Does this mean we could look at deep space for clues about the physical rules that govern what happens beyond a black hole's event horizon?
Is our universe trapped inside a black hole? This JWS Telescope discovery
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Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#42Earlier quoted context omitted.
Read section 5.2 of the paper
Do you or other HN commenters understand it in a satisfying way? The author writes about the Doppler effect creating a systemic bias in brightness depending on which way the galaxies are rotating. I don't understand that argument either, but it's moot, because they state categorically that that effect would be too small to explain their results. ( "This explanation is challenged by the fact that the effect of the rot…
It's a moot point, but I *really* don't understand the Doppler-shift bias mechanism either. Help?
This one of the author's other papers they cited in this one,
https://www.mdpi.com/2073-8994/15/6/1190
I'm completely lost how they're eliding between the rotation orientation of the Milky Way galaxy, and relative linear velocities with stars in other galaxies. In the special relativity argument, where does the rotation axis of the Milky Way enter?
Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#43Earlier quoted context omitted.
There is no absolute direction for a galaxy’s spin—it’s always relative to the observer’s perspective. So I’d suspect they’re saying time and distance would need to be factored in rather than just looking at static images relative to our position today since our own spin may have caused a particular galaxy to appear to have been spinning in a different direction at another point in space-time
I don't understand this logic. To me, that's equivalent to saying "there's no absolute direction for which way a wheel spins, it's relative to the speed of the observer". Which makes no sense to me, because my definition of spin is measured against the axis of rotation of the object itself. I don't see how time-intermittent frame captures from our own position affect that interpretation. Or are we using an astonomy-s…
It’s the same as saying you can only work out how fast something is moving in relation to something else. Your car is doing 50mph on the highway, but the earth is spinning round the sun and the sun is moving around the centre of the galaxy and the galaxy is moving compared to other galaxies and so on.
Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#44Ok but then the theory of black holes are wrong because this isn’t dense at all.
Black holes need not be dense. The black hole at the centre of galaxy M87 has the density of air in our atmosphere. The larger the black hole, the less dense it is. So that alone doesn't preclude us existing inside of one.
That’s news to me, I was taught that the mass collapses into it self it creates more gravity and more matter gets sucked in because the mass is so dense. So at which point does it become less dense?
Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#45Earlier quoted context omitted.
> How does this work with matter falling into 'our' black hole and hawkins-radiation leaving our black hole? We would see that at the edge (if we could see it) there's new mass and energy, but that would be obscured by what appears as the CMB for us. > Heck, Hawkins radiation means black holes can evaporate. Does that correspond to a universa collapsing? No, it corresponds to stuff disappearing from our universe, unt…
Hawking radiation can't just be stuff dissapearing, because the actual singularity can dissolve. Besides, where would the stuff even leave from? I could imagine the mass flux through our event horizon being related to the energy driving space expansion (or contraction). That only makes sense if time on the inside is related to time on the outside though. The idea that any mass that will ever fall into our black hole…
Yes but this is not a completely alien idea. We know that things that are moving through space with 100% of their movement through space (i.e., moving at the speed of light), 0% of their movement is through time.
Take a proton for example. From the proton’s perspective, its creation and destruction happen in the same instant. From our perspective, it may travel through space for some period of time between the two events.
We’re not completely sure about the nature of gravity, but given how gravity seems to interact with spacetime, it seems at least plausible that time outside the singularity compresses to a single instant from the perspective of someone inside the event horizon.
Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#46Earlier quoted context omitted.
Black holes need not be dense. The black hole at the centre of galaxy M87 has the density of air in our atmosphere. The larger the black hole, the less dense it is. So that alone doesn't preclude us existing inside of one.
That’s news to me, I was taught that the mass collapses into it self it creates more gravity and more matter gets sucked in because the mass is so dense. So at which point does it become less dense?
As long as it’s dense enough that light can’t escape, it’s a black hole. You can achieve that with extreme density or huge volumes of mass. The more massive an object, the less dense it needs to be to be a black hole.
Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#47Earlier quoted context omitted.
There is no absolute direction for a galaxy’s spin—it’s always relative to the observer’s perspective. So I’d suspect they’re saying time and distance would need to be factored in rather than just looking at static images relative to our position today since our own spin may have caused a particular galaxy to appear to have been spinning in a different direction at another point in space-time
I don't understand this logic. To me, that's equivalent to saying "there's no absolute direction for which way a wheel spins, it's relative to the speed of the observer". Which makes no sense to me, because my definition of spin is measured against the axis of rotation of the object itself. I don't see how time-intermittent frame captures from our own position affect that interpretation. Or are we using an astonomy-s…
It's true, there is no absolute direction for which way a wheel spins. It's relative to the observer.
If you are standing on the side of a road, and a bicycle goes by, then you may observe the wheels to rotate clockwise, while an observer on the other side of the road will observe the same wheels to rotate counter-clockwise.
The sun is said to rotate around the centre of the milky way galaxy once every 225 million years. Over that time frame, some of the galaxies we observe will flip between clockwise and counterclockwise rotation as our viewpoint changes.
But that isn't relevant here. The Space article is too vague and handwavy to make any conclusions about the research, and should be ignored. Only the original scientific paper is worth reading: https://academic.oup.com/mnras/article/538/1/76/8019798?logi...
Section 5.2 "Physics of Galaxy Rotation" seems particularly relevant.
> due to the Doppler shift effect galaxies that rotate in the opposite direction relative to the Milky Way are expected to be slightly brighter than galaxies that rotate in the same direction relative to the Milky Way. Therefore, more galaxies that rotate in the opposite direction relative to the Milky Way are expected to be observed from Earth, and the difference should peak at around the Galactic pole. That observation is conceptually aligned with the empirical data of Fig. 10, and the observation using JADES described in Section 3.
You should read the paper for the full argument.
Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#48Earlier quoted context omitted.
I'm utterly confused what's going on. They're measuring galaxies' rotations by looking at images of the subset that are spiral galaxies, and checking which direction the arms spiral. They describe their image processing algorithm in their paper [0]. (it's around figure 3) How can local movement of stars within the Milky Way affect which way spiral galaxy arms are pointing? [0] https://academic.oup.com/mnras/article/5…
There is no absolute direction for a galaxy’s spin—it’s always relative to the observer’s perspective. So I’d suspect they’re saying time and distance would need to be factored in rather than just looking at static images relative to our position today since our own spin may have caused a particular galaxy to appear to have been spinning in a different direction at another point in space-time
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Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#49An alternate hypothesis which seems equally interesting, albeit for different reasons, is at the end of the article: > Another explanation for why the JWST may have seen an overrepresentation of galaxies rotating in one direction is that the Milky Way's own rotation could have caused it. > Previously, scientists had considered the speed of our galaxy's rotation to be too slow to have a non-negligible impact on observ…
This is the simpler explanation. Or they need better measurements. The black hole theories are more “fun” but not logically consistent and there’s no shred of evidence beyond science fiction level ideas
Re: Is our universe trapped inside a black hole? This JWS Telescope discovery
#50i have always been wondering if the added up velocities of a series of rotating sub-systems has a relativistic effect that impacts what we observe and measure. the moon is rotating itself, around the earth, which is rotating around the sun, which is rotating ...