conform to the principles of the theory.

Chipper Q
Chipper Q
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Thanks, Mark, this is quite

Thanks, Mark, this is quite helpful. Is there a place in the Standard Model for Planck-sized BHs? How does a neutrino compare to what a Planck-sized BH would be like? If an electron and proton can be made to share the same space-time, they form a neutron, and neutrons can collapse even further, right? I'm trying to imagine if there could be a minimum concentration of Planck-sized BHs, within the DM halo, that would form a lattice (due to equilibrium with the high concentration of regular matter/energy). I found a remarkable illustration of how fermions can “take the character of a boson” in a superconducting lattice: Cooper Pairs

-edit- The above link seems to pull up the HyperPhysics main page, so please click on "Index" and then "Cooper Pairs" to see the illustration I mention.

klasm
klasm
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ChipperQ: A few things.

ChipperQ:

A few things. First a small black hole is not a stable object, they radiate energy an evaporate. Due to a quantum mechanical effect a black hole is not entirely black, they radiate energy at a rate which depens on their mass. The lower the mass the faster they loose energy this way, they become "hotter". When a black hole is small they losoe energy fster this way than they can absorb it, and they evaporate completely in a small explosion, or flash.
In fact there is a chance that this kind of small black holes can be produced in the LHC when it comes online.

A neutron is different from a small black hole in among other things the way it interacts with the weak nuclear force. Thatis the force which among other things is responsible for certain kinds of radioacticve decay of atomic nuclei.

Neutrons can't really collapse further on their own. But inside things like neutron stars many neutron can begin to merge with each other.

The uncertainty principle is, despite how it is often presented in physics textbooks, not a principle that you need to assume or put into the theory on its own. This "principle" is a mathematical consequence of other parts of quantum mechanics and is there already in the mathematical theory for fourier analysis.

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