I feel like I am going into the field of philosophy. Whether or not you are shown that fairies are real has no being on whether they are. Hey – and if they are not real, then how do you explain fairy dust? That last sentence used my sense of humor, which I hope you appreciate.
Obtain, and read, E. T. Jaynes’ Probability Theory: The Logic of Science. Learn about Bayes theorem and how to relate prior, marginal, joint, conditional, and prior probabilities and learn how they relate to evidence and a rational way of altering degree of belief in arbitrary propositions.
You are inverting the order of things. One proposes “perhaps fairies exist”. That’s fine. But there is literally no reason to believe that this proposition (or any other proposition concerning the real world) is true without evidence that it is true. Note that this is precisely what we do in science. “Perhaps magnetic monopoles exist” or “Perhaps gravitons exist” to cite two particular named species of so-far invisible fairy.
In both cases there are at least some reasons to think that they might, as the hypotheses have at least limited explanatory power, just as invisible but maleficent fairies with cute little wings instead of wild onions in a field or various bacteria in a septic environment could be responsible for turning the cow’s milk sour. But until you catch an invisible fairy in a fairy trap and spray it with black paint to make it visible, or catch a graviton in a graviton trap or a monopole in a monopole trap, rational people will not waste a lot of mental energy on belief that any of these fairies are real. That’s precisely the line for religious thinking in science as well as anything else. If I believe too strongly in monopoles without direct evidence, I naturally become inclined to interpret all sorts of things as being caused by monopoles and eventually stop being a scientist, I become a crank who twists the evidence insensibly to fit the theory instead of the other way around.
Otherwise, how can one reasonably decide between competing claims? There are an infinite number of mutually contradictory propositions one can frame about the real world. Nearly all of them are false. How can we reasonably home in on the almost invisibly small set (and yet still infinite — of measure zero if you know what that means) of propositions that are more likely than the rest be true, and home in further still to the ones that are most likely to be true?
In my opinion, it is “on the basis of the evidence, subject to a global consistency requirement for the entire ontology”. To a truly religious person it is “on the basis of what I want to believe, regardless of whether there is global consistency or evidence to support my beliefs”. One is right because it works, the other wrong because it doesn’t. It’s as simple as that.
rgb
rgbatduke says:
December 17, 2013 at 11:39 am:
“You are inverting the order of things.”
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The “truth” of whether or not Fairies exist was there “before” anyone started trying to find the truth. It is not be that is inverting the order of things.
Correction of a typo. I meant to write: The “truth” of whether or not Fairies exist was there “before” anyone started trying to find the truth. It is not ME that is inverting the order of things.
Richard D
December 17, 2013 2:07 pm
E. T. Jaynes’ Probability Theory: The Logic of Science. Learn about Bayes theorem and how to relate prior, marginal, joint, conditional, and prior probabilities and learn how they relate to evidence and a rational way of altering degree of belief in arbitrary propositions.
+++++++++++++++++++++++++++++++++++=
Thanks for the tip, and the seminars throughout this thread.
Correction of a typo. I meant to write: The “truth” of whether or not Fairies exist was there “before” anyone started trying to find the truth. It is not ME that is inverting the order of things.
The Universe contains an enormous amount of information. That information content is further organizable into still more higher order information — structural and functional meta-information if you like. You are a subset of the Universe. Your information content is a lot smaller. Human “knowledge” is a representation of a high-order feature decomposition of the (generally but not exclusively) exterior “not me” part of the Universe. Indeed, from our cognitive point of view, we are “in” the Universe and trying to learn about the reality we are “in” (including, in part, ourselves).
I (at least in MY experience) did not come with much preprogrammed knowledge. Nearly everything I know I have learned by information transfer across some sort of boundary between “me” and “not-me”. The aggregate of consistent, high-level organized information that I have built up over living 59+ years as a single entity with some sort of continuity of existence (according to my imperfect memory of affairs) is what we might call “stuff I know”, or more precisely “stuff I think is very likely to be true” about the Universe. Some of this knowledge may be precisely true, some may be approximately true, some may be approximately false, some may be perfectly false, some of it may be knowable, and almost all of what there is to be known is fundamentally unknowable by me if even in fact my knowledge of physics (which I think is very probably true) is, in fact, at least approximately true and correct. Indeed, information theory states quite clearly that one cannot encode the information content of a larger system uniquely in a smaller one without entropic loss (or prior knowledge in the form of assumptions that one generally cannot prove).
Now of course I cannot speak for you in this matter. Perhaps you were born with perfect innate knowledge. Perhaps you were not even born. I have pretty serious beliefs that you were indeed born and, like me, were born in a state of nearly perfect ignorance about the world into which you were born. Are we in agreement here? Because if you were not born or know things about fairies a priori or have a higher order pathway to “truth” that doesn’t involve altering the internal biological state of your brain, then we probably are never going to achieve communication here, and I’ll move on.
If OTOH, you are, like me, a pilgrim soul making sense of the aggregate information that comes into our “senses”, then you have the order backwards. The Universe is an objective reality in which pink unicorns or invisible fairies in fact exist or do not exist, agreed. However we literally can never be certain either way! No experience you could have would suffice to prove that they really exist and an external material object — no experience you can have suffice to prove the existence of an external material reality in the first place!
The best we can do is agree on how we arrive at the best possible answer to the question “Do pink unicorns (really!) exist”. Granted that we will never be certain, it seems foolish to conclude that it is probably true that they exist without some consistent evidentiary pathway supporting the assertion that they do. Sure, they could exist somewhere nobody can see them — maybe Europa is heavily populated with pink unicorns, or maybe they live inside an unexplored extinct volcano cauldron in Tibet and nowhere else. But even if we could see them, they still might not exist — we could all be power units in The Matrix where all of our senses are systematically deceived.
Just as Candide finally concluded that the best way to proceed through life is to tend one’s own garden, I have to say that I think that the best way to build an epistemology is believe the most that which we can doubt the least, given the evidence and a consistent set of evidence based knowledge — basically stuff that is consistent with our aggregate sensory experience — rather than believing in things for which there is NO evidence in preference to things for which there is lots. This leaves a terrible infinity of possible truths that are unknown or perhaps even unknowable, and a single Universe that is in some sense fundamentally unknowable except through inference based on our sensory stream. All of these unsupported but possibly true assertions fall into the general category of “things one probably shouldn’t waste belief in until evidence supporting their probable true emerges in my sensory experience in some consistent, believable way”.
On the dark side of the moon, there could be a rock the exact size and shape of Abraham Lincoln’s head, carved out by accident so that the resemblance is uncanny, right down to the beard and eyebrows. It could be true! It doesn’t even contradict a single law of physics for it to be true!
