[HN Gopher] Study suggests a 'dark mirror' universe within ours ...
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       Study suggests a 'dark mirror' universe within ours where atoms
       failed to form
        
       Author : clockworksoul
       Score  : 50 points
       Date   : 2024-02-20 19:48 UTC (3 hours ago)
        
 (HTM) web link (www.livescience.com)
 (TXT) w3m dump (www.livescience.com)
        
       | tiagod wrote:
       | The paper: https://arxiv.org/abs/2401.12286
        
       | dang wrote:
       | Url changed from https://futurism.com/the-byte/dark-matter-
       | mirror-universe, which points to this.
        
       | SoftTalker wrote:
       | "Dark matter is the mysterious, unknown substance that seems to
       | make up the bulk of all the mass in the universe; for every 2
       | pounds (1 kilogram) of regular matter, there's roughly 10 pounds
       | (5 kg) of dark matter."
       | 
       | ...
       | 
       | "This symmetry would help explain why dark matter and regular
       | matter have roughly the same abundances."
       | 
       | So 1 is "roughly the same" as 5, or is this an orders-of-
       | magnitude comparison?
        
         | yokaze wrote:
         | "Roughly the same abundances" meaning, why we usually (but not
         | always) find evidence of dark matter in places, where we see
         | regular matter.
        
         | delecti wrote:
         | It seems that yes, they're saying that 1 and 5 are roughly the
         | same. Basically, why is the matter in the universe ~20% "non-
         | dark", and not 1%, or .001%?
        
           | timeagain wrote:
           | There's that old joke that computer scientists think any
           | numbers within a power of two are equal, physicists think any
           | numbers within a power of 10 are equal, and mathematicians
           | only distinguish between finite numbers and infinity.
           | 
           | Edit: and engineers are as precise as they are paid to be.
        
           | xjay wrote:
           | "The 80/20 rule"/The Pareto principle
           | 
           | > Mathematically, the 80/20 rule is roughly described by a
           | power law distribution (also known as a Pareto distribution)
           | for a particular set of parameters. Many natural phenomena
           | distribute according to power law statistics. It is an adage
           | of business management that "80% of sales come from 20% of
           | clients." [1][2]
           | 
           | [1] https://en.wikipedia.org/wiki/Pareto_principle
           | 
           | [2] https://en.wikipedia.org/wiki/Power_law
        
         | labster wrote:
         | In astronomy and cosmology, 1 and 5 are the same number. Only
         | the orders of magnitude matter when talking about large things.
         | At atomic scales and in photon length the precise numbers do
         | matter.
        
           | PaulHoule wrote:
           | ... if dark matter is something totally different from light
           | matter there might be 1000x more of it.
        
             | neltnerb wrote:
             | They're describing relative mass, which is related to
             | gravitational attraction and inertia, whether there is
             | "more" is not something they measured.
             | 
             | What is "more"?
        
               | PaulHoule wrote:
               | Total mass as measured by gravitation effect.
        
         | BurningFrog wrote:
         | Also in astronomy, all elements other than hydrogen and helium
         | are considered "metals":
         | https://public.nrao.edu/blogs/astronomy-is-metal/
         | 
         | It's really not an exact science...
        
           | shrimp_emoji wrote:
           | Well, at astronomical scales, everything's mostly just
           | hydrogen with tiny bits of hard stuff mixed in. :p
        
           | ClassyJacket wrote:
           | >It's really not an exact science...
           | 
           | I think this is the first time I've ever heard someone use
           | this phrase in reference to an actual science
        
       | woah wrote:
       | Waiting for the sci fi movie
        
       | tanvach wrote:
       | Curious about conservation of charge - if all dark protons were
       | to decay then there must be also an abundance of dark positrons?
        
         | ars wrote:
         | You misread the article, it was not saying there are dark
         | protons. It was using proton decay as an analogy.
         | 
         | But to answer your question anyway, if a proton did decay then
         | yes, it would be to a positron plus something else.
        
       | shrimp_emoji wrote:
       | So that's where we go when we die?
        
         | bemusedthrow75 wrote:
         | And now it's a sci-fi _horror_ movie.
        
       | amriksohata wrote:
       | Unrelated, but somewhat interesting in Hindu cosmology and
       | ancient scriptures the edges of the bubble of the universe store
       | everything happening, that has happened and is to happen.
        
         | bookofjoe wrote:
         | "The past, present and future are only illusions, even if
         | stubborn ones." -- Albert Einstein in a letter to a friend
        
         | CyanBird wrote:
         | Same in actual cosmology, it is called the holographic
         | principle. The concept is that 3D bodies can be losslessly
         | represented on a distant 2D plane which envelops them or
         | alongside the spherical perimeter of a black hole if they are
         | squished to it
         | 
         | It is not all that applicable, but it is interesting to think
         | about and there are people studying it
        
       | ChrisClark wrote:
       | I have joked before about the apparent lack of life in the
       | universe, that we are just living in unencrypted 'plain text'
       | mode. But all the developed aliens have moved to encrypted space.
       | ;)
        
         | disadvantage wrote:
         | Humans have went dark considerably over the years. I don't know
         | the exact date when encrypted comms became the norm, but we
         | rarely transmit plaintext out into the Universe anymore. We
         | still leak plaintext, but the vast majority is encrypted now.
        
         | zer00eyz wrote:
         | Maybe were stuck here cause were made out of meat...
         | 
         | https://www.mit.edu/people/dpolicar/writing/prose/text/think...
         | 
         | https://www.youtube.com/watch?v=T6JFTmQCFHg
        
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