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How can it make out galaxies at billions of light years away, but not a truck sized craft at a few million miles? I haven't done the math myself, so I'm certai

How can it make out galaxies at billions of light years away, but not a truck sized craft at a few million miles? I haven't done the math myself, so I'm certain one side of that equation is wrong, but that seems hard to believe!

dheerendra73 5y ago
Well galaxies at billions of light years distance are also 100000s light years wide. Rest of the math you can do about resolution now!
heavenlyblue 5y ago
It’s interesting that you are expressing an opinion about something that you could calculate in the same amount of time it took to write down that opinion.
- weaksauce 5y ago
  It seems like they are going for the "the easiest way to get a right answer is give the wrong answer on the internet" approach.
  - Spare_account 5y ago
    Cunningham's Law https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham's_Law%22 https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham'...
- Sebb767 5y ago
  To be fair, for someone who is not well-versed in either optics or space physics, calculating the answer is not that straight-forward.
  - kadoban 5y ago
    You can do pretty well just comparing the ratios of the size to the distance, right? Or is it more than that?
    - idealmedtech 5y ago
      That's a start, for sure, but to do a super accurate calculation (the kind I feel unqualified to carry out), you need to take into account apparent size, redshift, whether or not there's gravitational lensing, interstellar dust in the way, etc etc. But I want to reiterate that what's meaningful about this discussion is in part how unintuitive things at the far edges of our scales of perception really are. It's a muscle that, left untrained, will lead you to make incorrect characterizations like the one I made.
- idealmedtech 5y ago
  It's been over a decade since my last astrophysics class, but I appreciate you being charitable about my assumed knowledge! I think if anything this thread shows: 1) how absolutely mindblowingly big space is 2) how bad humans really are at intuiting things at the scale of space
Spare_account 5y ago
>a truck sized craft at a few million light years? JWST is three light seconds from earth
- idealmedtech 5y ago
  Awful typo on my part! Definitely face palmed when I caught it.
frosted-flakes 5y ago
Here's the math[1]. Seems believable to me. The Web telescope is miniscule conpared to faraway galaxies, and it doesn't emit much light. [1]: https://mobile.twitter.com/gfish/status/1479339620785524736 https://mobile.twitter.com/gfish/status/1479339620785524736
- idealmedtech 5y ago
  I did a little math of my own, and found that while the ratio of these distances is on the order of 10^15, the ratio of the sizes of these objects is on the order of 10^19. In other words, Webb is only one TEN THOUSANDTH the apparent size of a galaxy that's a _billion light years away_ That's just mind numbing to consider!
jibalt 5y ago
galaxy_width / truck_width = 3 × 10^20

dheerendra73 5y ago

Well galaxies at billions of light years distance are also 100000s light years wide. Rest of the math you can do about resolution now!

heavenlyblue 5y ago

It’s interesting that you are expressing an opinion about something that you could calculate in the same amount of time it took to write down that opinion.

weaksauce 5y ago
It seems like they are going for the "the easiest way to get a right answer is give the wrong answer on the internet" approach.
- Spare_account 5y ago
  Cunningham's Law https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham's_Law%22 https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham'...
Sebb767 5y ago
To be fair, for someone who is not well-versed in either optics or space physics, calculating the answer is not that straight-forward.
- kadoban 5y ago
  You can do pretty well just comparing the ratios of the size to the distance, right? Or is it more than that?
  - idealmedtech 5y ago
    That's a start, for sure, but to do a super accurate calculation (the kind I feel unqualified to carry out), you need to take into account apparent size, redshift, whether or not there's gravitational lensing, interstellar dust in the way, etc etc. But I want to reiterate that what's meaningful about this discussion is in part how unintuitive things at the far edges of our scales of perception really are. It's a muscle that, left untrained, will lead you to make incorrect characterizations like the one I made.
idealmedtech 5y ago
It's been over a decade since my last astrophysics class, but I appreciate you being charitable about my assumed knowledge! I think if anything this thread shows: 1) how absolutely mindblowingly big space is 2) how bad humans really are at intuiting things at the scale of space

Spare_account 5y ago

>a truck sized craft at a few million light years? JWST is three light seconds from earth

idealmedtech 5y ago
Awful typo on my part! Definitely face palmed when I caught it.

frosted-flakes 5y ago

Here's the math[1]. Seems believable to me. The Web telescope is miniscule conpared to faraway galaxies, and it doesn't emit much light. [1]: https://mobile.twitter.com/gfish/status/1479339620785524736 https://mobile.twitter.com/gfish/status/1479339620785524736

idealmedtech 5y ago
I did a little math of my own, and found that while the ratio of these distances is on the order of 10^15, the ratio of the sizes of these objects is on the order of 10^19. In other words, Webb is only one TEN THOUSANDTH the apparent size of a galaxy that's a _billion light years away_ That's just mind numbing to consider!

jibalt 5y ago

galaxy_width / truck_width = 3 × 10^20