[HN Gopher] Ultracold, superdense atoms become invisible
___________________________________________________________________
Ultracold, superdense atoms become invisible
Author : gmays
Score : 73 points
Date : 2021-11-19 18:49 UTC (4 hours ago)
(HTM) web link (news.mit.edu)
(TXT) w3m dump (news.mit.edu)
| peter_d_sherman wrote:
| If this is true, then consider the following:
|
| If we know that:
|
| A) Superconductors can conduct a theoertical infinite amount of
| electricity when supercooled (super-cooling being the key to this
| phenomena)...
|
| B) That there is a corollary; a relationship between electricity
| and information; that is, that electricity can carry information
| (unless you're reading this in the far future, the computer you
| are reading this on is proof of that! <g>), and a theoretical
| infinite amount of electricity can carry a theoretical infinite
| amount of information...
|
| C) If A and B are true, then that would imply that super-cooling
| -- is the key to being able to transfer a theoretically infinite
| amount of information, that is, there's a link, a relationship
| between super-cold things (super low temperatures) -- and the
| ability to pass information through it...
|
| So, that brings us to the title of this article: "Ultracold,
| superdense atoms become invisible".
|
| If this article is true, then not only is there a link between
| super-cold temperatures, the ability to pass theoretically
| infinite information through a superconducting material (which
| really just consists of atoms of the superconducting substance,
| which really just consists of probable repeating structure of
| that substance's atoms in space...) but also atom invisibility...
|
| So, if true, we have ultra-cold, invisibility, and theoretical
| infinite information... all at the same place, at the same
| time...
|
| OK, so with that background, I'm going to go for "full crackpot"
| here... <g>
|
| If atoms (or heck, any subparticle really, this would include any
| and every subparticle) -- become invisible when super-cooled --
| then:
|
| Question #1: Are they really there, at all? (When super-cooled?)
|
| Question #2: If the answer to Question #1 is that they are not
| (again, when super-cooled), that they somehow collapse (for the
| time that they are super-cooled) and then re-emerge when heated
| (boy, wouldn't this solve all problems of all kinds of atoms and
| sub-particles "disappearing" and "reappearing" if true?) -- then
| here's "full crackpot":
|
| If all of that were true -- then couldn't any single atom or sub-
| particle (any of them, no matter how small) -- be modeled and/or
| viewed as _INERTIA_ -- but _INERTIA RELATIVE TO SCALE_ , _INERTIA
| RELATIVE TO TEMPERATURE_... or more specifically _INERTIAL FIELDS
| RELATIVE TO TEMPERATURE_ , or even more specifically _INERTIAL
| FIELDS RELATIVE TO TEMPERATURE, RELATIVE TO SCALE_...
|
| Well, if one or more things, one or more aspects of the above
| logic is false, then the answer is 'No'...
|
| But who knows?
|
| Maybe it's possible...
|
| And then again, maybe it isn't... <g>
|
| In other words, if true -- all atoms, particles and subparticles,
| all of them -- are INERTIA (force) -- at their relative scale...
| byteware wrote:
| A) there is a critical current density above which
| superconductivity collapses, so no infinite current, not even
| theoretically
| gus_massa wrote:
| They are only invisible for a laser with a color with low
| energy that can only "move" the atoms. When light colides with
| an atom and changes direction, the atom has some speed after
| the colission.
|
| If the atoms can't move because there are other atoms blocking
| them, then the can't redirect the light. [I oversimplified a
| few details here.]
|
| If you use a laser with other color, then the light can be
| absorbed by the electrons in the atoms, and the electrons can
| jump and later emit the light. So it will not be visible with
| another laser. [Probably an ultraviolet laser is enough.]
|
| > _Question #1: Are they really there, at all? (When super-
| cooled?)_
|
| Yes.
| trhway wrote:
| >"An atom can only scatter a photon if it can absorb the force of
| its kick, by moving to another chair," explains Ketterle,
| invoking the arena seating analogy. "If all other chairs are
| occupied, it no longer has the ability to absorb the kick and
| scatter the photon. So, the atoms become transparent."
|
| by that logic neutron stars should be highly
| transparent/invisible too.
| NickNameNick wrote:
| Maybe? But wouldn't you expect at least some non-degenerate
| matter on the surface of a neutron star?
|
| I doubt we'll find any 'naked' neutron stars.
| philipkglass wrote:
| There is something missing from this press release.