Well, except for one. The second law of thermodynamics. When you understand the second law (especially from an information theoretic perspective), you’ll understand why you have things backwards.
rgb
@rgb 2:31 pm I (at least in MY experience) did not come with much preprogrammed knowledge.
A person’s “boot sector” is an enourmous amount of code. Granted, much of it is firmware, but there is so much code in operation at birth, we only have a vague inventory of the subroutines. The visual Input bus alone is a daunting bio-electrical process beyond our collective capability to understand let alone duplicate.
I realize your key word is “knowledge”. Which somehow implies a bright line between what we learn how to do and what we can do inately. I don’t think there is a bright line. Imagine how much programming we would need to write to bootstrap the routine to recognize a face much less recognize any approximate pattern rendered between maculas and visual cortex.
Yet somehow, it is all comes encoded in our DNA.
…. and maybe some stuff we don’t know about.
That is just another tickle of the Sense of Mystery.
rgbatduke says:
December 17, 2013 at 2:31 pm
+++++
Please step back and realize that you’re responding in a way that I think does not address the point I am making.
I’ll make it simple for you so we can end the back and forth. Let’s assume that Fairies do not exist. This is my assumption anyway, that they do not exist.
OK – so let’s agree for the sake of argument that Fairies do not exist.
The fact that Fairies do not exist, existed before the any scientific research took place. The research did not make it so, it may have eased the minds of those whom wanted to know.
Yet somehow, it is all comes encoded in our DNA.
…. and maybe some stuff we don’t know about.
That is just another tickle of the Sense of Mystery.
Encoded in our DNA I’m good with. Even associated with the developmental process in the womb. If the “some stuff we don’t know about” is hypothesized to include information flow from some non-material source, though, the “maybe” becomes “almost certainly not, disbelieve until given some reason to do otherwise”. Not that this codicil isn’t there on anything at all we believe. One can never rule anything out completely because lack of evidence isn’t evidence of lack.
rgbatduke says:
December 17, 2013 at 2:31 pm
…”The best we can do is agree on how we arrive at the best possible answer to the question ”
+++++++++
You’re being practical, and describing how to use science (as I do in many facets of my work) to come up with solutions to problems. Science works. I get it.
If we could only get human kind to do so [ agree on how we arrive at the best possible answer to the question] in large numbers. Oh – wait, we have gotten human kind to agree in large numbers. There was a time when the world was for a fact, flat. It was undeniable. There was a time where the sun traveled around the world –fact. This happened at the pinnacle of mankind’s understanding of all sorts of things.
The agreement has no affect on whether something is true or not. But agreeing and moving forward is more practical than philosophizing (which is what I guess I was doing 🙂
There is a reason that smart people can disagree in large numbers. Some people still believe in Fairies, witches, and that we are headed for a climate tipping point due to CO2.
You and I are on the same side of this debate.
Mario Lento at 8:30 pm There was a time when the world was for a fact, flat.
At the scale of a square acre, the world IS flat. It is the terrain that is lumpy.
See “The Relativity of Wrong” by Isaac Asimov. There was a time where the sun traveled around the world –fact.
There was a time when we THOUGHT the sun traveled around the world. And if it was only the Sun and Earth we needed to consider, it would be a workable model. It is when you need to explain the movements of Venus, Mars, Mercury, Jupiter, and Saturn that a different model becomes desirable. Want to visit Saturn with a 5-ton Cassini explorer with a VVEJ gravity assist trajectory, then even a sun-centered model isn’t quite good enough and you must refer to a Solar System Barycenter.
Sleepalot
December 18, 2013 7:56 am
Gunga Din says: December 16, 2013 at 3:16 pm
“There is no “natural” way to prove there is no such thing as “supernatural”.”
Nor is there any need to.
Stephen Rasey says:
December 17, 2013 at 9:35 pm
Mario Lento at 8:30 pm
There was a time when the world was for a fact, flat.
At the scale of a square acre, the world IS flat. It is the terrain that is lumpy.
See “The Relativity of Wrong” by Isaac Asimov.
There was a time where the sun traveled around the world –fact.
There was a time when we THOUGHT the sun traveled around the world. And if it was only the Sun and Earth we needed to consider, it would be a workable model. It is when you need to explain the movements of Venus, Mars, Mercury, Jupiter, and Saturn that a different model becomes desirable. Want to visit Saturn with a 5-ton Cassini explorer with a VVEJ gravity assist trajectory, then even a sun-centered model isn’t quite good enough and you must refer to a Solar System Barycenter.
++++++++++
You prove my point PERFECTLY. At the point we knew for a fact that the sun does not go around the earth! Dare I say even a consensus agrees. MY POINT IS THAT that “discovery” had no affect on whether the sun goes around the earth. The truth exists whether or not anyone realizes it whether through pure science or religion. What is just is.
I submit to you that 100 years from now, we are going to discover things that many today thought were fact. Our feelings about these things will not have changed what is and was.
I submit to you that 100 years from now, we are going to discover things that many today thought were fact. Our feelings about these things will not have changed what is and was.
I think we are all in agreement here. The whole point of science is that it is an ongoing process. One never achieves complete certainty. However, this does not really have to lead to Hume’s “epistemological catastrophe” where we cannot derive truths about the real world or prove (by derivation) that we can reliably infer truths about the real world, but one can agree to accept a set of unprovable assumptions/axioms (such as the Cox-Jaynes axioms) and use them as the basis of a derivation of a theory of scientific inference that does justify and even quantify the use of inference and evidence as a best basis for unprovable beliefs about the real world. In part this merely describes what we all do anyway — it quantifies “common sense”. However, there are advantages to putting the process on a formal footing — one obtains the Bayesian theory of statistics, information theory, statistical mechanics in physics all for “free” on the coattails of a small, remarkably powerful set of axioms.
It is also formally defensible as a basis for epistemology — instead of defending inference or falsification or verification or divinely revealed truthism per se, one only has to defend the reasonableness of the axioms, and since they manifestly ARE the basis for mere common sense, it is rather difficult to disagree with them and appear sane or propose an alternative that is more reasonable. That’s what I was trying to point out to Janice — she currently lives in an epistemological Universe with two distinct standards for probable truth. One applies to religion and spiritual/ethical matters, and an entirely different one applies to matters of fact, to scientific matters, to legal matters, to everything else but religion. Indeed, it is usually the case that even religious matters are partitioned, and one uses one standard for one’s own religion and the other standard for all of the other religions.
