[HN Gopher] Astronomers discover complex carbon molecules in int...
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Astronomers discover complex carbon molecules in interstellar space
Author : Brajeshwar
Score : 124 points
Date : 2024-10-25 15:46 UTC (1 days ago)
(HTM) web link (www.sciencealert.com)
(TXT) w3m dump (www.sciencealert.com)
| JanisErdmanis wrote:
| > This discovery also links to another important finding of the
| last decade - the first chiral molecule in the interstellar
| medium, propylene oxide. We need chiral molecules to make the
| evolution of simple lifeforms work on the surface of the early
| Earth.
|
| It would be really amazing if we were able to know if both
| chiralities are equally represented in the space. Apart from the
| life itself it is astonishingly interesting how life evolved to
| be monochiral.
| echelon wrote:
| Samples from space of an iso-energetic chiral molecule are
| going to show a racemic mix. Unless there's a discrete reaction
| path favoring handedness.
| westurner wrote:
| Does propylene oxide demonstrate a "propeller effect" like some
| other handed chiral molecules?
|
| From https://news.ycombinator.com/item?id=41873531 :
|
| > _" Chiral Colloidal Molecules And Observation of The
| Propeller Effect"
| https://pmc.ncbi.nlm.nih.gov/articles/PMC3856768/_
| m463 wrote:
| I wonder something similar on a larger scale...
|
| I wonder if planets revolve around stars cw vs ccw evenly
| distributed.
|
| (and could these kinds of things be related?)
| deathanatos wrote:
| > _I wonder if planets revolve around stars cw vs ccw evenly
| distributed._
|
| Depends on whether you view it from one side or the other,
| no? Or, how do you define which side of a planetary system is
| the "top"?
| Brian_K_White wrote:
| Doesn't matter. The names for the directions are arbitrary
| and you can pick whatever frame of reference you like. The
| question was only if the directions are distributed
| randomly.
| m463 wrote:
| hmmm, maybe not as analogous to chirality as I thought?
| pushupentry1219 wrote:
| To put the questions differently: assume we look at all the
| planets from the perspective of a single point (say,
| Earth), why do some spin one way (cw) and some spin the
| other way (ccw)? Are cc and ccw evenly distributed?
| seanhunter wrote:
| They seem to spin in different directions because you are
| observing them from a single point - earth.
|
| Consider the following. You and I are standing on
| opposite sides of a pane of glass. I spin a wheel
| parallel to the pane of glass and we both observe it.
| From my side of the glass the wheel is spinning
| clockwise. From your point of view (because you are
| seeing the opposite side of the wheel) it is spinning
| counterclockwise.
|
| Whether a given rotation is clockwise or counterclockwise
| depends entirely on your reference frame - they really
| don't have a robust definition that doesn't depend on the
| pov of the observer.
|
| There is a really excellent and clear description of the
| problem and solution to this that is employed in
| classical mechanics here[1] but if you only care about
| the solution, by convention we employ the right hand
| rule. If you and I both agree a common direction in the
| plane of rotation of the wheel say parallel to the floor
| off to the side (whichever side doesn't matter but for
| one of us it will be to the left and the other right),
| point our right hand index finger in that direction
| (called r hat or the direction of radial motion) and curl
| our two smallest fingers in the direction of rotation of
| the wheel, our thumbs will be pointing parallel with one
| another. This would be called n hat (normal motion), and
| is the direction of any vectors which are the cross
| product of two vectors in the plane of rotation of the
| wheel. As a bonus if you make your right hand middle
| finger perpendicular to the index finger you have theta
| hat (tangential motion). Now even though you and I can't
| agree whether the wheel is spinning clockwise or
| counterclockwise we have three identical basis vectors
| and can use these to form a common polar coordinate
| system to describe this rotating system.
|
| [1] https://www.youtube.com/watch?v=q785KV5ZIN0&t=45s
| analog31 wrote:
| Rotation can be described as a vector, pointing along the
| axis of rotation. You could imagine writing down the
| vectors for all of the objects in a planetary system, and
| doing some kind of statistics on the numbers to see if
| there was a preference for a particular axis. You could use
| a sign convention such as the right hand rule.
|
| The rotation vector is associated with another, which is
| angular momentum. The reason why there's all kinds of
| spinny stuff in a solar system, or a galaxy, is that the
| massive objects jointly conserve the total angular momentum
| of the blob of dust that the system coalesced from.
|
| Neutrinos are another beast, they have a preference for one
| direction of their spin quantum number:
|
| https://neutrinos.fnal.gov/mysteries/handedness/
|
| In fact you could use the spin of neutrinos to say that the
| sign convention for rotation is not arbitrary.