|
| _In their new study, he and his colleagues used techniques they
| developed previously to first freeze a cloud of fermions -- in
| this case, a special isotope of lithium atom, which has three
| electrons, three protons, and three neutrons. They froze a cloud
| of lithium atoms down to 20 microkelvins, which is about 1
| /100,000 the temperature of interstellar space._
|
| _"We then used a tightly focused laser to squeeze the ultracold
| atoms to record densities, which reached about a quadrillion
| atoms per cubic centimeter," Lu explains._
|
| They're freezing lithium 6 vapor and increasing its density. But
| lithium 6 is normally a solid at room temperature. Solid lithium
| 6 would contain about
|
| (6.02 * 10^23 / 6.0151 [0]) * 0.460 [1] = 4.6 * 10^22
|
| atoms per cubic centimeter -- a density 7 orders of magnitude
| greater than what has been attained in this work. Is there
| something special that prevents this frozen atom cloud from
| condensing to an ordinary solid? Is it just a very short lived
| state observed before it condenses to an ordinary solid?
|
| [0] Atomic weight of lithium 6
|
| [1] Specific gravity of lithium 6:
| https://aip.scitation.org/doi/abs/10.1063/1.1743927
| Misdicorl wrote:
| The missing piece is that the coldness of the atoms isn't a
| random stat. It's an incredibly important feature of this
| research field. The density in the context of a quantum gas is
| what's interesting
| liquidise wrote:
| In general their article's use of "Fermion" clashes with my
| understanding. I've understood fermions[1] to be a type of sub-
| atomic particle, like an electron. The article routines refers
| to them as if they are atoms themselves, including your quoted
| test.
|
| I presume the MIT literature knows more than i do here, but i'm
| unsure what i am missing. Anyone have an idea?
|
| 1. https://en.wikipedia.org/wiki/Fermion
| contravariant wrote:
| The term "fermion" is often used for everything with a half-
| integer spin. This is because their wave-functions are still
| anti-symmetric and therefore the Pauli exclusion principle
| applies leading to Fermi-Dirac statistics.
|
| A lot of terms are reused for what are technically compound
| particles, especially since it isn't always too obvious which
| properties of a particle are intrinsic and which are caused
| by interactions.
| dragonwriter wrote:
| Read the "Composite Fermions" part of the Wikipedia article
| you posted. Anything, including many atoms, composed of an
| odd number of fermions is, itself, a fermion (and anything
| composed of an even number of fermions is a boson.)
| TheCraiggers wrote:
| If I understand this correctly, couldn't this explain dark
| matter?
|
| The article didn't say how dense this cloud was, but if it was
| still a cloud it couldn't be _that_ dense right? Surely something
| that could exist in the cold vastness of space.
| gpm wrote:
| Near absolute zero states of matter don't really work the same
| way. I wouldn't read too much into them saying "cloud".
| ben_w wrote:
| The cosmic microwave background is 136000 times hotter, so I
| don't think so, no.
| dtgriscom wrote:
| "136000 times hotter" sounds a lot more impressive than
| "2.72546 degrees hotter"...
| BobbyJo wrote:
| That was fun to read. Even funner to realize that the huge
| relative number is actually more useful too. Saying 2.72
| degrees sounds small, but a difference that large on
| average throughout the universe would be absolutely insane
| And break basically all of physics
| TheCraiggers wrote:
| Fair, but the article implied that it's a somewhat linear
| effect- you don't need absolute zero for it to make the cloud
| dim. The article didn't do a great job of saying what temps
| they were testing at.
|
| Still, I'm not surprised. I doubt some armchair scientist is
| going to solve the riddle of dark matter. I was curious and
| got some good answers. Thanks!
| jwuphysics wrote:
| No. The experimentalists used lasers to condense the atoms to
| high densities.
| klyrs wrote:
| Sounds like a fun conspiracy. Aliens using space lasers to
| hide, what, 25% of the matter in the universe from us?
| ben_w wrote:
| 85%, not that it would matter for a conspiracy theory.
| GuardianCaveman wrote:
| Yeah the 25% coolest parts too.
| denton-scratch wrote:
| Would that be the 25% that isn't "Dark Matter"? Ergo,
| nothing in the Universe is observable ... wait.
| fcsonline wrote:
| Dark matter?
| gmuslera wrote:
| Didn't understand if it stops but do not bounce back light or if
| it lets light to pass as there was nothing there. Those are
| different ways to be invisible.
| Shadonototra wrote:
| .. to our current technology
|
| That's the missing point, invisible is subjective
| gus_massa wrote:
| It's invisible only for the light of colors with photons with
| low energy, because the trick only blocks some interactions of
| the material and light.
|
| If you use light with photons with more energy [perhaps
| ultraviolet] then other interactions are possible and it is
| visible.
|
| So "invisible" is a simplification/exaggeration in the press
| article.
| ergocoder wrote:
| Physics is a highly speculative field due the limitation of our
| technology.
|
| Physicists know this. But laypeople don't.
|
| With the anti and pro science folks, this part is getting worse
| where you are called multiple insults for even casting doubt on
| any physics theory/law like "nothing can be faster than speed
| of light" or "energy is always conserved".
| [deleted]
___________________________________________________________________
(page generated 2021-11-19 23:00 UTC)