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Thread: Suggestion thread for new shows

  1. #31
    Join Date
    Jan 2007
    Quote Originally Posted by Tzarkoth View Post
    Firstly, thankyou for providing an excellent podcast.

    I have a topic suggestion or two.

    We have a lot of theories floating around, and far fewer laws. My suggestion for a show would be, when does a theory become a law, and why has The Theory of Relativity not become a law. It appears to be the basis for much of the 20-21st Centuries Astronomy ... and yet its not a law. Is there really a chance that it could be proved wrong?

    My other suggestion, is if we live in an infinate universe, how can we say that the Universe is expanding ... Universe = Infinity+1 ? How can we talk about the Edge of the Universe if its infinite. If its Infinite, wouldn't Dark Energy/Dark Matter just be all that stuff out beyond what we can see/detect distance wise.

    the expansion is happening between the matter and objects in the universe. The space between objects and bodies is growing, and will never run out of room to grow, if the universe itself is truly infinite(or even finite in the case of a universe with no boundary or edge)

  2. #32
    Join Date
    Jan 2007
    Quote Originally Posted by suitti View Post
    We've all heard that in 1998 it was announced that astronomers have evidence that the expansion of the Universe is accellerating. An unknown phenomenon, called dark energy has been proposed.

    If nothing moves faster than light, and that includes gravity, and if the farthest bits of the Universe that are detectable are so red shifted that they are approaching the speed of light relative to us, then could it be that there is simply less stuff in the Universe that can mutually attract? This idea is that we have the same kinetic energy of expansion from the Big Ban, but over time, less and less visible mass to pull it all back together. Or, would this effect work in reverse - since this mass is acting on us from all directions, would having less of it over time act to slow the expansion?
    The furthest parts of the universe are not yet so redshifted that they appear to be approaching the speed of light...I thought of a similiar scenario myself involving dark energy(which is accelerating the expansion....not slowing it down) in which the largest possible size of the universe could be calculated by getting a few accurate distance measurements to distant galaxies, calculating the redshift proportional to the distance, and then calculating how far you could look until the dark energy is not strong enough to accelerate the mass any further(approaching speed C), and the matter density reaches a maximum (approaching infinity). This in effect would make the universe be shaped as a sphere with its center localized in the observers center of mass(that's you, wherever you move). This effect would NOT however, limit the amount of stuff in the universe no matter where you go because the stuff on the edges would move closer to you as you move "toward" the edge, and the stuff behind you would ride around the edge till it was in front of you. Unfortunately the lack of accurate distance measuring capabilities we now have limit this calculation's accuracy, and i'm no mathematician.....

  3. #33
    Join Date
    Jan 2007


    Hi Fraser and Pamela

    Great show. Very much appreciated.: dance:

    My suggested topic concerns the shape of the Universe. Does it make sense to talk about the shape of the Universe? Is it open or closed? Is it a sphere; a doughnut; a saddle shape or some more complex topological construct? Does space go on forever? If one travelled far enough would you eventually return to your starting point? How can astronomy help determine the shape of the Universe. What role does the cosmic microwave background al la COBE and WMAP have to play in such explanations?
    Last edited by Starfighter; 2007-Jan-05 at 01:44 PM.

  4. #34
    Join Date
    Jan 2007
    Thanks very much for these podcasts, which are very enjoyable and absolutely fascinating. You are very good at putting across difficult concepts (or difficult to me, at least!)

    I'd be interested to hear you discuss the prospects for finding life in the solar system, for example Europa seems very interesting and the cancellation of JIMO is depressing, and do the discoveries of water flowing however briefly on Mars suggest that there is life there? What should be our next steps in looking for life in the Solar System, or for intelligent life out beyond?

    Additional point: is Fermi's Paradox the last word on intelligent life elsewhere in the galaxy? Or does it tell us that interstellar travel is impossible because one of the several obstacles is insuperable?
    Last edited by Boromark; 2007-Jan-07 at 04:38 PM. Reason: Adding additonal point

  5. #35
    Join Date
    Feb 2007

    Spheres, Disks, Rotation and Gravity

    I would enjoy a program on recurring structures in the universe with explanations and theories on their existance. Specifically, it's apparent that spherical and disk-like structures occur commonly in the universe at widely ranging scale. For example, the Earth, Moon, and Sun are basically spherical, but the solar system, spiral galaxies, and black hole accretion disks are disk-shaped. Planets such as Saturn have rings that are disks, and systems of moons that describe an ecliptic plane which is roughly disk-like.

