[hmorgan]

I've found that when I have a thought that seems to contradict the "established" model of the world, I tend to just be missing some critical factor. A recent example is when I thought: "why don't we just use physical objects to communicate information? Wouldn't that be instantaneous?" Turns out, no, pushing on one end of an object only communicates information to the other end at the speed of sound. Not intuitive when you only think about observable experience (it sure seems like if I push a steel bar, the other end moves instantly), but that's how the world works.

In the case of your thought experiment, the critical factor is that our eyes are able to observe and adjust to a very wide range of brightness in different conditions. Sirius A really is billions of times dimmer than the sun to our eyes (hard to find a good reference for that, but this mentions it: https://ecampus.matc.edu/mihalj/astronomy/test5/stellar_magn...).

[zarmin]

Your steel bar example isn't analogous. You had an intuition, discovered a physical constraint (speed of sound), and the math checked out. The constraint explained the phenomenon. What would it look like if the "established" model of the world were actually wrong?

Here, the math doesn't check out. That's my point.

I'm not saying "it seems like stars should be invisible but they're not", Im showing that inverse square law - which we can verify at human scales - predicts invisibility at stellar distances, and the proposed compensation (25x more luminosity) is insufficient by orders of magnitude.

Sirius is "billions of times dimmer" than the sun to our eyes IF you mean the Sun as seen from Earth versus Sirius as seen from Earth. But that's not the comparison. The comparison is:

Sun moved to 544,000 AU (Sirius's distance): 296 billion times dimmer than Sun at 1 AU Sirius at 544,000 AU: 25x brighter than that

25x doesn't bridge a 296-billion-fold gap, plus the eye's dynamic range is irrelevant; we're comparing what brightness should reach the eye versus what compensation the model claims.

If your claim is "the eye can see across many orders of magnitude, so even though the Sun would be invisible at stellar distances, Sirius being slightly brighter makes it visible," then do the actual calculation. Show that 25x more luminosity produces enough photons to cross the detection threshold. Because the math I'm showing says it doesn't.

You're assuming the model works and looking for why my intuition is wrong. I'm showing the model's numbers are internally inconsistent. Those aren't the same thing.

>I've found that when I have a thought that seems to contradict the "established" model of the world, I tend to just be missing some critical factor.

Does it bother you that to make relativity work, they had to invent dark matter and dark energy - 96% of the universe's mass-energy - as fudge factors? At what point does "missing a critical factor" become "the model requires constant patching to match observations"?

[ceejayoz]

> Does it bother you that to make relativity work, they had to invent dark matter and dark energy - 96% of the universe's mass-energy - as fudge factors? At what point does "missing a critical factor" become "the model requires constant patching to match observations"?

This would be a lot more compelling from someone who doesn't believe in astrology.

https://news.ycombinator.com/item?id=45631792

(It's interesting that you forget the inverse square law in that case.)

[hmorgan]

I think I see what you mean now, but what makes you think that the sun would be invisible at 544,000 AU?

Here are the numbers as far as I understand them.

Apparent magnitude of the sun: -26.74 Apparent magnitude of Sirius A: -1.46

Excepted magnitude of the sun after moving to 544,000 AU: 296 billion times weaker, leading to +1.96 magnitude, according to a calculator (https://www.1728.org/magntude.htm).

I don't trust that calculator a lot, so to check that math, I used a formula to calculate the difference between those magnitudes (https://lco.global/spacebook/distance/comparing-magnitudes-d...) and got a result of 23.34. Not far off from the expected 25x difference.

So the sun at 544,000 AU wouldn't make the top 25 brightest stars in the night sky, but it wouldn't be far from that (https://www.britannica.com/science/list-of-brightest-stars-2...) and definitely well within what would be visible (https://en.wikipedia.org/wiki/Limiting_magnitude).