5 ms·

Our very own Milky way is inside the KBC void [0] discussed in the article. It never ceases to amaze me that our local group [1], part of the local Laniakea sup

Our very own Milky way is inside the KBC void [0] discussed in the article. It never ceases to amaze me that our local group [1], part of the local Laniakea supercluster [2], despite the hundred of thousand of galaxies it contains is almost empty space and part of the void! [0] https://en.wikipedia.org/wiki/KBC_Void https://en.wikipedia.org/wiki/KBC_Void [1] https://en.wikipedia.org/wiki/Local_Group https://en.wikipedia.org/wiki/Local_Group [2] https://en.wikipedia.org/wiki/Laniakea_Supercluster https://en.wikipedia.org/wiki/Laniakea_Supercluster

seibelj 6y ago
Could this be why we exist? Aliens don't like to travel across space desert, it isn't worth their time and risk, so we are in an island of safety.
- NKosmatos 6y ago
  Nice one!!! Never thought of it that way. On the other hand I now feel more isolated, knowing our civilization is just a flower in the desert that most probably no one is going to notice.
- wffurr 6y ago
  Grimdark fiction[0] aside, I doubt anything is traveling across intergalactic voids of any size. [0]: https://warhammer40k.fandom.com/wiki/Tyranids https://warhammer40k.fandom.com/wiki/Tyranids
  - koheripbal 6y ago
    I saw an MIT PhD thesis defense video of a paper that described the calculations of how far/fast probes could spread between galaxies. I really wish I could find it again... but my searches have failed. The conclusion was that self-replicating probes could indeed populate (I forget how many - on the order of hundreds of thousands/millions) nearby galaxies within the last couple billion years. It was pretty compelling. The discussion at the end did see some debate of "well then where are they?". A valid question. Why haven't self-replicating probes infected the entire visible universe by now?
    - mellosouls 6y ago
      This is essentially the question raised by the Fermi Paradox. https://www.wikipedia.org/wiki/Fermi_paradox https://www.wikipedia.org/wiki/Fermi_paradox
    - trhway 6y ago
      wouldn't it be like we did with plastic bottles to the oceans? only imagine if the bottles could self-replicate. Pollution at intergalactic scale. Probably getting to specific levels of technology requires specific level of consciousness - a corresponding level of awareness about actions and consequences. A technological level increase without corresponding consciousness level increase is probably one of the great filters. Like for example human civilization failure to recognize the human civilization induced global warming. wrt. original post : >For ΛCDM to fit the pattern of fluctuations observed in the CMB by the Planck satellite and other experiments, the Hubble constant must have a particular value of 67.4 ± 0.5 km/s/Mpc. Local measurements are nearly all above this ‘Planck value’, but are consistent with each other. In our paper, we use a local value of 73.8 ± 1.1 km/s/Mpc using a combination of supernovae and gravitationally lensed quasars, two particularly precise yet independent techniques. I think it is not an accident that c divided by the age of the universe (meaning that those stars have been flying away from us with constant speed c) produces 71km/s/Mpc. That also means that there is no acceleration nor deceleration - stars fly away from us with constant speed [Hubble constant x distance] with the distance growing and the Hubble constant decreasing resulting in the same speed for any given star.
    - sliken 6y ago
      Sounds pretty close to http://www.fhi.ox.ac.uk/wp-content/uploads/intergalactic-spreading.pdf http://www.fhi.ox.ac.uk/wp-content/uploads/intergalactic-spr... Who is to say there isn't such a probe in the solar system currently? Said probe could be watching earth for promising or dangerous signs and deciding what to do.
      - koheripbal 6y ago
        Because of your comment, I was able to find it... https://www.youtube.com/watch?v=zQTfuI-9jIo https://www.youtube.com/watch?v=zQTfuI-9jIo Seems it was Oxford, not MIT.
- colechristensen 6y ago
  Considering the hundred billion stars in our galaxy, it’s hard to imagine if there were threatening alien life anywhere in the universe that it wouldn’t be in our own galaxy.
- gfodor 6y ago
  At this scale this seems an unlikely explanation, given that we are in an oasis of the 'desert' containing hundreds of thousands of galaxies.

seibelj 6y ago

Could this be why we exist? Aliens don't like to travel across space desert, it isn't worth their time and risk, so we are in an island of safety.

NKosmatos 6y ago
Nice one!!! Never thought of it that way. On the other hand I now feel more isolated, knowing our civilization is just a flower in the desert that most probably no one is going to notice.
wffurr 6y ago
Grimdark fiction[0] aside, I doubt anything is traveling across intergalactic voids of any size. [0]: https://warhammer40k.fandom.com/wiki/Tyranids https://warhammer40k.fandom.com/wiki/Tyranids
- koheripbal 6y ago
  I saw an MIT PhD thesis defense video of a paper that described the calculations of how far/fast probes could spread between galaxies. I really wish I could find it again... but my searches have failed. The conclusion was that self-replicating probes could indeed populate (I forget how many - on the order of hundreds of thousands/millions) nearby galaxies within the last couple billion years. It was pretty compelling. The discussion at the end did see some debate of "well then where are they?". A valid question. Why haven't self-replicating probes infected the entire visible universe by now?
  - mellosouls 6y ago
    This is essentially the question raised by the Fermi Paradox. https://www.wikipedia.org/wiki/Fermi_paradox https://www.wikipedia.org/wiki/Fermi_paradox
  - trhway 6y ago
    wouldn't it be like we did with plastic bottles to the oceans? only imagine if the bottles could self-replicate. Pollution at intergalactic scale. Probably getting to specific levels of technology requires specific level of consciousness - a corresponding level of awareness about actions and consequences. A technological level increase without corresponding consciousness level increase is probably one of the great filters. Like for example human civilization failure to recognize the human civilization induced global warming. wrt. original post : >For ΛCDM to fit the pattern of fluctuations observed in the CMB by the Planck satellite and other experiments, the Hubble constant must have a particular value of 67.4 ± 0.5 km/s/Mpc. Local measurements are nearly all above this ‘Planck value’, but are consistent with each other. In our paper, we use a local value of 73.8 ± 1.1 km/s/Mpc using a combination of supernovae and gravitationally lensed quasars, two particularly precise yet independent techniques. I think it is not an accident that c divided by the age of the universe (meaning that those stars have been flying away from us with constant speed c) produces 71km/s/Mpc. That also means that there is no acceleration nor deceleration - stars fly away from us with constant speed [Hubble constant x distance] with the distance growing and the Hubble constant decreasing resulting in the same speed for any given star.
  - sliken 6y ago
    Sounds pretty close to http://www.fhi.ox.ac.uk/wp-content/uploads/intergalactic-spreading.pdf http://www.fhi.ox.ac.uk/wp-content/uploads/intergalactic-spr... Who is to say there isn't such a probe in the solar system currently? Said probe could be watching earth for promising or dangerous signs and deciding what to do.
    - koheripbal 6y ago
      Because of your comment, I was able to find it... https://www.youtube.com/watch?v=zQTfuI-9jIo https://www.youtube.com/watch?v=zQTfuI-9jIo Seems it was Oxford, not MIT.
colechristensen 6y ago
Considering the hundred billion stars in our galaxy, it’s hard to imagine if there were threatening alien life anywhere in the universe that it wouldn’t be in our own galaxy.
gfodor 6y ago
At this scale this seems an unlikely explanation, given that we are in an oasis of the 'desert' containing hundreds of thousands of galaxies.