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Space Science

MAP Satellite Launch 47

Posted by michael from the detect-a-burrito-being-heated-at-10000-miles dept.
PineGreen writes: "Tomorrow, MAP Satellite is to be launched. MAP is the first space mission to measure Cosmic Microwave Background (CMB) fluctuations after the famous COBE who was first to detect fluctuations in the CMB. It is supposed to do the job with an unprecedented accuracy. There were several successful balloon experiments (Boomerang, Maxima) and interferometer experiments (VSA, DASI, CBI), some of which still haven't published their data. But of course, we are all waiting for the big European Planck mission in 2007. Measuring CMB fluctuations can tell us a lot about the universe in which we live, its constituents and its geometrical properties."
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MAP Satellite Launch More

MAP Satellite Launch

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  • abbreviations (Score:4)

    by jfinke ( 68409 ) on Saturday June 30, 2001 @03:38AM (#118519) Homepage
    I wonder if it is possible to use any more abbreviations in that story....
  • MAP was scheduled to launch last fall. The astronomy club I belong to does a winter lecture series. March of 2000 Dr. Niels Cornish (Physics Dept. at MSU) gave a talk about the physics involved and what they are looking for. It promises to provide considerable data about the early universe via a technique different from the bulk of the work done to date. Way cool stuff.

    I think, therefore, ken_i_m
  • I loved the quote from NASA that this was the "Earliest baby picture possible..."

  • L2 (Score:3)

    by Manhigh ( 148034 ) on Saturday June 30, 2001 @04:25AM (#118522)
    Forgot to mention this is the first mission to orbit Earth-Sun Lagrange Point 2, soon to be followed by Next Gen Space Telescope.
  • Are any of the networks or CNN planning on covering the launch? Yes, I realize that there will be a live video feed at http://countdown.ksc.nasa.gov/elv/ [nasa.gov], but for us poor souls stuck with dialup, that is not an option!
  • I don't know how soon the NGST will follow up after MAP -- as far as I know, the design has not yet been settled on.
  • The MAP launch is currently scheduled for June 30 2001 from pad 17B at 15:46:46 EDT. I plan to see it live from about 6 miles south, at a bar [katannas.com].

    One of the small perks of living in Melbourne, FL is that I get to watch stuff that goes on at the Cape. This should be an OK launch, the weather is nice so far today, but it may get cloudy by the time they get around to it. The best show, by far, is a night shuttle launch.
    JMR

  • Re:Big Bang or just a fizzle? (Score:3)

    by Anonymous Coward on Saturday June 30, 2001 @06:04AM (#118526)
    I wonder, does the existence of background radiation prove the idea of the Big Bang?
    Nothing can prove a theory correct. However, the existence of the CMBR is considered some of the strongest evidence in favor of Big Bang models.
    My doubt mainly stems from the fact that the Big Bang is essentially a relativistic theory whilst it makes claims on objects with small diameters. (Also my objection to black holes.)
    Do you think that relativity doesn't apply on small scales? The theory of quantum electrodynamics (verified to one part in 10 billion) would beg to differ. Of course, that's special relativity, not general, but general relativity isn't expected to break down until near the Planck scale (10^-34 meters). Thus, the discrepancy only becomes important near singularities -- i.e., the Big Bang and centers of black holes.

    As for black holes, general relativity is applicable at horizon-size scales, so there should be an event horizon (and thus black holes should exist), but we don't really know what goes on at the very center of a black hole. As for the Big Bang singularity, we don't know what goes on there either -- but Big Bang cosmology doesn't require there to be an actual singularity, just that the universe was once very small, dense, and hot.