| olddustytrail wrote:
| If you consider the North Pole to be the top of the Earth,
| then the Earth rotates counter clockwise, and so does the
| Sun, and the Earth orbits the Sun ccw also.
|
| This is true for most of the other planets also and they
| orbit in the same plane.
|
| And this is true for most stars in the galaxy and the
| rotation of the galaxy itself too.
|
| So it's pretty much all counter-clockwise.
| seanhunter wrote:
| And if you consider the South pole to be the top of the
| Earth then the Earth rotates clockwise and so does the sun
| and the eath orbits the sun clockwise also. It's pretty
| much all an arbitrary convention and depends on your frame
| of reference.
|
| If you define North to be "the pole that if it's on the top
| then things rotate counterclockwise" and that's consistent
| then that's equivalent to the definition of an orientable
| Euclidian space I think, and I'm glad that's the case for
| our universe because things would be mighty weird if it
| weren't. You could shift your breakfast around the table
| and it would come back as a mirror image of itself.
|
| Joking aside as I understand it any orientable 3-d space
| admits two orientations, which are defined by the choice of
| the surface normal n. If you do it the way I said in a
| sibling post with the right-hand rule then n is pointing
| paralel to the axis of the Earth with positive in the
| direction of the North pole, the rotation is
| counterclockwise from that perspective and everything is
| groovy. But we could equally use our left hand, our thumb
| would point South and the rotation of the Earth would be
| clockwise. In that case we are choosing to orient using the
| other possible surface normal (-n).
| olddustytrail wrote:
| If you take the South Pole as the top, then the Earth
| rotates clockwise, which is the SAME (this is the
| important bit) as the Sun, which is the SAME as the solar
| system, which is the SAME as the Galaxy. They're (nearly)
| all clockwise.
| Etherlord87 wrote:
| The Sun and most planets and in general stuff rotates in
| the same direction because it formed from a cloud that
| had some movement, caused by a bifurcation at some point
| of its formation. Bifurcation meaning losing balance in
| chaos and moving away from that initial unstable
| equilibrium into a significant motion.
|
| So it shouldn't be surprising stuff is for the most part
| moving in the same direction. It's surprising when
| something isn't, probably because it was hit by some body
| changing its angular velocity.
|
| The same goes for the alignment of equators.
| UniverseHacker wrote:
| Life has to be monochiral because biochemical reactions are
| catalyzed by physical machines- enzymes, where an entirely
| different physical shape of the enzyme active site would be
| required for it to work with the opposite isomer. Any
| particular DNA sequence that evolves to make a protein will
| only be able to work with one orientation- unless the enzyme
| was so floppy and flexible that it reacts with everything,
| which would be inherently dangerous to a living cell.
|
| Think about trying to "evolve" a glove that fits perfectly on
| both hands yet is also specific and does not accidentally fit
| onto non-hands... it would be much harder and less likely than
| evolving one that only fits left or only right hands.
|
| Spontaneous chemical reactions that make the things we find in
| space never had to physically fit into a machine like a key
| into a lock, so both chiral isomers are equally likely to form.
| kunley wrote:
| Just saying that on the same webpage there was a link to an
| article about the guy with three p*nises...
| SoftTalker wrote:
| uBlock is your friend unless you're in to that sort of thing.
| Not that there's anything _wrong_ with it...
| saurik wrote:
| Does uBlock leave some kind of explanation in the place of
| the ad telling you what overall quality of ad it was? Like,
| the message you are responding to isn't complaining about
| having to see the link: they are noting that this kind of
| cross-promotion might lead one to discredit the content we
| are reading, as it is kind of an important signal, not merely
| noise.
| notahacker wrote:
| Hate to disappoint anyone searching, but it turns out two of
| them were vestigial and fully enclosed, to the point the
| deceased individual probably never realized it. Although if he
| did, giving his body to medical science was a great way to let
| everybody else know...
| kunley wrote:
| I was rather under impression that this whole news source was
| just spreading things catchy but made up, including said
| carbomolecule..
| anigbrowl wrote:
| This is a shitty news source, please use a better one
| gus_massa wrote:
| Do you have any recomendation? Sometimes the same press release
| is posted by different news blogs. If there is a better one or
| the original one, dang may decide to change it.
| olddustytrail wrote:
| MIT News perhaps https://news.mit.edu/2024/scientists-
| discover-molecules-stor...
| Brajeshwar wrote:
| I'm beginning to think that I might remove them from my source.
| Almost all of their articles are reprints of the reprints of
| originals from elsewhere. I haven't checked and cleaned my
| sources in more than a year. I will do a retrospection during
| the yearly cleanup in December.
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