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Comment by robotresearcher | Hacker News Reader

The title here and the first image in the article are annoyingly misleading.

The authors report being able to detect populations of many microbes that they genetically engineered to produce lots of detectable molecules and they sprayed in patches on top of the soil.

So this could be a valuable thing. But the damn article shows an aerial image inlaid with a microscope image with individual organisms resolved, which is very very far from what is reported here.

It’s science reporting. Science is cool already. There’s no need to give misleading hyperbolic impressions. Bah.

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That makes a lot more sense, otherwise the SNR from 90 meters away seems like it would be … enormous.

We can see Uranus from Earth which in on a similar size/distance order of magnitude :).

Actually the angular size of Uranus seen from earth is almost a million times larger than a microbe seen from 90m (not that TFA was about seeing a single microbe, or seeing a microbe at all for that matter).

Can we do the math? I know that burden's on me but I feel I might be wrong, my back of the napkin calculation puts them within 10-100x.

1 micrometer (1E-6) to 50,700 km (1E6)

90 meters (1E2) to 2.8 billion km (1E12)

Edit: Oh yeah but size/distance does not decay linearly ...

I was lazy and asked Claude, although I didn't check the math.

Uranus subtends a much greater angle than a microbe at 90 meters. Let me work this out: Microbe from 90 meters:

A typical bacterium is about 1-5 micrometers (let's say 2 μm = 0.000002 meters) Angular size = (size / distance) in radians = 0.000002 / 90 ≈ 2.2 × 10⁻⁸ radians Converting to arcseconds: ≈ 0.0000046 arcseconds

Uranus from Earth:

Uranus is about 2.6-3.2 billion km from Earth (depending on orbital positions) Its diameter is about 51,000 km At closest approach, Uranus subtends approximately 3.7 arcseconds Even at its farthest, it's still around 3.3 arcseconds

So Uranus appears about 800,000 times larger in angular size than a bacterium at 90 meters away! This is why we can see Uranus through telescopes (and technically with the naked eye under perfect conditions, though just barely), but we absolutely cannot see individual bacteria without a microscope—the angle they subtend is far, far too small for our eyes to resolve.

2.2 × 10⁻⁸ radians is 0.0045 arcseconds [1]. That answer is off by 3 orders of magnitude.

[1] https://frinklang.org/fsp/frink.fsp?fromVal=2.2*10%5E-8+radi...

So what would be the difference on magnitude between the bacteria and Uranus, then?

Edit: nvm, I just read your other comment.

Thanks.

That was the latest greatest Sonnet 4.5 ... not quite great enough evidentially.

I just asked it to "check the radians to arcsec conversions", and it realized the error.

"You're absolutely right!"

Angular size is proportional to size/distance, so the calculation you're trying to do is correct; however, 50700 km is more than 1e7 meters so the angular sizes differ by about 3 orders of magnitude.

A leading reason touted as evidence the moon landing was fake is that we can't see the stuff supposedly left on the moon. Once you start going into angular resolution and the physics of optics you've already lost the argument.

You don't "lose" an argument just because the other side doesn't have the attention span to understand what you are saying.

Sure, but you'll never win. So whether you want to call it "lose" the argument or just apply "lose" to the amount of time and/or your own sanity, it's still a loss. You will definitely not be changing the other party's mind.

There is but a sliver of atmosphere between Earth and Uranus... and all of the atmosphere between sensing apparatus and microbes 90m away. I am curious how moon would look like if there was the atmospheric scattering the entire way there. Or if would even be able to spot Mars / Venus if we had a constant 1 atm the entire way.

How could it be constant 1 atm all the way to the moon. Wouldn't having an atmosphere as thick as 240km mean the pressure on the surface would be much greater than 1 atm?

That is physically impossible, the point was to compare apples to apples. I.E. resolving 1 micrometer at 90 meters through 1atm vs resolving celestial objects through the same medium to compare light scattering effects.

I do agree- i hate when an article doesn't include a thumbnail that Google News might indicate includes, but in this case, they just buried the lede, which is slightly different, and sometimes just as annoying: https://substackcdn.com/image/fetch/$s_!PKJG!,w_1456,c_limit...

We updated the title to match the research paper, thanks.

It's a nose, they invented a nose for robots. That's pretty neat.

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