In one of the two worlds, one cannot twist the facts to fit the theory. In the other, one can do nothing else. I’ve had an extended discussion with a Christian who believed that the Bible was inerrant truth (just as Cardinal Saint Bellarmine clearly did, as revealed in his letter to Galileo back in 1612 or thereabouts). I tried to explain how we know that the Universe is older than 6000-10000 years, that there was no world-spanning flood, that life evolved. We went through radiometric dating and the use of parallax and so on (I teach astronomy from time to time so I can actually walk through EXACTLY how we know a lot of these things) but his counter-argument was very simple. He was happy to concede all of the observational data I liked, but none of it mattered. The Bible was Literally True, period! If its statements contradicted the conclusions of physics, so much the worse for physics. We obviously had it all wrong.
This in a nutshell is the fundamental problem with the religious cognitive/epistemological dichotomy. At one point or another it must separate itself from the usual cognitive epistemological rules. Even the Catholic Church, infamous for its opposition to nearly every important advance in science over many, many centuries (and sure, it wasn’t all bad and occasionally made contributions of its own) has had little choice but to accept the scientific epistemology as the correct basis for truth but has carefully and jealously carved out its own special exception as the sole authority on moral truths and religious truths which are safely beyond any possibility of empirical contradiction or affirmation. At some point all of the actual world religions require you to believe something not because there is reliable, reproducible evidence that would convince anybody but because they say so! Or some antique religious scripture of uncertain provenance says so.
There isn’t a single world religion that worships God — they all worship scripture. They worship ritual. They worship authority. Without it, there is nothing. (Well, OK, the Quakers might be an exception, sometimes. But I have little beef with Quakers — you can even be an atheist Quaker if that’s the way your heart moves you). Sadly, there is a certain amount of this mindset in at least the public presentation of climate research. We have replaced the oracle of holy scripture with the oracle of the GCM. We have replaced Bellarmine’s: Second. I say that, as you know, the Council [of Trent] prohibits expounding the Scriptures contrary to the common agreement of the holy Fathers. And if Your Reverence would read not only the Fathers but also the commentaries of modern writers on Genesis, Psalms, Ecclesiastes and Josue, you would find that all agree in explaining literally (ad litteram) that the sun is in the heavens and moves swiftly around the earth, and that the earth is far from the heavens and stands immobile in the center of the universe. Now consider whether in all prudence the Church could encourage giving to Scripture a sense contrary to the holy Fathers and all the Latin and Greek commentators. Nor may it be answered that this is not a matter of faith, for if it is not a matter of faith from the point of view of the subject matter, it is on the part of the ones who have spoken. It would be just as heretical to deny that Abraham had two sons and Jacob twelve, as it would be to deny the virgin birth of Christ, for both are declared by the Holy Ghost through the mouths of the prophets and apostles.
with the “97% of all scientists agree that CAGW is an accomplished fact” argument. We no longer to care whether or not the GCMs are working — it would be just as heretical to deny that these physics-based models are correct as it would be to deny the virgin birth of Christ, because both are declared true and correct by the Holy Ghost of Authority through the mouths of various authoritative prophets and apostles.
Personally I prefer Bertrand Russell (I’m a second generation disciple of Russell, as my guru of philosophy was one of Russell’s students): Even when the experts all agree, they may well be mistaken.
rgb
rgbatduke says:
December 18, 2013 at 11:58 am:
It’s perhaps not possible to separate religion from God for some. For others, God just is; -and religion is the manifestation of a set of behaviors related to scriptures or other historical documents. I once heard a wise person say, when people argue about religion, both sides are wrong. I hope we can agree 🙂
Now, back to figuring out which ORP sensors to use, and where measurements should be taken (for determining disinfection levels in treated water).
Richard D
December 18, 2013 5:33 pm
Good grief….work all day and I’m lost here, again….not that I can keep up with you learned posters here anyway…..Cheers to you all as I’ve enjoyed the discussion about meaningful beliefs/reality very much.
Richard D
December 18, 2013 6:02 pm
Can anyone be called a medical doctor?
++++++++++++++++++++++++++++++++++++++++
Sure…..after the rugby, beer and girls in premed go to med school for basic science, pass steps and clinical clerkships….then do “grad school” aka residency and boards then perhaps a fellowship.
BTW, I know more than a few who hold a BA including literature, history and philosophy….scary ones do philosophy or mathematics. I hold a BA, liberal arts……I bet I have as many or more undergraduate science credits as many who hold a BS.
Shout out to rgb…..I did general physics lecture/lab in summer school at university after sophomore year in prep school……Engineers….everywhere…..PLEASE GOD HELP ME>>>>
@richard D at 6:02 pm I did general physics lecture/lab in summer school at university after sophomore year in prep school……Engineers….everywhere…..PLEASE GOD HELP ME
You went to the right school. 😉
@Rgb (I teach astronomy from time to time so I can actually walk through EXACTLY how we know a lot of these things)
I’m an Astronomy Merit Badge councilor, so that is as close as I get to teach it. But I love how the history of science is so intertwined with astronomy. On a clear fall-winter night we can make out Andromeda. “Did you know the Universe is only 83 years old? Ok, the Universe is about 15 billion years old, but we didn’t know there was more than one galaxy until Ed Hubble in 1930 proved that fuzzy patch was not in the Milky Way and was another galaxy.”
I’m an Astronomy Merit Badge councilor, so that is as close as I get to teach it. But I love how the history of science is so intertwined with astronomy. On a clear fall-winter night we can make out Andromeda. “Did you know the Universe is only 83 years old? Ok, the Universe is about 15 billion years old, but we didn’t know there was more than one galaxy until Ed Hubble in 1930 proved that fuzzy patch was not in the Milky Way and was another galaxy.”
Astronomy is awesome to teach, even without the joy of viewings (I have my own 10″ Schmidt-Cassegrain with all the bells and whistles, although I don’t get to use it anywhere nearly as often as I would like as we live “in” Durham and there is too much haze except in the winter, and then it is cold…;-). Explaining how one can measure the distance to the nearest stars (start by measuring the distance to the Sun to get the base of a big triangle, then shoot precise lines to a “nearby” star in the evening, six months separated, to determine the angle in the apex as its apparent location shifts relative to the truly distant background stars, then do simple trig “parallax” to find the height of the triangle and/or distance to the star in parsecs. Explaining how knowing the distance and measuring intensity of the light from the star, we know its total output power. Explaining how we know its luminosity and temperature from its color and the Planck distribution and the Stephan-Boltzmann equation. Explaining how its luminosity and total power yield its cross-sectional area and hence its size. Plotting the color against the size for all the stars close enough to use parallax on (hundreds) to make the Hertzsprung-Russell diagram and begin to understand BOTH the life cycle of the star AND how one can determine luminosity as a function of color/type. Then inverting the process — using the color of a more distant star to determine its size, temperature, and luminosity, then using its measured intensity to determine the distance! Suddenly instead of being limited to a hundred parsecs or so (limits of parallax), we can determine the distance to every star we can see in the Milky Way! Using some of those stars — e.g. Cepheid variables — that are bright enough and characteristic enough to be seen even in other galaxies to create a still longer “meter stick” that allows us to measure the distances to galaxies. Using telescopes to learn that the Universe is absoloutely lousy with Galaxies and that they are huge — Andromeda is order of a million parsecs away, and subtends as much of the night sky as the moon! Hubble using the measured distance to a large set of “nearby” galaxies to discover that the Universe is expanding, and that the red-shift of spectral lines from distant, receding galaxies can become yet another meter stick, and suddenly the Universe is at least billions of years old and billions of light years across. Watching the life cycle of stars and galaxies themselves play out (distance equals time in the past, so sorting them out they make a “movie” of how galaxies and stars evolve in time). Discovering that our Sun is a third generation star some five billion years old — rich in “metals” (any element other than hydrogen and helium) and that we ourselves are made of stardust, forged in the heart of exploding stars, that the Earth is some 4.5 billion years old (radiometric dating of the rocks) and that life is almost as old, appearing remarkably shortly after temperatures dropped to where it was possible at all.
