[HN Gopher] We Need to Study Nothing
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We Need to Study Nothing
Author : dnetesn
Score : 41 points
Date : 2022-08-04 11:44 UTC (11 hours ago)
(HTM) web link (nautil.us)
(TXT) w3m dump (nautil.us)
| kmerroll wrote:
| Came here looking for this:
| https://www.youtube.com/watch?v=8An2SxNFvmU
|
| Left disappointed.
| Agamus wrote:
| Do any experts know if there is any overlap in this research with
| the study of quantum fluctuations in empty space?
|
| https://youtu.be/zNVQfWC_evg?t=1260 (David Tong: Quantum Field
| Theory)
| golemotron wrote:
| This might be the most Nautilus article ever.
| mandis wrote:
| If the universe is expanding outwards, are these voids also
| moving similarly? I just cant ever seem to reconcile the
| expansion theory with the theory of galaxies/voids merging or
| colliding.
| inversalAutoDoc wrote:
| Does a void move?
|
| No really, by our current definition of 'void', does a void
| move or is its position and shape solely defined by the objects
| moving into and around it? Separately, is the void inside the
| universe the same as the void outside the universe, or is it
| fundamentally different somehow?
|
| I don't expect we'll ever answer the second question, but the
| first is able to be answered by how we choose to define the
| term 'void'.
| jmholla wrote:
| That sounds almost like the same thing as asking do holes
| move, or do electrons move? Yes, to both. The movement of one
| is made apparent by the other.
|
| Of course, I'm almost certainly wrong on both accounts.
| ziddoap wrote:
| Voids are a description of an area that has relatively less
| matter density than the average of the universe, not objects
| themselves, so I'm not sure what you mean by a void "moving".
|
| > _Separately, is the void inside the universe the same as
| the void outside the universe, or is it fundamentally
| different somehow?_
|
| By definition they are different. Voids, as I said, are areas
| within the universe that have relatively less matter density.
| Key thing being that they are part of the universe, whereas
| 'outside the universe' is, well, not part of this universe.
| JadeNB wrote:
| > Voids are a description of an area that has relatively
| less matter density than the average of the universe, not
| objects themselves, so I'm not sure what you mean by a void
| "moving".
|
| I think that was exactly the point that your parent
| https://news.ycombinator.com/item?id=32342806 was making:
|
| > Does a void move? No really, by our current definition of
| 'void', does a void move or is its position and shape
| solely defined by the objects moving into and around it?
|
| That is, I think that they were not asking a factual
| question--"obviously voids can move, but do they?"--but
| rather a sort of ontological question--"does it even make
| sense to ask whether voids move?"--just as you are.
| ozzydave wrote:
| Some areas of space have a more matter than others e.g.
| galactic clusters, where the relative speed of the galaxies to
| each other is higher than the expansion. This video from the
| excellent Space Time series helps explain it:
| https://youtu.be/bUHZ2k9DYHY
| PaulDavisThe1st wrote:
| From TFA:
|
| > The motions of individual galaxies are hundreds of times
| larger than the effect of cosmological expansion
| svachalek wrote:
| From the perspective of any galaxy, most other galaxies are
| moving away from it, "outward". But some galaxies are close
| enough to form clusters that are gravitationally bound, which
| can cause them to orbit each other or merge.
|
| We can say the visible universe is expanding outwards, because
| we see light from more and more distant things as the universe
| ages. But the actual (not just visible) universe may be
| infinitely large, we don't know what's beyond the range we can
| see (limited by the speed of light, unless we discover
| something radically new about physics we can never see
| farther). So if you look at the universe from a holistic point
| of view, not just from our perspective which makes us the
| center of the universe, expansion may not really be the best
| way to think about it. It's more like the size of the empty
| parts is increasing relative to the size of the not-empty
| parts.
| swid wrote:
| We don't necessarily see more light as the universe ages, nor
| do we see farther away. The universe is expanding, and the
| farther something is, the faster it is moving away from us.
| It can even be moving faster than the speed of light relative
| to us, because the space between us is growing, and more
| empty space between us, the more this extra stacks up. When
| this happens, something is beyond the visible universe - that
| light can never reach us.
|
| So there are two ways we cannot see something - if the
| universe is not old enough for light to reach us yet, or if
| there is too much new universe being created in between us
| and the light for the light to catch up to us.
|
| In a far enough future, there will be no other galaxies in
| the sky as all the matter will be too far away for light to
| reach us.
| [deleted]
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