    I've assumed that spherical structures get that way because of gravity, and that disk-shaped structures form as the result of rotation of masses around a center-of-gravity. From the descriptions I've read, the accretion disks around black holes appear to be (structurally) the "flattest" disks dimensionally yet observed. Since the ideal disk is described in two-dimensions, and a sphere a three-dimensional structure, it seems that there is a dimensional aspect to mass, gravity, and rotation.

    Here are some questions I would like Pamela to take on in such a program:

    • Do systems of galaxies (such as the local group) rotate? If so, does this impart a disk-like structure to the group?
    • One of the amazing features in the Hubble Deep Field to me is that the planar orientations of the spiral galaxies in the picture appear random. Statistically, is there a "preferred orientation", or are their orientations effectively random.
    • Is the Universe rotating?

  6. #36
    I agree with nova.

    What are the technical differences and different ways they can come to play.

    Like a type 1a vs a supernova. Star going to nova vs going to white dwarf or getting a second chance? and going type 1a? after getting an chance at an accretion disk of material from companion. VS. a type II.

    That little area there was (and still is kinda) the confusing part for me.

    Star skipping nova and going straight to black hole? I read that somewhere too.
    Science magazine maybe. Can't afford NATURE so I know it was not that one.


    The Cheap astronomy guy. What do you expect. Had some time on my hands today.



    That precision adjust gadget from orion telescope for binoculars and spotting scope is way cool and fairly cheap. A little heavy though. But help's alot.

  7. #37
    Join Date
    Dec 2006
    Hi Frazer and Dr Gay,

    Thank you very much for the variable star episode you made my day for sure. While the Seti type cosmology episodes are interesting to me, I actually have some more fundemental questions about Current astronomcal theories and where we might find the answers.

    Next week the NASA "New Horizons" Probe will be experiencing closest encounter with Jupiter. This is interesting to me for two reasons. A.) My understanding is that the plan is to use Jupiters massive gravity to sling the probe toward Pluto, Charon and the Kuiper belt. This in itself might be interestint to discuss... i.e Keplers laws, Newton mechanics and applied balistics. I understand the jest of this but Pamela has a talent for clarifying things. B.) What do we currently know about Pluto and Kuiper Belt Objects and what do we expect to learn when the Probe reaches the edge of the solar system in about 8 years?

    Thanks Larry

  8. #38
    Join Date
    Aug 2006
    How about a Episode on Quantum Mechanics.

  9. #39
    Join Date
    Jun 2005
    OK, so the stars in globular clusters tend to have a chemical signature in common. That suggests that the stars all formed from the same stuff - a molecular cloud. And, they move as a unit because they have the original momentum of that cloud. Some globular clusters orbit our galaxy in orbits other than in the plane of the galaxy. Does that imply that there are molecular clouds that do this also? If not, where did these globulars come from?

  10. #40
    Join Date
    Jun 2005
    <i>So we are told that radio and visible light are the same phenomenon. </i>

    I really have a pretty good idea how radio and light work. To me, it is a interesting topic for a show, because the evidence is, at first, contradictory. So, the answers can be formed into a cohesive story. Many amateurs want to look at neat stuff in scopes. Others want to take pretty pictures. But real astronomy courses talk about rainbows and glories and sun pillars, and northern lights and green flash. I used to think of these as terrestial optical phenomenon, having little to astronomy. But, if you don't understand how photons behave, how are you supposed to know what you're looking at? For example, rainbows work, partly, because the water droplets act as retroreflectors. So, zodiacal light can be understood as a related phenomenon. So, if you get a center brightening during a full moon, it isn't a complete surprise.

  11. #41
    Join Date
    Jun 2005
    <i>The furthest parts of the universe are not yet so redshifted that they appear to be approaching the speed of light...</i>

    Here's how i see it (so to speak). There is observational evidence for z=6 or so red shifted quasars. The cosmic microwave background radiation has a shift of something like 1000 (i've heard 1700). As near as i can tell, that's the red shift edge, or close to it.

    If the Universe is finite in size, then one day we won't be able to detect the CMB anymore. I've no idea if that will tell us how big the Universe was at the moment of the Big Bang. The CMB photons came from somewhere. Since the CMB photons moved in more or less a straight line, and since they move at the speed of light (duh), and since they started their trip to our detectors some 13.7 billion years ago, the Universe was at least that big at that time. As the Universe has been expanding, it must be bigger now. That is, unless there's some sort of wrap around topology. That sort of thing hasn't been detected (that i know of).

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