    Probably someone in the crowd is a bit more clued in than I am and can point me to an interesting article that say, proves the existence of Black Holes
    Like I said, nothing can prove a theory correct. If you're looking for evidence in favor of black holes, there are all sorts -- ranging from the detection of extremely massive, compact, dark objects, to huge energy jets that are so strong that they can only be powered by gravity, not fusion or anything, to stuff falling onto these dark compact objects that dim out of sight instead of producing the huge explosion we'd expect if they rammed into the surface of a neutron star at relativistic speeds, to the destabilization of orbiting matter at the location just outside the horizon where general relativity predicts no stable orbits can exist, and so on.
    - that, for all intents and purposes, will resolve my objection that a relativistic model cannot answer what is fundamentally in the realm of quantum theory.
    I don't think you understand what you're objecting to. Simple dimensional analysis tells you that quantum mechanics isn't important on scales of a few kilometers (the size of the smallest stellar black holes), any more than quantum mechanics is important when you're driving to work. It's a regime in which classical physics is highly applicable. Thus, it doesn't affect the formation of event horizons and things. It may affect the formation of a singularity in the center, but that's only well after an event horizon forms. And if an event horizon forms, it's by definition a black hole, regardless of whether there's a singularity in the middle. (Of course, quantum mechanics is important for Hawking radiation, but you get Hawking radiation even when quantum mechanics isn't affecting the gravitational physics very much -- just when the gravitational physics is affecting the small vacuum fluctuations. This is the "semiclassical approximation" where you can ignore the backreaction of quantum matter onto spacetime geometry because its effects are so small.)
    An alternative to the Big Bang, to explain the radiation could be that simply the enormous pressure at some point set off these waves.
    "At some point"? We receive the CMBR extremely uniformly from every direction in the sky. Why would there be this "enormous pressure" at some particular point in space? (Note that the Big Bang was not "an explosion" at some specific point in space, but rather the expansion of all of space from a point.) And why would "some enormous pressure at a point" generate perfect blackbody radiation? Apart from the background radiation, how do you explain the fact that the universe is expanding, and has been for as far back as we can see? What do you extrapolate from that about the early size of the universe? How do you explain the fact that the background radiation was once much hotter, in every direction we can see? How do you account for the observered ratios of light-element nuclesynthesis? Etc. etc.
    Perhaps the universe expands and contracts in a sinusoidal manner, but never actually becomes a singularity.
    That's possible, in a sense. Classically, there's no way for that to happen -- you have to "fine tune" the conditions to a ludicrously precise degree in order to get a bounce; the Penrose/Hawking singularity theorems show that under realistic generic conditions, it will never happen -- you'll get a classical curvature singularity. (And even if you do get a bounce, the bounces don't last for very long.) On the other hand, it is possible that if the universe crunches down to the Planck scale, then quantum gravity effects will take over and produce a "bounce". However, that doesn't rule out Big Bang models, because as I said above, all that cosmologists actually assume about those models is that the universe was once small, dense, and hot.

    The idea that there actually was an initial singularity is something that a lot of cosmologists doubt, but the media seems to equate that with "Big Bang cosmology". In reality, the existence of a singularity is what general relativity predicts, but nobody expects general relativity to apply at the Planck scale due to, as you say, quantum effects.

  • Re:Big Bang or just a fizzle? (Score:5)

    by jafuser ( 112236 ) on Saturday June 30, 2001 @06:21AM (#118527)
    Ok, I am not an astrophysicist, but I did just get the highest score in my astronomy class (by a margin of 10% even) :)

    The general temperature of the cosmic background radiation is evidence of the big bang. I think it was something close to 2.7 degrees Kelvin. This temperature is a minimal black body temperature which exists everywhere in the universe, no matter which direction we look. Apparently the uniformity of this tells us that as the universe is expanding, that the temperature will go down. So someone looked at this and figured out that if you play the expansion in reverse, that as the universe was smaller, this background temperature would have to be higher, eventually focusing on the big bang.

    When we use very sensitive equipment and draw an image from measurements of this black body radiation, we at first can see an effect caused by doppler shift becuase our planet is moving through space. Space seems hotter in the direction we are going, and cooler in the direction we are coming from.

