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The Astronomer Who Brought Us the Universe
StartsWithABang writes If all we were able to do was look up at the sky and see what we can see, no matter how powerful our instruments became, we would be extraordinarily limited in what we could learn about the Universe. But if we could know some intrinsic properties about what we were looking at, then simply by measuring things like how bright these objects appear, we could figure out the cosmic distance scale; all it would require is knowledge of a "distance indicator" or "standard candle." The very first one ever discovered — by Henrietta Leavitt — is not only still in use today, but taught us the galactic nature of the spiral nebulae and gave us the expanding Universe.
when we get there we'll see.
Well, here's where you open yourself up. Distance measurements benefit from longer baselines. The biggest one we have now is about 2AU wide. Take a picture now, wait 6 months, take a picture again when the earth is on the opposite side of the sun. If we have a base on mars, we can have a slightly wider baseline with earth and mars on opposite sides of the sun for a simultaneous measurement (can't do that now at all) and two martian orbital radii for non-simulataneous measurements about a year apart.
Now you might say: well why can't we do this with a remote probe? And the answer is, of course we can, but it's damn near impossible to be flexible if you launch a satellite into space where you can't get at it to change instruments or reconfigure it. And big mirrors in space aren't anywhere near as easy as big mirrors on the ground. That's why we still build billion-dollar telescopes on the ground, even though we launch billion-dollar telescopes into space. If you had an actual base on mars, with support staff and manufacturing capacity of the sort needed to maintain a remote outpost, you can now have astronomical instrumentation that costs just as much as a space-based platform or a little more, but is worth dozens of space telescopes because it's manned and has the magical property of reconfigurability, repairability, and flexibility in software as well as hardware. So yes, you can do things with manned systems that you cannot do with unmanned systems, especially when you're doing science.
Well, I'm certainly not posting from the 24th century. So you've got me there.
Simultaneous? Ain't no such thing...
Sure there is, for two observers in the same reference frame, even if separated by large distances.
Well, here's where you open yourself up. Distance measurements benefit from longer baselines. The biggest one we have now is about 2AU wide. Take a picture now, wait 6 months, take a picture again when the earth is on the opposite side of the sun. If we have a base on mars, we can have a slightly wider baseline with earth and mars on opposite sides of the sun for a simultaneous measurement (can't do that now at all) and two martian orbital radii for non-simulataneous measurements about a year apart.
Now you might say: well why can't we do this with a remote probe?
We are: It's called Gaia. The baseline isn't really the limiting factor, nor is mirror size: it's mostly about atmospheric distortion and instrument stability, both of which are vastly improved in space. Gaia will be able to do parallaxes to accuracy of 20 micro-arcseconds.
Oh no! There's a space nutter behind you. Run! Save yourself. I'll try to hold them off.
Take this tinfoil hat. It may keep them from corrupting you telepathically!
yes, I'm sure she worked in complete isolation, and developed everything by herself.
No, she was a part of a group consisting entirely of women under the management of Edward Pickering at Harvard Observatory, called at the time "Pickering's Harem" Despite her groundbreaking accomplishments, Leavitt was unable to obtain a faculty position at Harvard, entirely due to her gender.
Times have changed a lot since then, despite the efforts of ignorant douchebags like you.
Entanglement can't transmit signals. This is often misunderstood, but it's a big part of the reason why it seems so strange.
Not a sentence!
not even possible to realize 'same reference frame' except in an idealized classroom example unless the two observers are coexisting in the same spot
Clocks have been the established method for synchronizing measurements along a baseline
The atomic clocks used for GPS are world beyond the ones used on ships for navigation in ages past, and better clocks are constantly being created
Sure, it is not as fancy as entaglement, but sometimes a hammer is the only tool that you have
Wherever You Go, There You Are
The GPS devices that you use would like to differ with you
about anything other than the bafflingly irrelevant Wonderwall cover. What is that all about?
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The same happened to Marie Curie (you know, the only person to date to win two nobel prizes in different categories and the first to win two alltogether). She was not able to enroll in higher education in Poland because it was not accepting women. Luckily she went to Paris ...
I mean we've had the least competent person in the history of the US in the White House for 6 years because his dad was black
I'm fairly sure George W Bush's father wasn't black, and it was 8 years.
To have a right to do a thing is not at all the same as to be right in doing it
In any real world situation the effects, however minute, of the continually changing local gravitational field due to the motion of all mass and energy will affect the rate of local time and thus will confuse the concept of simultaneity. Only in an unreal highly static situation can you accurately define the idea.
Leavitt's discovery is on a par with Galileo's discovery of the moons of Jupiter in changing our view of the universe. It combined a brilliant insight, that all the stars in the Small Magellanic Cloud are at about the same distance from Earth, and a lot of hard work analyzing photographic plates. Her measurement tool is still the main one used to determine cosmic distances from beyond the range of stellar parallax out to nearby galaxies, and is used, in turn, to calibrate Type Ia supernova, the standard candle for probing deep into intergalactic space, and back to the Big Bang. Another example of women astronomers getting less recognition than they deserve is Jocelyn Bell, who discovered millisecond pulsars and whose thesis advisor won the Nobel Prize for that discovery.
The first online site whose interface is so horrible that I specifically check to see if links go there before refusing to click them.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
GP Said least competent.