Science
36 watchers
Nov 2023
5:37pm, 15 Nov 2023
41,559 posts
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Nellers
Thanks for that too, Silent Night Runner. That's another bit of the "standard candle" puzzle. I couldn't get how they could differentiate in the "Father Ted" way (small/far away!) but if it's based on similar behaviour patterns in a certain circumstance then that fits (although it must involve an enormous amount of gathered data to match to an exact event).
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Nov 2023
6:18pm, 15 Nov 2023
15,901 posts
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jda
I haven't checked all the links posted but some of the distance thing for stars is redshift of known frequencies (because stars generate particular frequencies). If you go back to the big bang everything was in one place so distance and speed are closely related. One of my first publications was "The influence of binary stars on dwarf spheroidal galaxy kinematics". Binary stars are pairs that orbit each other and thus can have wildly different velocities to the general matter they are surrounded by. It's related to the search for cold dark matter which is necessary to explain the observed dynamics. (This is my wife's PhD, not mine, but I helped with the mathematical modelling, that being my speciality. It was also 35 years ago.) Most of my career was spent in climate change research (itself a rather diverse field) but as a mathematical modeller I got to dabble in quite a range of other things before and around that, including high-voltage power station switchgear, agricultural economics, storm surges and tides around the UK, covid prediction and maybe one or two other things. |
Nov 2023
6:18pm, 15 Nov 2023
2,487 posts
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MudMeanderer
Do craft like voyager help with calculating the distance, by increasing the size of the base of the triangle, or is it still too small relative to the measured distance to make much difference?
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Nov 2023
7:20pm, 15 Nov 2023
6,104 posts
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Windsor Wool
jeez, since 1977 and until today I’ve thought that a parsec was a fictional measure… My chemistry involved quite a lot sitting in a dark lab for lengthy periods, sorry!! Just one more comment on the hard things thing. It’s not that I don’t get it. In fact, it’s having a reasonably deeply understanding of some biochemical stuff that, for me at least, makes it seem all the more incredible that they were not the result of some watchmaker’s actions. I get time-periods, I get evolutionary theory. Just saying that it’s hard for me to accept. Even as a deep non-believer. |
Nov 2023
8:17pm, 15 Nov 2023
48,468 posts
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HappyG(rrr)
My wonder is strong too ww. Jda that's all really cool work.  G
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Nov 2023
8:48pm, 15 Nov 2023
996 posts
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Silent Runner
I haven't checked all the links posted but some of the distance thing for stars is redshift of known frequencies (because stars generate particular frequencies). If you go back to the big bang everything was in one place so distance and speed are closely related. Yes, redshift is another method used for estimating distances, but it only becomes useful at very large scales. Within our local group of galaxies, all the galaxies are gravitationally bound to each other (i.e. they're not moving apart from each other as the universe expands) so their redshifts aren't related to their distances from us. At larger distances, where the galaxies are receding from us with the expansion of the universe, a higher redshift implies a greater velocity of recession, which implies a greater distance. But at those distances you're really measuring the distance for whole galaxies, rather than individual stars. It does sound like you've had a fascinating career, jda. |
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Nov 2023
9:00pm, 15 Nov 2023
997 posts
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Silent Runner
Do craft like voyager help with calculating the distance, by increasing the size of the base of the triangle, or is it still too small relative to the measured distance to make much difference? It certainly would help in principle, but I don't think Voyager would have the equipment on board to make those sort of measurements. I think the cost and complexity of sending the equipment needed to the outer regions of the Solar System would probably outweigh the benefits, when there are cheaper and easier ways of getting the same information. |
Nov 2023
3:51pm, 17 Nov 2023
29,832 posts
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fetcheveryone
Here’s a potential problem with this thread. I want to know what Red Shift is. I would ask, but I know I could Google it too. I’m imagining it’s something to do with the visible light spectrum, and how much it bends over distance due to *insert thing here*. Is that remotely close? |
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Nov 2023
3:53pm, 17 Nov 2023
48,510 posts
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HappyG(rrr)
Ambulance whizzing past you - goes Naaaaaauuuuuuoooowwww - (change in pitch = change in frequency, based on your relative speed to it / it to you). Same with light - can't remember if towards is higher or lower frequency, but red = lower frequency, blue is higher. Ta da.
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Nov 2023
3:54pm, 17 Nov 2023
29,833 posts
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fetcheveryone
I am remembering the term Doppler Effect.
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