    Finally, if we adjust for this doppler effect, and look at the temperature at even much higher accuracies (something like millionths of degrees) we start to see a nonuniform image of random warmer and cooler spots across space.

    One major significance of this is that if we measure the average distance between the cooler and warmer spots, we can compare this to a mathematical model which will tell us the curvature of space itself (on a very large scale) . If they match a mathematical model of flat space, then space is probably flat. If the patterns are larger or smaller than the flat model then space is probably curved, either hyberbollically or spherically.

    Of course, a non-flat space has some interesting consequences. The angles of a triangle don't add up to 180 degrees, and parallel lines will not stay equidistant (they may merge or converge) as they due in euclidian geometry.

    This satellite will provide a higher resolution image than COBE.

    I just woke up so I probably left out something important or really said something stupid...

    --

  • 1) I missed your post since you're an "Anonymous Coward". You should log on.

    2) Re: At some point.
    In time, of course.

    3) Of course the universe was hot and dense at some point (in time), but what interests me is the existence of a singularity. If the universe didn't come out of a singularity then it always existed (as I believe is the case).

    As far as predicting experimental results and so forth, it is enough to say the less than 10^-34 is not really significant, but when trying to answer a fundamental question like, was the universe created at the time of the Big Bang, or was this merely another event in the history of the universe?

    As for Black Holes: well, yes, I guess if all you want is an event horizon then I have no objections, but as I said, what really interests me is the singularity.

    4) Re: I don't think you understand what you're objecting to.
    That's a pretty quick judgement.

  • PS When I said "prove" I did not mean it in the strict mathematical sense of the word. Let's not get into such arguments, interesting as they are.
    We can take it as a give that "prove" means "provide convincing evidence to a model for which no evidence to the contrary has been found".
  • Speaking of triangles, here's a riddle:
    Suppose that the universe were hyperbolic, does that mean that the triangles we draw on paper have angles that add up to more than 180 degrees?

    Don't answer too quickly.

  • Your SPOO has way too much FLEEM, in fact, if you were cosmic radiation we could tell time my measuring your relative fleeminess.

    Have a nice day.

  • Well, Slashdot, that "tomorrow" is actually "today" at 1546 EDT
  • The existance of black holes can be proven several ways. 1.) When an object gravitationally bends or lenses light from another star, measurements of that can be used to determine the mass and density of the object. If it is much to heavy and compact to be a neutron star, it must be a black hole. 2.) When matter falls into an alleged black hole, it becomes brighter and brighter as it speeds up, but then becomes dimmer due to gravitational red shift, then disappears. There is no other explanation for this phenomenon than the existance of a black hole.
  • I would have thought they could have made mention that it was set to launch ASAP. (tomorrow)
  • Supposing that space is continuous the universe could not have a beginning if not from a singularity.

    As I said, I'm more interested in the existence of actual singulariries, but since the term black hole is more readily understood I used that as (perhaps not the best chosen) replacement.
    It might do you well not to assume that a person is an idiot before the conversation gets underway.

  • It [paper triangle > 180?] is a trick question... I'll let it sit there for a while.
  • If the universe didn't come out of a singularity then it always existed


    "Always" implies for all time. Time did not exist prior to the Universe, thus you'd be correct. Remember, the Big Bang theory states that not only was all the matter in the universe created, but the space the universe is in, as well as time, were created as well.


    Nothing existed before the universe. In the words of RockBiter, "A hole would be something, this was Nothing."


    This is pretty much impossible to imagine, since there is nothing to hook our imaginiations to. Much like imaging what happens to you after you die if there is no afterlife.



  • Am I the only one who read that headline and went HUNH??? geez...

    DJ
  • Basically so that we can figure out were everything came from, where it is and where it's going in a manner that does not require an invisible man whom created everything and thus knows where everything came from, where it is and where it's going.