It’s a hell of a story, and every bit of it can be checked! You can do at least the first few steps yourself with equipment at least as good as that available to 19th century astronomers, for a few thousand dollars in personal investment or a trip to a nearby observatory and chatting up its astronomers. It isn’t scripture, it isn’t authority, it contradicts all scriptures of all religions to a greater or lesser extent (although apologists will ever find ways of twisting language to convince at least themselves that it doesn’t), and even though we have excellent reasons to think that the reasoning above is correct, it is still being investigated for consistency, accuracy, correctness, and things like the estimated size of the visible post-Big Bang Universe were still changing until a decade or so after the Hubble went aloft when they finally started to converge (basically, they had to make very precise measurements for their “standard candles” to extend the metrics to the edges of the visible Universe, at the end of “The Big Dark” post big-bang).
Since this is real science, it isn’t out of the question that there could be game changers out there — dark matter or energy, new physics, figuring out string theory. Even the Big Bang itself isn’t completely a done deal, although it is by far the most obvious explanation of the observations. You might well find a 97% (or even 100%) consensus among astronomers that the Big Bang is correct, but there are a number of unresolved issues — monopoles (where are they)? The observed matter/antimatter asymmetry. Flatness issues. And of course, we still lack a GUT that consistently handles things like quantum theory and gravitation and general relativity, which makes it difficult to answer all of the questions one might have about precisely how the BB might have worked.
Love it. Not my field, but hey, neither is climate science (although some days it feels like it).
rgb
@rgbatduke at 7:52 am
It is a shame that Astronomy is such a cold weather “sport.”
You covered a lot of subjects, but you left out one of my favorites: The AU.
Why do we measure the distance from the Sun in AU? Because via geometry we quickly found the distances of Mercury, Venus, Mars, Jupiter, Saturn as a ratio of the Sun-Earth distance.
But finding the Sun-Earth distance was REALLY hard. It was via the Transits of Mercury and Venus that we established that key baseline. You had to measure Venus’ shadow across the earth to simultaneously determine its diameter and relative velocity. Geometry problem: Isosolies triangle with known base length and opposite angle. This took exquisit timing across multiple places on the earth with synchronized clocks. And we needed to know the longitude of the places we measured it. All in the day when precise timing and longitude were edge of the envelope technology. With Venus, you got only 2 chances eight years apart every 113 years. Tricky.
It is a shame that Astronomy is such a cold weather “sport.”
Well, that’s not always a bad thing. Unless you have a big scope (> 18-20″) you really can’t see much of galaxies or nebulae with your eye, they just aren’t bright enough. I learned this when I got my first scope, and figured out I couldn’t see star clusters and such like I saw in pictures. Unless, you have a big scope or take long exposure images(or both). Digital cameras are what got me into imaging, faint objects really need long exposures or darker skies than what i have(or once again both). And the colder it is the longer exposure you can take without getting a lot of thermal noise that you have to process out. Some of my best pictures were captured with 12 minute exposures @ur momisugly about 5F. Fortunately you can spend an hour or so getting everything setup, and then go inside while it captures data.
@MiCro
Great photo. When all you have is an eyeball, it is easy to see why it was called a “Planetary Nebula” and completely misjudge size and distance.
Oh, and I was wrong about 1930. Hubble found the Cepheids in 1925
Oh, let me drag this back a little more on topic.
To remove thermal noise from your images, you take a number of “Dark” frames, a number of exposures of the same length as your “Light” frames , that you average together into a statistically averaged thermal noise map, this then gets subtracted as you stack your light’s, removing the noise. But Darks have to be taken at the same temp as lights, and if you log the temp, you can create a library of darks so you don’t have to waste a lot of precious imaging time not collecting photons.
So I started logging temperatures on clear sky nights, starting just after dark to well into the night, and I became more and more bothered by how much the temp dropped after dark, through all of that heat retaining Co2………..
@MiCro 1:52 pm.
Thanks for the skilled tip. To clarify…
You Stack the Lights
You Stack the Darks (for the same temps as the lights)
You subtract the Stacked Darks from the Stacked Lights.
What software do you use? Photoshop?
That’s it basically. You can also add bias frames (Darks (lens cap on) for the shortest exposure which collects the pixel and read circuit noise), and flats non-saturated exposures of a uniform field (the day time sky works) which captures optical field flatness. I use a Shareware program called DeepSkyStacker to process all of my subs (stack and then adjust levels since the program has the full range of fractional values) then I do a little bit of polishing (curves, and final level adjustments) in Photoshop.
There’s a great book “The Handbook of Astronomical Image Processing” by R. Berry and J. Burnell that has all the gory details, and the Forums @ur momisuglyhttp://www.cloudynights.com has a treasure of info as well.
I’ve been using Canon DSLR’s, which have great low noise sensors, and there are some excellent cooled astro cameras available.
Capturing photons is pretty straight forward, making the optics track a single spot in the sky to within a few pixels is the hard part. You need a high quality German Eq. mount, and depending how good it is you may also need a guide scope that you lock on to a star and servo the mount to point in one spot. I use another shareware program called PhD Guiding for that. They even have ways to guide out the turbulence of the atm.
This is how you do deep sky imaging, different objects (planets, Solar, orbital) need whole different approaches as well as possibly completely different equipment. But I’ve always like Galaxies, Nebulae, and blown up stars. I even have a low quality before and during Supernova in M101.
Oh, you also catch cosmic ray events, if you go to my link and look up all the articles, you find one there on that topic.
I feel like I am going into the field of philosophy. Whether or not you are shown that fairies are real has no being on whether they are. Hey – and if they are not real, then how do you explain fairy dust? That last sentence used my sense of humor, which I hope you appreciate.
