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Physics, Astronomy & Cosmology / Re: Would a gigantic stick out of neutronium bend around the Sun?
« on: 21/02/2024 23:09:53 »
Hi.
The Schwarzschild radius of our sun is about 2.9 Km (information source : Science direct https://www.sciencedirect.com/topics/physics-and-astronomy/schwarzschild-radius because I couldn't be bothered to do the calculation myself). So let's say the curvature of space could be significant at ten times this distance ≈ 29 Km. If you were 29 Km away from the centre of a mass equal to our sun, then the curvature of space can be significant.
Now the actual radius of our sun is approximately 700 000 Km (information source: NASA https://science.nasa.gov/sun/facts/#hds-sidebar-nav-3).
As you can see 29 Km is a lot smaller than 700 000 Km. The curvature of space isn't going to be significant until you're inside the sun. As mentioned just above, once you're inside then you can't even consider the entire mass of the sun to be contributing any longer (Hollow shell theorem, only the bit of the sun more interior than the 29Km counts) - so the curvature of space still will not be significant even when you are at 29 Km from the centre of the sun. Overall, our sun is just no-where near dense enough to cause a significant curvature of space.
Summary: There is some (small) curvature of space close to the sun but it's on the scale of effect that can deflect some rays of light by a degree or two and that's all. It's nothing like enough to make a rigid straight rod that was pushed up close to it turn into a bent ring all the way around the sun.
LATE EDITING: Articles discussing the deflection of light rays passing close to our sun are talking about arc-seconds of deflection. 1 arc-second is just a small fraction of 1 degree.
You're talking about effects, curving space in some extreme way, that would really require a star like a Neutron star rather than the humble star that is our sun.
Best Wishes.
I offer ten thousand apologies for being clueless, again.That's no crime, none of us will know everything. It's also highly commendable that you are prepared to just come out and say something like that.
be it a witty reply,It wasn't meant to be witty in the sense of being downgrading, that was not my intention. I must apologise if that's how it seems. This is the main Physics, Astronomy and Cosmology section of the forum. In here replies should first and foremost be based on mainstream science. In other sections, like "Just Chat" or "New theories" the guidelines are less restrictive. I don't think it matters and I don't think you need to move your discussion. It's just important that you realise that @Bored chemist and @Eternal Student (me) were somewhat obligated to provide an answer based on mainstream science in the first instance.
Must this very long stick, out of a certain other alloy, be ripped apart for sure?No. Rigid bodies where there are inter-atomic forces holding the body together can get very close to the sun before tidal forces should tear them apart. Indeed they could get so close that they have entered the outer layers of the sun and from there in toward the very centre of the sun, the total gravity they experience is reduced (they will only experience a pull toward that bit of the sun that is still more inward toward the centre, the bit of the sun that is now forming a shell exterior to that rigid body can be ignored - see "the hollow shell theorem" if your interested). So they can get arbitrarily close to the centre of the sun without being torn apart by tidal forces - but other stuff like extereme temperature and pressure would be a problem if they are in the sun.
I thought that space is bent around the starYes but for our Sun the curvature of space is still quite small. For every mass there is a certain distance at which the curvature of space gets "out of hand". For convenience we'll say this distance is the Schwarzschild radius although you may consider that the curvature is already quite significant at some multiple of this distance, say twice the Schwarzschild radius. Just to be quite confident that we're in some space where curvature is really not too serious at all, let's take 10 times the Schwarzschild radius.
The Schwarzschild radius of our sun is about 2.9 Km (information source : Science direct https://www.sciencedirect.com/topics/physics-and-astronomy/schwarzschild-radius because I couldn't be bothered to do the calculation myself). So let's say the curvature of space could be significant at ten times this distance ≈ 29 Km. If you were 29 Km away from the centre of a mass equal to our sun, then the curvature of space can be significant.
Now the actual radius of our sun is approximately 700 000 Km (information source: NASA https://science.nasa.gov/sun/facts/#hds-sidebar-nav-3).
As you can see 29 Km is a lot smaller than 700 000 Km. The curvature of space isn't going to be significant until you're inside the sun. As mentioned just above, once you're inside then you can't even consider the entire mass of the sun to be contributing any longer (Hollow shell theorem, only the bit of the sun more interior than the 29Km counts) - so the curvature of space still will not be significant even when you are at 29 Km from the centre of the sun. Overall, our sun is just no-where near dense enough to cause a significant curvature of space.
Summary: There is some (small) curvature of space close to the sun but it's on the scale of effect that can deflect some rays of light by a degree or two and that's all. It's nothing like enough to make a rigid straight rod that was pushed up close to it turn into a bent ring all the way around the sun.
LATE EDITING: Articles discussing the deflection of light rays passing close to our sun are talking about arc-seconds of deflection. 1 arc-second is just a small fraction of 1 degree.
You're talking about effects, curving space in some extreme way, that would really require a star like a Neutron star rather than the humble star that is our sun.
Best Wishes.
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