    That's why.
  • Day after day, making tomorrow seem like yesterday!

  • No kidding, I always thought CMB" stood for Cosmic Microwave Burrito.

    (Taco Bell has its own space program you know...)
  • I think you are confused about what is a singularity. Which is alright, since we don't really know what is a singularity.

    A singularity is predicted by General Relativity, which is a classical theory, and we don't have confidence that GR works at very small scales. So we don't really know what happens at the infinitisimal small scales of a singularity.

    So don't worry too much. Be interested about it's existence. But be careful when you try to apply unknown physics and make claims about the eternal existence of the universe (which we don't know the answer to, yet).

    (am not the A.C. you refer to, of whom btw I think know a ton about this stuff so you should listen to him/her.)


    SEX!s.e.x.Sex.53X!sex.Si-Ee-Eks
  • abbreviations? i could have sworn they were acronyms. of course geeks would NEVER be known to have an affinity to acronyms, right?
  • Cosmology is not the subject for you if your requirement for proof is "no contrairy evidence" our abilities to observe the universe are strictly limited© "evidence" for odd events and the inexplicable is rather common, and many of the most well respected theories are really just gross extrapolation, they're very good educated guesses, but could easily be wrong©

    It's an interesting theory, but in all science, I'd say Cosmology and Particle Physics have got to be the areas where we are most likely to be proven very wrong within 50 years©
  • Yes, but its rather like worrying about the scale of a flat map of your neighborhood being off because of the curvature of the Earth© I would imagine that the effects of such curvature are only observable on inter-stellar or inter-galactic spaces©

    Of course curved space on a universal scale is one of those things I can't really wrap my head around© Imagining a 3D space ¥not even counting the effects on time and microdimentions twisted in 4D so that every point in the space follows hyperbolic curvature isn't too easy of a task without resorting to analogies©
  • "Like I said, that's not true. There's no logical reason why the universe couldn't have come into existence at a finite size or density."

    Let's not get into Russell type arguments and stick with simple math if you don't mind. Continuous functions do not contain discontinuities, simple as that.

    "I did assume that you didn't understand what you were objecting to.."

    And why is that? Because I see it differently? Can you infer that I lack understand merely from the fact that I prefer to stress certain points that I feel are more interesting than what you may feel? But I digress...

  • "It's a trick question if one assumes that you intentionally meant >180 instead of 180 in an attempt to trick people. Otherwise, stop trying to be cute and say what you mean"

    I'm not trying to trick anyone, I saw an opportunity to give a neat puzzle, take it if you like them, and don't assume the worst of people, you're having a bad day with it. (Put down the toy. Down. Good. ;) )

    I'm tempted to put down my answer, but naah, it'll be interesting to see what comes of it.

  • ""Always" implies for all time. Time did not exist prior to the Universe, thus you'd be correct. "

    I'd give you a 5-insightful if I knew where I put my marbles^H^H^H^H^H^H^H mod points.

    I'll have to think about this for a while.
    I'd like to say that that was not what I meant, and that you're twisting what I said around, but maybe it's not you doing the twisting, but space-time itself.

    A tad too deep for a witty comeback.

  • "I say your an idiot. Its pretty obvious that you know nothing about what your talking about here, and pretending to really makes you look like an idiot to those of us who do understand what this means."

    1) Erm, flaming?
    2) Now you see the obvious problem of being AC, I don't know if it's you or some other AC that's flaming.
    3) What the hell do you know about what I know???

  • "I think you are confused about what is a singularity."

    Not at all, I study math, and am pretty good at it, a singularity is a point which does not belong to the space. (I say the because here I am refering to any space.)

    If we think of space as being bent by gravity then we can think of space (or bending thereof) as a continuous function and singularities would naturally be the poles (points where the value of the function is infinite - in other words, the point does not belong to the range, ie space)

    "So we don't really know what happens at the infinitisimal small scales of a singularity."