Obtain, and read, E. T. Jaynes’ Probability Theory: The Logic of Science. Learn about Bayes theorem and how to relate prior, marginal, joint, conditional, and prior probabilities and learn how they relate to evidence and a rational way of altering degree of belief in arbitrary propositions.
You are inverting the order of things. One proposes “perhaps fairies exist”. That’s fine. But there is literally no reason to believe that this proposition (or any other proposition concerning the real world) is true without evidence that it is true. Note that this is precisely what we do in science. “Perhaps magnetic monopoles exist” or “Perhaps gravitons exist” to cite two particular named species of so-far invisible fairy.
In both cases there are at least some reasons to think that they might, as the hypotheses have at least limited explanatory power, just as invisible but maleficent fairies with cute little wings instead of wild onions in a field or various bacteria in a septic environment could be responsible for turning the cow’s milk sour. But until you catch an invisible fairy in a fairy trap and spray it with black paint to make it visible, or catch a graviton in a graviton trap or a monopole in a monopole trap, rational people will not waste a lot of mental energy on belief that any of these fairies are real. That’s precisely the line for religious thinking in science as well as anything else. If I believe too strongly in monopoles without direct evidence, I naturally become inclined to interpret all sorts of things as being caused by monopoles and eventually stop being a scientist, I become a crank who twists the evidence insensibly to fit the theory instead of the other way around.
Otherwise, how can one reasonably decide between competing claims? There are an infinite number of mutually contradictory propositions one can frame about the real world. Nearly all of them are false. How can we reasonably home in on the almost invisibly small set (and yet still infinite — of measure zero if you know what that means) of propositions that are more likely than the rest be true, and home in further still to the ones that are most likely to be true?
In my opinion, it is “on the basis of the evidence, subject to a global consistency requirement for the entire ontology”. To a truly religious person it is “on the basis of what I want to believe, regardless of whether there is global consistency or evidence to support my beliefs”. One is right because it works, the other wrong because it doesn’t. It’s as simple as that.
rgb
Sorry, one of the first [two] “priors” should have been “posterior”. I’m coming down off of a four day grading jag.
rgb
rgbatduke says:
December 17, 2013 at 11:39 am:
“You are inverting the order of things.”
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The “truth” of whether or not Fairies exist was there “before” anyone started trying to find the truth. It is not be that is inverting the order of things.
Correction of a typo. I meant to write: The “truth” of whether or not Fairies exist was there “before” anyone started trying to find the truth. It is not ME that is inverting the order of things.
E. T. Jaynes’ Probability Theory: The Logic of Science. Learn about Bayes theorem and how to relate prior, marginal, joint, conditional, and prior probabilities and learn how they relate to evidence and a rational way of altering degree of belief in arbitrary propositions.
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Thanks for the tip, and the seminars throughout this thread.
Correction of a typo. I meant to write: The “truth” of whether or not Fairies exist was there “before” anyone started trying to find the truth. It is not ME that is inverting the order of things.
The Universe contains an enormous amount of information. That information content is further organizable into still more higher order information — structural and functional meta-information if you like. You are a subset of the Universe. Your information content is a lot smaller. Human “knowledge” is a representation of a high-order feature decomposition of the (generally but not exclusively) exterior “not me” part of the Universe. Indeed, from our cognitive point of view, we are “in” the Universe and trying to learn about the reality we are “in” (including, in part, ourselves).
I (at least in MY experience) did not come with much preprogrammed knowledge. Nearly everything I know I have learned by information transfer across some sort of boundary between “me” and “not-me”. The aggregate of consistent, high-level organized information that I have built up over living 59+ years as a single entity with some sort of continuity of existence (according to my imperfect memory of affairs) is what we might call “stuff I know”, or more precisely “stuff I think is very likely to be true” about the Universe. Some of this knowledge may be precisely true, some may be approximately true, some may be approximately false, some may be perfectly false, some of it may be knowable, and almost all of what there is to be known is fundamentally unknowable by me if even in fact my knowledge of physics (which I think is very probably true) is, in fact, at least approximately true and correct. Indeed, information theory states quite clearly that one cannot encode the information content of a larger system uniquely in a smaller one without entropic loss (or prior knowledge in the form of assumptions that one generally cannot prove).
Now of course I cannot speak for you in this matter. Perhaps you were born with perfect innate knowledge. Perhaps you were not even born. I have pretty serious beliefs that you were indeed born and, like me, were born in a state of nearly perfect ignorance about the world into which you were born. Are we in agreement here? Because if you were not born or know things about fairies a priori or have a higher order pathway to “truth” that doesn’t involve altering the internal biological state of your brain, then we probably are never going to achieve communication here, and I’ll move on.
If OTOH, you are, like me, a pilgrim soul making sense of the aggregate information that comes into our “senses”, then you have the order backwards. The Universe is an objective reality in which pink unicorns or invisible fairies in fact exist or do not exist, agreed. However we literally can never be certain either way! No experience you could have would suffice to prove that they really exist and an external material object — no experience you can have suffice to prove the existence of an external material reality in the first place!
The best we can do is agree on how we arrive at the best possible answer to the question “Do pink unicorns (really!) exist”. Granted that we will never be certain, it seems foolish to conclude that it is probably true that they exist without some consistent evidentiary pathway supporting the assertion that they do. Sure, they could exist somewhere nobody can see them — maybe Europa is heavily populated with pink unicorns, or maybe they live inside an unexplored extinct volcano cauldron in Tibet and nowhere else. But even if we could see them, they still might not exist — we could all be power units in The Matrix where all of our senses are systematically deceived.
Just as Candide finally concluded that the best way to proceed through life is to tend one’s own garden, I have to say that I think that the best way to build an epistemology is believe the most that which we can doubt the least, given the evidence and a consistent set of evidence based knowledge — basically stuff that is consistent with our aggregate sensory experience — rather than believing in things for which there is NO evidence in preference to things for which there is lots. This leaves a terrible infinity of possible truths that are unknown or perhaps even unknowable, and a single Universe that is in some sense fundamentally unknowable except through inference based on our sensory stream. All of these unsupported but possibly true assertions fall into the general category of “things one probably shouldn’t waste belief in until evidence supporting their probable true emerges in my sensory experience in some consistent, believable way”.
On the dark side of the moon, there could be a rock the exact size and shape of Abraham Lincoln’s head, carved out by accident so that the resemblance is uncanny, right down to the beard and eyebrows. It could be true! It doesn’t even contradict a single law of physics for it to be true!
Well, except for one. The second law of thermodynamics. When you understand the second law (especially from an information theoretic perspective), you’ll understand why you have things backwards.
rgb
You can’t get work from blind faith.
