4 ms·

Yes, it's possible but the refractive index decreases with increase in wavelength to the point that this would not be feasible. Radio wavelengths are ~9 orders

Yes, it's possible but the refractive index decreases with increase in wavelength to the point that this would not be feasible. Radio wavelengths are ~9 orders of magnitude larger than optical, meaning the detector would need to be placed roughly 30 light years from earth. A bit out of our reach. (assuming I did my back of the envelope math right)

ur-whale 4y ago
Uh, never realized that gravitational lensing was stronger for higher frequencies ... is that a fact? Any reference? [EDIT]: the formula on page 4 of the book below does not seem to have a frequency parameter ... Also, they seem to consider that objects worth looking at are at infinity, which is why there is a well-defined focal distance from the sun. What seems to involve frequency is that the gain of the lens varies (same book, page 9). http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20Space%20Flight%20and%20Communications_%20Exploiting%20the%20Sun%20as%20a%20Gravitational%20Lens_%20Claudio%20Maccone_%202009.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20...
- spacemark 4y ago
  Oops my bad, thought this was a comment under another thread discussing terrestrial lensing which uses Earth's atmosphere, not gravitational lensing. Disregard!
DennisP 4y ago
I wonder whether any stars 30 light years away have interesting objects behind them.
sp332 4y ago
But we're using a lens that bends spacetime. I'm not sure index of refraction is relevant. On the recent image from JWST, I don't see any refraction artifacts on the lensed images of galaxies. https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-...
- spacemark 4y ago
  Oops my bad, thought this was a comment under another thread discussing terrestrial lensing which uses Earth's atmosphere, not gravitational lensing. Disregard!

ur-whale 4y ago

Uh, never realized that gravitational lensing was stronger for higher frequencies ... is that a fact? Any reference? [EDIT]: the formula on page 4 of the book below does not seem to have a frequency parameter ... Also, they seem to consider that objects worth looking at are at infinity, which is why there is a well-defined focal distance from the sun. What seems to involve frequency is that the gain of the lens varies (same book, page 9). http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20Space%20Flight%20and%20Communications_%20Exploiting%20the%20Sun%20as%20a%20Gravitational%20Lens_%20Claudio%20Maccone_%202009.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20...

spacemark 4y ago
Oops my bad, thought this was a comment under another thread discussing terrestrial lensing which uses Earth's atmosphere, not gravitational lensing. Disregard!

DennisP 4y ago

I wonder whether any stars 30 light years away have interesting objects behind them.

sp332 4y ago

But we're using a lens that bends spacetime. I'm not sure index of refraction is relevant. On the recent image from JWST, I don't see any refraction artifacts on the lensed images of galaxies. https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-...

spacemark 4y ago
Oops my bad, thought this was a comment under another thread discussing terrestrial lensing which uses Earth's atmosphere, not gravitational lensing. Disregard!