    This is exactly my point.

  • "Yes, but its rather like worrying about the scale of a flat map of your neighborhood being off because of the curvature of the Earth© I would imagine that the effects of such curvature are only observable on inter-stellar or inter-galactic spaces©"

    So? I thought this was supposed to be like a geeky place, you know, where one might go to such lengths as take into account the curvature of the earth in order to improve one's driving.

    But seriously, to a mathematician it is fundamentally important to know if a number is exactly zero, or just close. No matter how close.

  • Oops, domain of course (not range) - got caught between thoughts.
  • AC your answer to the puzzle is incorrect, I'm giving other readers a chance at it. So don't you be childish.

    BTW You completely ignored my Russell comment and just continue on your safe and narrow path of assuming that I don't know what I'm talking about.

  • ...of the universe starting as anything other than a singularity is equivalent to that it will end in a state that which is not a singularity, which could mean at any moment in the near future. Clearly such ideas do not belong in the realm of science, no matter how plausible they seem.

  • Some References (Score:3)

    by Old-Claimjumper ( 463905 ) on Saturday June 30, 2001 @04:08PM (#118555)

    I realize that I am breaking some rule or other by posting actual information, but here are two good book for the non-PhD Cosmologist to get an introduction to the current topic.

    The First Three Minutes, Steven Weinberg, Basic Books, 1977
    ISBN : 0-465-02435-1

    This is one of the first books to explore the physics behind the 2.73 degree Background Radiation in a way that mere mortals could understand. The Physics at the time couldn't explain before a few milliseconds into the big bang, but Weinberg did a good job of explaining what we knew and how we knew it from the first few milliseconds up to the first three (and a half...) minutes. Steven Weinberg went on to win a Nobel Prize and also explain how Electromagnitism and the Weak force are actually the same early on in the game.

    At the other end of the spectrum is a brand new book that takes the unique approach of focusing on the concepts of Zero and Nothing and showing just how much follows. It ends up giving a good up-to-date view of the same physics as The First Three Minutes, but from a current viewpoint. I think that just a wee bit more Math describing the inflationary phases of the early universe and the idea of quantum pair production would have been appropriate, but for the most part the book is a good non-astrophysicist intro to the background radiation and the start of the universe as we know it twenty-some years after Weinberg's book.

    The Book Of Nothing, John D. Barrow, Pantheon, 2000
    ISBN : 0-375-42099-I

    Note, this would be a good book for a /. book reviews.

  • In Other News....HESSI Delayed Again (Score:3)

    by Renstar ( 142001 ) on Saturday June 30, 2001 @06:55PM (#118556) Homepage
    In a somewhat related story, NASA's [nasa.gov] HESSI [nasa.gov] (High Energy Solar SpectroScopic Imager) spacecraft has had its launch delayed again. It was supposed to launch July 4th 2000 but had to have many of its insturments recailbarated at GSFC [nasa.gov] when JPL [nasa.gov] shattered the mounting brackets by mistake in a vibration test. [nasa.gov] After that, a problem in the Pegasus launch vehicle was discovered and had to be fixed, delaying launch until 3 weeks after the X43 failure. KSC [nasa.gov] and Orbital Sciences [orbital.com] (makers of the Pegasus) cleared HESSI for launch. NASA decided to wait until the X43 investigation was over. This caused HESSI's launch to be delayed indeffinatly while at leist 6 spacecraft launch this summer (NASA refuses to work them back in). This is a problem. HESSI is designed to study the solar maximum, which has practically been missed, and it will fail its mission parameters if not launched by September 2001. This is NASA's fault, not the HESSI team. The HESSI team has done everything possible to get this bird in space, it just hasn't happened. Pull and hope that this bird flies (After the JPL accident, I worked on calibrating the Roll Angle Sensor (RAS) for the star-tracker navigation telescope on board).
  • Basically so that we can figure out were everything came from, where it is and where it's going in a manner that does not require an invisible man whom created everything and thus knows where everything came from, where it is and where it's going.