@rgb 2:31 pm
I (at least in MY experience) did not come with much preprogrammed knowledge.
A person’s “boot sector” is an enourmous amount of code. Granted, much of it is firmware, but there is so much code in operation at birth, we only have a vague inventory of the subroutines. The visual Input bus alone is a daunting bio-electrical process beyond our collective capability to understand let alone duplicate.
I realize your key word is “knowledge”. Which somehow implies a bright line between what we learn how to do and what we can do inately. I don’t think there is a bright line. Imagine how much programming we would need to write to bootstrap the routine to recognize a face much less recognize any approximate pattern rendered between maculas and visual cortex.
Yet somehow, it is all comes encoded in our DNA.
…. and maybe some stuff we don’t know about.
That is just another tickle of the Sense of Mystery.
rgbatduke says:
December 17, 2013 at 2:31 pm
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Please step back and realize that you’re responding in a way that I think does not address the point I am making.
I’ll make it simple for you so we can end the back and forth. Let’s assume that Fairies do not exist. This is my assumption anyway, that they do not exist.
OK – so let’s agree for the sake of argument that Fairies do not exist.
The fact that Fairies do not exist, existed before the any scientific research took place. The research did not make it so, it may have eased the minds of those whom wanted to know.
Yet somehow, it is all comes encoded in our DNA.
…. and maybe some stuff we don’t know about.
That is just another tickle of the Sense of Mystery.
Encoded in our DNA I’m good with. Even associated with the developmental process in the womb. If the “some stuff we don’t know about” is hypothesized to include information flow from some non-material source, though, the “maybe” becomes “almost certainly not, disbelieve until given some reason to do otherwise”. Not that this codicil isn’t there on anything at all we believe. One can never rule anything out completely because lack of evidence isn’t evidence of lack.
rgbatduke says:
December 17, 2013 at 2:31 pm
…”The best we can do is agree on how we arrive at the best possible answer to the question ”
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You’re being practical, and describing how to use science (as I do in many facets of my work) to come up with solutions to problems. Science works. I get it.
If we could only get human kind to do so [ agree on how we arrive at the best possible answer to the question] in large numbers. Oh – wait, we have gotten human kind to agree in large numbers. There was a time when the world was for a fact, flat. It was undeniable. There was a time where the sun traveled around the world –fact. This happened at the pinnacle of mankind’s understanding of all sorts of things.
The agreement has no affect on whether something is true or not. But agreeing and moving forward is more practical than philosophizing (which is what I guess I was doing 🙂
There is a reason that smart people can disagree in large numbers. Some people still believe in Fairies, witches, and that we are headed for a climate tipping point due to CO2.
You and I are on the same side of this debate.
Mario Lento at 8:30 pm
There was a time when the world was for a fact, flat.
At the scale of a square acre, the world IS flat. It is the terrain that is lumpy.
See “The Relativity of Wrong” by Isaac Asimov.
There was a time where the sun traveled around the world –fact.
There was a time when we THOUGHT the sun traveled around the world. And if it was only the Sun and Earth we needed to consider, it would be a workable model. It is when you need to explain the movements of Venus, Mars, Mercury, Jupiter, and Saturn that a different model becomes desirable. Want to visit Saturn with a 5-ton Cassini explorer with a VVEJ gravity assist trajectory, then even a sun-centered model isn’t quite good enough and you must refer to a Solar System Barycenter.
Gunga Din says: December 16, 2013 at 3:16 pm
“There is no “natural” way to prove there is no such thing as “supernatural”.”
Nor is there any need to.
Stephen Rasey says:
December 17, 2013 at 9:35 pm
Mario Lento at 8:30 pm
There was a time when the world was for a fact, flat.
At the scale of a square acre, the world IS flat. It is the terrain that is lumpy.
See “The Relativity of Wrong” by Isaac Asimov.
There was a time where the sun traveled around the world –fact.
There was a time when we THOUGHT the sun traveled around the world. And if it was only the Sun and Earth we needed to consider, it would be a workable model. It is when you need to explain the movements of Venus, Mars, Mercury, Jupiter, and Saturn that a different model becomes desirable. Want to visit Saturn with a 5-ton Cassini explorer with a VVEJ gravity assist trajectory, then even a sun-centered model isn’t quite good enough and you must refer to a Solar System Barycenter.
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You prove my point PERFECTLY. At the point we knew for a fact that the sun does not go around the earth! Dare I say even a consensus agrees. MY POINT IS THAT that “discovery” had no affect on whether the sun goes around the earth. The truth exists whether or not anyone realizes it whether through pure science or religion. What is just is.
I submit to you that 100 years from now, we are going to discover things that many today thought were fact. Our feelings about these things will not have changed what is and was.
I submit to you that 100 years from now, we are going to discover things that many today thought were fact. Our feelings about these things will not have changed what is and was.
I think we are all in agreement here. The whole point of science is that it is an ongoing process. One never achieves complete certainty. However, this does not really have to lead to Hume’s “epistemological catastrophe” where we cannot derive truths about the real world or prove (by derivation) that we can reliably infer truths about the real world, but one can agree to accept a set of unprovable assumptions/axioms (such as the Cox-Jaynes axioms) and use them as the basis of a derivation of a theory of scientific inference that does justify and even quantify the use of inference and evidence as a best basis for unprovable beliefs about the real world. In part this merely describes what we all do anyway — it quantifies “common sense”. However, there are advantages to putting the process on a formal footing — one obtains the Bayesian theory of statistics, information theory, statistical mechanics in physics all for “free” on the coattails of a small, remarkably powerful set of axioms.
It is also formally defensible as a basis for epistemology — instead of defending inference or falsification or verification or divinely revealed truthism per se, one only has to defend the reasonableness of the axioms, and since they manifestly ARE the basis for mere common sense, it is rather difficult to disagree with them and appear sane or propose an alternative that is more reasonable. That’s what I was trying to point out to Janice — she currently lives in an epistemological Universe with two distinct standards for probable truth. One applies to religion and spiritual/ethical matters, and an entirely different one applies to matters of fact, to scientific matters, to legal matters, to everything else but religion. Indeed, it is usually the case that even religious matters are partitioned, and one uses one standard for one’s own religion and the other standard for all of the other religions.
In one of the two worlds, one cannot twist the facts to fit the theory. In the other, one can do nothing else. I’ve had an extended discussion with a Christian who believed that the Bible was inerrant truth (just as Cardinal Saint Bellarmine clearly did, as revealed in his letter to Galileo back in 1612 or thereabouts). I tried to explain how we know that the Universe is older than 6000-10000 years, that there was no world-spanning flood, that life evolved. We went through radiometric dating and the use of parallax and so on (I teach astronomy from time to time so I can actually walk through EXACTLY how we know a lot of these things) but his counter-argument was very simple. He was happy to concede all of the observational data I liked, but none of it mattered. The Bible was Literally True, period! If its statements contradicted the conclusions of physics, so much the worse for physics. We obviously had it all wrong.
