[HN Gopher] Gravity: We might have been getting it wrong
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Gravity: We might have been getting it wrong
Author : ryan_j_naughton
Score : 55 points
Date : 2020-01-24 19:00 UTC (4 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| xhkkffbf wrote:
| If we can't figure out gravity, what hope have we of doing ANY
| science? I mean stuff falls. Everything falls. The orbits of the
| planets aren't that complex, but gravity pretty much predicts
| them close to perfectly.
| jdkee wrote:
| "Science is magic that works."
|
| -K. Vonnegut
| dwaltrip wrote:
| We have a working model of gravity that is very accurate in an
| incredibly broad array of circumstances. You acknowledge this
| in your comment.
|
| This is a scientific result. What are you trying to say?
| xenocyon wrote:
| It's not that we can't model gravity at planetary-orbit scales;
| that's been done. The issue is that relativity (which addresses
| gravity) is a good model at large scales and the quantum
| "Standard Model" (which addresses the other three forces) is a
| good model at small scales, but these two models are
| incompatible with each other and no falsifiable theory that
| works at all scales has yet been found.
| gumby wrote:
| this pop sci article does address that: we have a good theory
| of gravity at macroscopic scale but none at the quantum level.
| hannob wrote:
| I don't understand a lot about how the computer in front of me
| works (ok, I know more than the average person, but still I
| don't know a whole lot). Yet I'm still able to use it.
|
| We understand enough of the effects gravity to describe most
| phenomena that are relevant for most other parts of science.
| From my lay understanding what physicists are missing is how to
| tie in gravity with all the other theories they believe are
| true. However the effects, whatever they are, are so small that
| we can in most cases just ignore them.
| empath75 wrote:
| How does gravity impact photons and quarks? That's the part
| that's missing.
| tiborsaas wrote:
| Even the title is wrong, we know for a fact that we are getting
| gravity wrong.
|
| A better article with actual content:
|
| https://www.ipmu.jp/en/20190619-symmetry
| pdonis wrote:
| _> we know for a fact that we are getting gravity wrong_
|
| This statement is way, way too strong. We have a theory of
| gravity, General Relativity, which has had its predictions
| confirmed by countless experiments, in some cases to thirteen
| or fourteen decimal places. That is not "getting it wrong".
|
| Many physicists believe that GR, as well confirmed as it is,
| can't be the final fundamental theory of gravity because it's
| not a quantum theory. But nobody has yet found a quantum theory
| of gravity that (a) is consistent with the rest of quantum
| mechanics, and (b) makes experimental predictions that have
| been confirmed. Unless and until both (a) and (b) are done, the
| claim that we are "getting it wrong", even in the restricted
| sense of not having a final fundamental theory of gravity,
| because GR isn't a quantum theory is just speculation and might
| itself be wrong. It should certainly not be stated with the
| confidence you are stating it.
| makach wrote:
| gravity sucks. thanks for the link :)
| glofish wrote:
| TLDR: [...] the holographic principle allows
| physicists to study gravitational systems by projecting them on
| a boundary [...] proved that symmetry is not
| possible in a gravitational theory if it obeys the holographic
| principle. [...] meaning that symmetry would not be
| possible in quantum gravity.
| Khaine wrote:
| PBS Space Time have done a number of episodes on the
| holographic principle[1]
|
| I strongly recommend anyone interested in physics check out
| the channel
|
| [1] https://www.youtube.com/watch?v=klpDHn8viX8
| RandomBacon wrote:
| For people on a mobile device:
|
| > TLDR:
|
| > the holographic principle allows physicists to study
| gravitational systems by projecting them on a boundary
|
| > proved that symmetry is not possible in a gravitational
| theory if it obeys the holographic principle.
|
| > meaning that symmetry would not be possible in quantum
| gravity.
| [deleted]
| austincheney wrote:
| Does this account for the subject of "dark matter", which at
| this point is absent from all evidence?
| greesil wrote:
| This part is fun: "Their result has several important
| consequences. In particular, it predicts that the protons are
| unstable against decaying into other elementary particles, and
| that magnetic monopoles exist."
| reggieband wrote:
| Interesting ... another time holography in the context of physics
| has come up. Youtube recommended the Wired series where some
| expert explains some concept at different levels and one recent
| one was on Gravity [1]. In the expert section they talk briefly
| about holography and how a two dimensional surface seems to be
| able to encode all of the information of a three dimensional
| volume. They go on to speculate how this might relate to the
| event horizon of black holes. I get a bit lost since it is
| heavily edited and they are clearly talking about things beyond
| my ken. My takeaway was that there is a possibility the
| information we thought was getting lost within blackholes is
| actually still present within the surface of the event horizon.
|
| There was also a brief mention of holography in this interview
| with String Theorist Jim Gates on Lex Fridman's Youtube channel
| [2]. I can't remember the exact context of how holography is
| related to strings but I believe he was talking about how it
| could impact some of the maths behind the multiple dimensions
| some string theories required.
|
| [1] https://www.youtube.com/watch?v=QcUey-DVYjk
|
| [2] https://www.youtube.com/watch?v=vGQ3q4dO_9s
| mindcrime wrote:
| Huh, interesting. We know there are (or were) some fundamental
| asymmetries in the universe, leading to, for example, the
| imbalance in matter vs anti-matter. I wonder if this research
| will lead to anything in terms of understanding why these kinds
| of asymmetries exist?
| Ididntdothis wrote:
| An interesting question is also why the universe has any kind
| of structure and is not uniform.
| sebow wrote:
| Maybe when the scientific community will abandon the arrogance
| and piggy-backing mentality upon theories are built and upon
| which ideas are accepted into testing, we will actually get more
| results as a species.
|
| Then again, history has shown that real work is done by the
| outliers, people who think outside of the norm of stupid masses.
| wrycoder wrote:
| Much more information from a previous phys.org:
|
| https://phys.org/news/2019-05-constraints-symmetries-hologra...
|
| Their work assumes the AdS/CFT correspondence.
|
| "Our new paper provides a rigorous proof of this claim in the
| context of the AdS/CFT correspondence, where quantum gravity is
| defined in a mathematically precise way, and we have done so in
| the most general way, excluding all possible global symmetries
| from quantum gravity,"
| tus88 wrote:
| Huh. We said the same thing a bit over a century ago.
| scrumper wrote:
| Agh, mildly infuriating (enfrustrating?) article. A little tease
| about the result and then several paragraphs about how science is
| serendipitous and face to face interactions are better than email
| and video conferencing.
| pdonis wrote:
| _> mildly infuriating (enfrustrating?) article_
|
| Par for the course for phys.org.
| paulpauper wrote:
| this article is way to vague. Do they means symmetry as it
| relates to string theory or some other theory for quantum
| gravity? I was hoping for more info.
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