    That's why.

    While this has been the admirable goal of most modern science, the flaw with it was indicated way back in the Middle Ages (by philosophers who, I might add, came very close to atheism in their suggestions and were ultimately denounced by the clergy, in most cases). Science cannot disprove revelation by proving the eternality and non-Created nature of the universe.

    There are those who say that this "invisible man" spoke to them, and that He said that the world did not always exist. Thus, the assertion of these men with whom you would have science dispute is that we cannot apply knowledge of the present to some arbitrary point in the past in order to determine its condition: the laws by which science 'predicts' past events were not in operation at the time in which these past events supposedly occurred.

    The attempt to disprove this assertion through scientifically establishing the eternality of the universe must therefore beg the question (in the proper use of the phrase). Science attempts to prove that, if we apply the laws of physics to what we observe in the present, we come up with a different story from the one contained in the Scriptures of those men who claim to have spoken with this "invisible man". Yet this is only a valid arguement if these laws describe that past event which we are trying to ascertain: in order to discover what a previous state was from the current state from which it evolved, by examining the law which dictated such evolution, we must assume/assert/prove/[insert acceptable verb here] that this law held during the period of this evolution. But this is precisely the assumption/assertion/[verbal noun] which these men who claim to have spoken with the "invisible man" challenge! Somehow, a proof of this statement would be required. Yet how can one prove this statement without assuming it (aside from having actually been there and possessing a trustworthy memory)?

    The above is a rather detailed way of explaining that Science, in attempting to disprove God by disproving Creation, must assume the fallacy of the very thing which it is challenging. In order to say what the universe was like seven thousand, let alone some odd billion, years ago, Science must assume that the laws (gained from observation of the present) which would allow for such 'prediction' of the past actually operated at that point in the past. The advocates of this "invisibile man" say that such is not the case; Science cannot disprove them by relying on its own bases, viz. that such is the case.

    Since I've spoken of Creation vs. Eternality, I ought to add a paragraph on the Big Bang. Big Bang theories, despite describing the coming-into-being of the universe, are in essence an arguement for the eternality of the universe. Specifically, they say that the laws which governed the Beginning should, in theory, be examinable today: we are bound by our ability to reproduce the conditions of the early universe, but were we able to do so, we would observe similar results. That is, the law which describes such conditions is eternal, if the effect which it produces (viz., us) is not. I have not looked enough into theories which say the 'Big Bang' was the result of a colliding parallel universe to say that they, too, describe the universe in this manner, but I would be very surprised if this were not the case.

    The above argument on behalf of theists is similar to Carl Sagan's dumned-down analogy of the fire-breathing dragon with whom we cannot interact (and thus cannot measure scientifically): who cares if such a Being exists! But as the believers in this Dragon say that He occasionally sets the garage on fire, we must take the challenge seriously. And while we may, on the basis of our own experience, choose to ignore the "Warning: Dragon Here" signs, we cannot prove, scientifically, that the Dragon is not there, no matter how far into the past we extrapolate the laws which appear to govern the present.

  • Your point, which is....?
    SEX!s.e.x.Sex.53X!sex.Si-Ee-Eks
  • No, you forget that we are talking about the universe, you won't find any removable or essential singularities.

    Let's take a look, the only candidate for a singularity is the centre of a black hole.
    Since the amount of gravity is monotonically increasing as you approach the singularity, the point must be a pole.

    So saying it is a pole was in fact quite accurate.

  • The puzzle was posted on Saturday June 30, @12:02PM EDT (#21)

    You can't even wait three hours.
    Why don't you try giving a not obvious solution to the problem.

    Let me rephrase it: Supposing that the universe was hyperbolic (ore spherical for that matter) is the sum of the angles of a triangle drawn on paper 180?