This in a nutshell is the fundamental problem with the religious cognitive/epistemological dichotomy. At one point or another it must separate itself from the usual cognitive epistemological rules. Even the Catholic Church, infamous for its opposition to nearly every important advance in science over many, many centuries (and sure, it wasn’t all bad and occasionally made contributions of its own) has had little choice but to accept the scientific epistemology as the correct basis for truth but has carefully and jealously carved out its own special exception as the sole authority on moral truths and religious truths which are safely beyond any possibility of empirical contradiction or affirmation. At some point all of the actual world religions require you to believe something not because there is reliable, reproducible evidence that would convince anybody but because they say so! Or some antique religious scripture of uncertain provenance says so.
There isn’t a single world religion that worships God — they all worship scripture. They worship ritual. They worship authority. Without it, there is nothing. (Well, OK, the Quakers might be an exception, sometimes. But I have little beef with Quakers — you can even be an atheist Quaker if that’s the way your heart moves you). Sadly, there is a certain amount of this mindset in at least the public presentation of climate research. We have replaced the oracle of holy scripture with the oracle of the GCM. We have replaced Bellarmine’s:
Second. I say that, as you know, the Council [of Trent] prohibits expounding the Scriptures contrary to the common agreement of the holy Fathers. And if Your Reverence would read not only the Fathers but also the commentaries of modern writers on Genesis, Psalms, Ecclesiastes and Josue, you would find that all agree in explaining literally (ad litteram) that the sun is in the heavens and moves swiftly around the earth, and that the earth is far from the heavens and stands immobile in the center of the universe. Now consider whether in all prudence the Church could encourage giving to Scripture a sense contrary to the holy Fathers and all the Latin and Greek commentators. Nor may it be answered that this is not a matter of faith, for if it is not a matter of faith from the point of view of the subject matter, it is on the part of the ones who have spoken. It would be just as heretical to deny that Abraham had two sons and Jacob twelve, as it would be to deny the virgin birth of Christ, for both are declared by the Holy Ghost through the mouths of the prophets and apostles.
with the “97% of all scientists agree that CAGW is an accomplished fact” argument. We no longer to care whether or not the GCMs are working — it would be just as heretical to deny that these physics-based models are correct as it would be to deny the virgin birth of Christ, because both are declared true and correct by the Holy Ghost of Authority through the mouths of various authoritative prophets and apostles.
Personally I prefer Bertrand Russell (I’m a second generation disciple of Russell, as my guru of philosophy was one of Russell’s students):
Even when the experts all agree, they may well be mistaken.
rgb
rgbatduke says:
December 18, 2013 at 11:58 am:
It’s perhaps not possible to separate religion from God for some. For others, God just is; -and religion is the manifestation of a set of behaviors related to scriptures or other historical documents. I once heard a wise person say, when people argue about religion, both sides are wrong. I hope we can agree 🙂
Now, back to figuring out which ORP sensors to use, and where measurements should be taken (for determining disinfection levels in treated water).
Good grief….work all day and I’m lost here, again….not that I can keep up with you learned posters here anyway…..Cheers to you all as I’ve enjoyed the discussion about meaningful beliefs/reality very much.
Can anyone be called a medical doctor?
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Sure…..after the rugby, beer and girls in premed go to med school for basic science, pass steps and clinical clerkships….then do “grad school” aka residency and boards then perhaps a fellowship.
BTW, I know more than a few who hold a BA including literature, history and philosophy….scary ones do philosophy or mathematics. I hold a BA, liberal arts……I bet I have as many or more undergraduate science credits as many who hold a BS.
Shout out to rgb…..I did general physics lecture/lab in summer school at university after sophomore year in prep school……Engineers….everywhere…..PLEASE GOD HELP ME>>>>
@richard D at 6:02 pm
I did general physics lecture/lab in summer school at university after sophomore year in prep school……Engineers….everywhere…..PLEASE GOD HELP ME
You went to the right school. 😉
@Rgb
(I teach astronomy from time to time so I can actually walk through EXACTLY how we know a lot of these things)
I’m an Astronomy Merit Badge councilor, so that is as close as I get to teach it. But I love how the history of science is so intertwined with astronomy. On a clear fall-winter night we can make out Andromeda. “Did you know the Universe is only 83 years old? Ok, the Universe is about 15 billion years old, but we didn’t know there was more than one galaxy until Ed Hubble in 1930 proved that fuzzy patch was not in the Milky Way and was another galaxy.”
I’m an Astronomy Merit Badge councilor, so that is as close as I get to teach it. But I love how the history of science is so intertwined with astronomy. On a clear fall-winter night we can make out Andromeda. “Did you know the Universe is only 83 years old? Ok, the Universe is about 15 billion years old, but we didn’t know there was more than one galaxy until Ed Hubble in 1930 proved that fuzzy patch was not in the Milky Way and was another galaxy.”
Astronomy is awesome to teach, even without the joy of viewings (I have my own 10″ Schmidt-Cassegrain with all the bells and whistles, although I don’t get to use it anywhere nearly as often as I would like as we live “in” Durham and there is too much haze except in the winter, and then it is cold…;-). Explaining how one can measure the distance to the nearest stars (start by measuring the distance to the Sun to get the base of a big triangle, then shoot precise lines to a “nearby” star in the evening, six months separated, to determine the angle in the apex as its apparent location shifts relative to the truly distant background stars, then do simple trig “parallax” to find the height of the triangle and/or distance to the star in parsecs. Explaining how knowing the distance and measuring intensity of the light from the star, we know its total output power. Explaining how we know its luminosity and temperature from its color and the Planck distribution and the Stephan-Boltzmann equation. Explaining how its luminosity and total power yield its cross-sectional area and hence its size. Plotting the color against the size for all the stars close enough to use parallax on (hundreds) to make the Hertzsprung-Russell diagram and begin to understand BOTH the life cycle of the star AND how one can determine luminosity as a function of color/type. Then inverting the process — using the color of a more distant star to determine its size, temperature, and luminosity, then using its measured intensity to determine the distance! Suddenly instead of being limited to a hundred parsecs or so (limits of parallax), we can determine the distance to every star we can see in the Milky Way! Using some of those stars — e.g. Cepheid variables — that are bright enough and characteristic enough to be seen even in other galaxies to create a still longer “meter stick” that allows us to measure the distances to galaxies. Using telescopes to learn that the Universe is absoloutely lousy with Galaxies and that they are huge — Andromeda is order of a million parsecs away, and subtends as much of the night sky as the moon! Hubble using the measured distance to a large set of “nearby” galaxies to discover that the Universe is expanding, and that the red-shift of spectral lines from distant, receding galaxies can become yet another meter stick, and suddenly the Universe is at least billions of years old and billions of light years across. Watching the life cycle of stars and galaxies themselves play out (distance equals time in the past, so sorting them out they make a “movie” of how galaxies and stars evolve in time). Discovering that our Sun is a third generation star some five billion years old — rich in “metals” (any element other than hydrogen and helium) and that we ourselves are made of stardust, forged in the heart of exploding stars, that the Earth is some 4.5 billion years old (radiometric dating of the rocks) and that life is almost as old, appearing remarkably shortly after temperatures dropped to where it was possible at all.
