For those wondering if we could get sharper images with JWST, here’s the previously imaged black hole (same angular size as our own) compared to a single pixel from Hubble’s wide field camera 3:
While it won't be able to image more sharply on its own, JWST can still help to constrain certain factors in their modeling, thus obtaining better images.
That's incredible science and engineering. The Reddit ask science thread said it would be akin to taking a photo of a donut on the moon. So impressive even if off by a lot.
JWST is nowhere near the caliber of telescopes necessary to resolve black holes. Very literally, we would need an optical telescope bigger than new york city to even make an attempt.
What about an array of space telescopes creating a kind of "virtual lens"? Putting aside the engineering scale and cost of such a project, would something like that even be possible? Or would that be pure science fiction?
It is possible in principle, but gets harder as wavelength of captured light gets smaller and so far it is done only for long radio waves on planet scale.
As others have mentioned, this is similar to how the event horizon telescope works today!
However, there’s no free lunch. By using arrays of telescopes instead of a single filled dish/mirror, they are missing a lot of information.
Imagine a telescope the size of the earth, but you only use light from a few dozen spots on the surface and let the rest fall through.
This is why they had to do all that complicated image reconstruction processing to create the image shown in the papers.
There are proposals for scientific missions utilizing the gravitational lensing of light around the Earth (or other planets) being fed into a network of satellites to do exactly this. And as another comment pointed out, the EHT already does this for imaging black holes, just with satellites on Earth.
Yes, basically a bunch of huge telescopes across the planet have their images combined to give an effective mirror size of the entire earth, so one satellite is not going to cut it (even including the fact that IR has a shorter wavelength).
There is so much post processing that the telescope resolution barely matters. Personally I'm skeptical of these images since the algorithms have a lot of data fitting to "what it should look like" built in to them.
Is the EHT "only" planet scale, or is it taking a second measurement 180 days later to increase the effective diameter of the virtual antennae to the width of the earth's orbit?
No, unfortunately those measurements have to be taken at the same time.
That said, as the Earth rotates the distance between any two pairs of antennas changes which can be used to add additional information to the images (those new pairs of measurements again have to be taken simultaneously).
From what I understand, this is less useful for looking at Sgr A* since the scene isn’t static and changes on a roughly 10 minute timescale.
The resolution of these telescopes is limited by diffraction, not by the number of pixels on the sensors. The achievable angular resolution is roughly the wavelength divided by the aperture diameter [1]. JWST works in the few µm wavelength range and has a 6.5 m aperture, such that the angular resolution is ~0.1 arcsec. The EHT works with 1.3 mm wavelength and has an effective aperture of roughly the earth diameter (~13000 km). This leads to an angular resolution of a few ten µarcsec which is more than 1000 times higher than that of JWST.
The edge should be quite sharp. Any deformation or movement in the edge will be smoothed extremely quickly, on timescales comparable to the light-crossing time of the object -- in this case ten seconds or so.
If you're a photon and you're in, you stay in. If you're out and heading out, you get out. (if you skim the surface, you might make an orbit and then leave :) ). It is that fact that makes the edge quite sharp.
I disagree. The edge of a BH is essentially an asymptote. While there is a mathematical bright line, when looking at it you should see light in all manner of red/blue-shifted colors near the event horizon. Since that light is coming in from a variety of directions it leaves in a variety of directions too. Everything would look soft and fuzzy around the edges. Out of focus.
Out of focus? I don't know about you but I find the black hole "edge" in the simulated images in Interstellar quite sharp.
(Or are you talking about resolving matter/light near the event horizon? In that case I agree – one won't really resolve any structures anymore due to light getting bent and redshifted in a myriad of ways.)
In case you weren't being rhetorical, the sun's edge would either be the chromosphere[0] or the corona[1], the corona being famously fuzzy and also quite bafflingly hot. The chromosphere is "smoother", but still very interesting on any given day [2].
this is sort of getting into the definition of black holes and event horizons. I don't think they really have solid surfaces, I would expect all imaging here to show fuzzy samples.
I couldn't really say for sure but I think macroscopically (viewed from a low-resolution telescope) it would look fuzzy, but close up, it would look very spiky and dynamic with all sorts of stochastic events happening.
I think you just sort of rephrased the question :) Also, if you have a photo of a tree, then there are infinitely many objects that will produce that photo; however, that doesn't make it a bad or worthless photo.
But I suppose you could be right for a single image from one angle, and I suppose that we don't get to see this particular object from many different angles.
See, e.g., https://www.stsci.edu/jwst/phase2-public/2235.pdf (although this was written when there was no image, certainly it would still be useful).