  • The problem with the whole Fire Dragon argument is that you don't add new particles to a theory unless they have some explanitory value. Which in turn necessitates that they have a measurable effect. So whilst a hypothetical being cannot be disproven to exist its existence is of no concequence to science, and while people may claim that he sets garages on fire, it us up to them to provide the evidence for such.

    All this of course has little to do with the Big Bang and such, as you say, the laws that govern the universe today were not necessarily in operation in the past. The problem with this is that it is quite far fetched and there is little reason to suppose that the laws of physics change. (Or if they do change, that they change in some ungoverned manner.)

    Nonetheless, interesting post.
    Reminds me of when the Time Faith BB was up. I wonder, anyone here from there? Probably not.

  • The problem with the whole Fire Dragon argument is that you don't add new particles to a theory unless they have some explanitory value. Which in turn necessitates that they have a measurable effect. So whilst a hypothetical being cannot be disproven to exist its existence is of no concequence to science, and while people may claim that he sets garages on fire, it us up to them to provide the evidence for such.

    This is true: a science which takes its bearing from positivism (in its research methods, if not in its metaphysical statements) would not be extremely interested in variables which it cannot reliably measure. The original post [slashdot.org], however, was attempting to take the positivist statements of science as metaphysical certainty. While we may reliably make statements about what will happen to a ball if I drop it (viz., it will drop), rhinoplastiQue was trying to gather enough such evidence that s/he would not feel troubled by tales of non-natural retribution for not confessing his soul, eating pork, eating beef, drinking wine, failing to sacrifice to the Sun God, sacrificing to the Sun God in direct contravention of some other God's commandment, etc. Ani ma'amin b'emuna shlema, I believe with complete faith, that the math is much easier if we say that the moons of Jupiter go around Jupiter, and will even alter my life according to the predictions made by Kepler, rather than to those made by Ptolemy. This should in no way, however, in itself, enbolden me to ignore prohibitions against, say, non-bloodline incest.

  • Ani b'toronto, canada.

    Yes, I'd agree that that original post was off the mark, nonetheless, I prefer to stick to inferences from things I can see in order to build my model of the universe.

    That's well and good, but the question raised by the poster's hopes is how we then act on our model of the universe. If we can have no knowledge of something which we can't see, but which may someday affect us, we might be justified in acting as if it did not exist. I may be shot dead by some mad sniper, but the chances of that happening are so low and so unprecedented, given the life I have led, that I go about my business without much regard to it. On the other hand, if someone tells me in advance that the sniper told him he was going to shoot me, I might take some action; what kind of action would depend on the reliability of my source. The more fantastic the account, the more scrutiny it must come under, but at the same time, it becomes harder to sleep at night.

  • "what kind of action would depend on the reliability of my source"

    And how does one judge reliability?
    In science isn't this the model's ability to predict events correctly?
    Death on the other hand is a one time thing, which makes the whole issue more complicated - the experiment cannot be repeated, and thus the reliability not checked.
    Generally, models whose reliablity cannot be checked (unfalsifiable) are of no value.

  • Death on the other hand is a one time thing, which makes the whole issue more complicated - the experiment cannot be repeated, and thus the reliability not checked.

    Generally, models whose reliablity cannot be checked (unfalsifiable) are of no value.

    Yes, but I am attempting to make a distinction between what we know and how we act. Unfalsifiable theories may be useless if we wish to determine their validity, but we must still act in those cases in which we are ignorant. Now, if we have only the unfalsifiable theory, one which contradicts what we do "know" about the universe, we may be safe in ignoring it, but if the statement is about something of which we have no previous experience, e.g., death or, more generally, the future, I argue that we must have a different method of determining the best course of action.

    This is what I mean by checking the reliability of the source, not experimental reliablity, for in this case there could be none, but the more intuitive reliability based on trustworthiness. Could the source know what he claims to know? If he knew, would he tell the truth about it? How can I answer either of these questions? etc.

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