It’s a hell of a story, and every bit of it can be checked! You can do at least the first few steps yourself with equipment at least as good as that available to 19th century astronomers, for a few thousand dollars in personal investment or a trip to a nearby observatory and chatting up its astronomers. It isn’t scripture, it isn’t authority, it contradicts all scriptures of all religions to a greater or lesser extent (although apologists will ever find ways of twisting language to convince at least themselves that it doesn’t), and even though we have excellent reasons to think that the reasoning above is correct, it is still being investigated for consistency, accuracy, correctness, and things like the estimated size of the visible post-Big Bang Universe were still changing until a decade or so after the Hubble went aloft when they finally started to converge (basically, they had to make very precise measurements for their “standard candles” to extend the metrics to the edges of the visible Universe, at the end of “The Big Dark” post big-bang).
Since this is real science, it isn’t out of the question that there could be game changers out there — dark matter or energy, new physics, figuring out string theory. Even the Big Bang itself isn’t completely a done deal, although it is by far the most obvious explanation of the observations. You might well find a 97% (or even 100%) consensus among astronomers that the Big Bang is correct, but there are a number of unresolved issues — monopoles (where are they)? The observed matter/antimatter asymmetry. Flatness issues. And of course, we still lack a GUT that consistently handles things like quantum theory and gravitation and general relativity, which makes it difficult to answer all of the questions one might have about precisely how the BB might have worked.
Love it. Not my field, but hey, neither is climate science (although some days it feels like it).
rgb
I’ve loved astronomy since I was 8-10. About 12 years ago I started doing astrophotography.
http://www.science20.com/sites/all/modules/author_gallery/uploads/1444101679-09132009_ps1900m.jpg
This is my picture of Andromeda, I collected almost 40 hours of exposures(5 min@ur momisugly a time), this is the best 19 or so hours.
My interest is Nebula’s and Galaxies.
http://www.science20.com/gallery/virtual_worlds follow the picture link mid-page.
[snip – this argument is getting old -give it a rest -mod]
@rgbatduke at 7:52 am
It is a shame that Astronomy is such a cold weather “sport.”
You covered a lot of subjects, but you left out one of my favorites: The AU.
Why do we measure the distance from the Sun in AU? Because via geometry we quickly found the distances of Mercury, Venus, Mars, Jupiter, Saturn as a ratio of the Sun-Earth distance.
But finding the Sun-Earth distance was REALLY hard. It was via the Transits of Mercury and Venus that we established that key baseline. You had to measure Venus’ shadow across the earth to simultaneously determine its diameter and relative velocity. Geometry problem: Isosolies triangle with known base length and opposite angle. This took exquisit timing across multiple places on the earth with synchronized clocks. And we needed to know the longitude of the places we measured it. All in the day when precise timing and longitude were edge of the envelope technology. With Venus, you got only 2 chances eight years apart every 113 years. Tricky.
Well, that’s not always a bad thing. Unless you have a big scope (> 18-20″) you really can’t see much of galaxies or nebulae with your eye, they just aren’t bright enough. I learned this when I got my first scope, and figured out I couldn’t see star clusters and such like I saw in pictures. Unless, you have a big scope or take long exposure images(or both). Digital cameras are what got me into imaging, faint objects really need long exposures or darker skies than what i have(or once again both). And the colder it is the longer exposure you can take without getting a lot of thermal noise that you have to process out. Some of my best pictures were captured with 12 minute exposures @ur momisugly about 5F. Fortunately you can spend an hour or so getting everything setup, and then go inside while it captures data.
@MiCro
Great photo. When all you have is an eyeball, it is easy to see why it was called a “Planetary Nebula” and completely misjudge size and distance.
Oh, and I was wrong about 1930. Hubble found the Cepheids in 1925
Oh, let me drag this back a little more on topic.
To remove thermal noise from your images, you take a number of “Dark” frames, a number of exposures of the same length as your “Light” frames , that you average together into a statistically averaged thermal noise map, this then gets subtracted as you stack your light’s, removing the noise. But Darks have to be taken at the same temp as lights, and if you log the temp, you can create a library of darks so you don’t have to waste a lot of precious imaging time not collecting photons.
So I started logging temperatures on clear sky nights, starting just after dark to well into the night, and I became more and more bothered by how much the temp dropped after dark, through all of that heat retaining Co2………..
@MiCro 1:52 pm.
Thanks for the skilled tip. To clarify…
You Stack the Lights
You Stack the Darks (for the same temps as the lights)
You subtract the Stacked Darks from the Stacked Lights.
What software do you use? Photoshop?
That’s it basically. You can also add bias frames (Darks (lens cap on) for the shortest exposure which collects the pixel and read circuit noise), and flats non-saturated exposures of a uniform field (the day time sky works) which captures optical field flatness. I use a Shareware program called DeepSkyStacker to process all of my subs (stack and then adjust levels since the program has the full range of fractional values) then I do a little bit of polishing (curves, and final level adjustments) in Photoshop.
There’s a great book “The Handbook of Astronomical Image Processing” by R. Berry and J. Burnell that has all the gory details, and the Forums @ur momisugly http://www.cloudynights.com has a treasure of info as well.
I’ve been using Canon DSLR’s, which have great low noise sensors, and there are some excellent cooled astro cameras available.
Capturing photons is pretty straight forward, making the optics track a single spot in the sky to within a few pixels is the hard part. You need a high quality German Eq. mount, and depending how good it is you may also need a guide scope that you lock on to a star and servo the mount to point in one spot. I use another shareware program called PhD Guiding for that. They even have ways to guide out the turbulence of the atm.
This is how you do deep sky imaging, different objects (planets, Solar, orbital) need whole different approaches as well as possibly completely different equipment. But I’ve always like Galaxies, Nebulae, and blown up stars. I even have a low quality before and during Supernova in M101.
Oh, you also catch cosmic ray events, if you go to my link and look up all the articles, you find one there on that topic.