Technology Is Time Travel (going backwards) Possible? - Page 19





  1. #181
    Registered User
    Spellbinder (Lvl 16)



    Join Date
    Nov 2002
    Posts
    5,092
    Reviews
    Read 0 Reviews
    Blog Entries
    39

    Ignore Janx
    Quote Originally Posted by KarinsDad View Post
    No, but they are representations of what is being taught to grad students, the statement of yours which I was responding to.
    Are you basically debating about the nature of the ACTUAL content being taught to college physics students?

    In that you think it presents a biased view favoring Dark Matter?

    I have no doubt that any college professor is going to promote his favorite theory over others, as college profs are prone to be quite verbose when going over their primary field of expertise.

    So yes, it is possible that some professors are going to hammer on Dark Matter = real, especially if that's what they own published works favor.

    But I'd also be wary against saying science professors are close minded and teach close mindedness to their students. While they can be guilty of some myopic hypocrisy, as a general rule, the sciences are known to produce people with more open mindedness than any other demographic of humans on the planet.

    that's hyperbole on my part, but there ain't any other degrees that teach a methodology for testing your own ideas (the scientific method).

    I have no doubt you can find video lectures that prove your point. Just as Umbran could fiind video lectures that are more open minded. I think a better test would be to audit a bunch of physics courses at top univerities. that's where the top new physicists are being made, and that's where they are or are not getting brainwashed.

 

  • #182
    Member SILVER DEFENDER
    Waghalter (Lvl 7)

    freyar's Avatar

    Join Date
    May 2006
    Location
    Winnipeg, MB, Canada
    Posts
    18,198
    Reviews
    Read 0 Reviews
    I Defended The Walls!

    Ignore freyar
    Quoting away, sometimes out of order....

    First, about detection of dark matter:
    Quote Originally Posted by Umbran View Post
    Well, some of the suggestions have ways to interact other than gravity. WIMPs, for example, also interact through the Weak nuclear force - and with a large enough detector, you might catch them through such interactions.
    Absolutely! Although, to be honest, people use WIMP to mean anything with a weak-strength interaction, not just the weak nuclear force any more. And these interactions with the Standard Model are reasonably well-motivated. But that part has always been a bit of a guess; maybe there's a whole dark sector with weak-strength interactions and even weaker interaction with the Standard Model. Or DM might interact relatively strongly with the Standard Model but not with the detectors we've built for some reason (yes, I can give some good ones if you want to know). My point is that, while experiments are currently excluding a very interesting part of parameter space, interactions with the Standard Model are not at all required for cosmological dark matter to work. In any case, this is a very very active area because there are a number of hints that we may actually be starting to see some signs of dark matter.

    Quote Originally Posted by KarinsDad View Post
    Or one could catch something else and because the interaction is so weak, one could assume it was what they were looking for as opposed to what it really is. It's an extremely hard science at this point.
    Yes, it is, and the claims of possible detections, some of them very strong, face even stronger scepticism. People know how hard it is and that there are a lot of pitfalls. We're talking about extremely small signals, and miniscule amounts of radiation, etc, cause problems. No one knows this better than the people running the experiments. The results are subject to A LOT of scrutiny.

    Quote Originally Posted by KarinsDad View Post
    How about the Cuspy Halo problem? CDM is the simplest explanation for DM, but the theoretical solutions to this problem require at least some type of an adjustment to CDM models. MOND doesn't have the Cuspy Halo problem TMK because it's a direct outcome of CDM. Pilipenko, Lukash, et al just released a new model a few months back that might solve the problem, but that doesn't mean that the problem is definitively solved yet, correct?
    Problem, what problem? Kidding, kidding...

    Let me explain this for our other readers before I respond, since it's clear you've read a lot about dark matter. I should also mention that the wikipedia page on it isn't very good in that it relies on just a few authors (including at least one who is a noted MOND proponent) and doesn't really get at the consensus. The issue is that simulations of the formation of galaxies using plain vanilla dark matter (and other standard assumptions) suggest that dark matter becomes extremely concentrated at the center of galaxies. This is called a cusp. However, observations of some galaxies suggest that there is no cusp, rather that the density tops out at some maximum value. This is the origin of the "cuspy halo problem."

    Here's the issue with the problem. First, it's tricky to do observations of dark matter halos (since, you know, dark matter is invisible), and, while people agree that there is no evidence yet of cusps, most observers don't think the observations are good enough to say there is evidence against cusps yet. At least not in all types of galaxies -- small galaxies called dwarfs are typically accepted not to have cusps. But the observational situation for big galaxies, like ours, is far from clear, and there could, in fact, be strong cusps still. On the other side of the coin is that the idea of cuspiness comes from simulations which take millions of CPU hours but do not yet include all the physics. In particular, it's only recently that simulations have started to go beyond just the gravity of dark matter and to add normal matter, which does things like make stars, cool down, etc. This can have different effects on dark matter, which might end up making the dark matter more or less cuspy, depending on exactly what happens. It hasn't been worked out well enough yet.


    Quote Originally Posted by KarinsDad View Post
    There are lots of online video classroom lectures and other presentations on the Internet these days. Obviously, nobody is up to speed on everything being discussed, but then again, it's not a complete vacuum either.
    Quote Originally Posted by Umbran View Post
    But those video lectures are not representative of the experience of being a grad student in physics, or any of the hard sciences. You were questioning how actual practitioners thought, and go about their business - video lectures don't show you what and how we actually learn, or how we are taught the activity of doing science.
    Quote Originally Posted by KarinsDad View Post
    No, but they are representations of what is being taught to grad students, the statement of yours which I was responding to.
    I have to go do some work now, so just briefly: compared to the number of graduate programs in the world, there are very very few graduate course lectures available on-line, and only a percentage of those would relate to dark matter or anything similar. Also, the most important part of graduate education doesn't take place in the classroom but in meetings with supervisors and on your own reading, doing homework, or doing research (yes, grad students are important researchers). What that means is that, while even cutting-edge subjects might be presented in a "here it is" kind of way in some lectures, the evidence is also presented, analyzed, and critiqued. That's part of what you learn to do, hopefully even before grad school.

  • #183
    Registered User
    Lama (Lvl 13)



    Join Date
    Jan 2002
    Location
    New Jersey
    Posts
    11,547
    Reviews
    Read 0 Reviews

    Ignore KarinsDad
    Quote Originally Posted by Janx View Post
    Are you basically debating about the nature of the ACTUAL content being taught to college physics students?
    Not so much the content. Go watch that video I posted above and it appeared that the research students were a bit surprised and even a bit argumentative about what Martinus Veltman was saying. Additionally, George Smoot acknowledged the fact that students believe what they are taught in the video ("Because what your professors taught you, you think that is the true science.") as did Veltman ("they are absolutely convinced, and because that's something that they got taught in their early period"). From the videos I've seen online (and granted, that's a very tiny subset of class and lecture material), I haven't seen much push back by students questioning what they are taught.

    My daughter and I have discussed this on many occasions. It's not a matter of merely learning the ideas and theories, especially in theoretical areas, it's a matter of learning where these ideas come from and also on how to evaluate these ideas (i.e. learn how to think). I try to influence her strongly to not only keep an open mind on what she is taught, but find out the reasons behind what she is being taught (who discovered it, how it came about, what competing theories existed, etc.). Being open minded is a bit of a nebulous concept at best, but one that I feel is essential to scientists (considering that she is currently planning to become one).

    Quote Originally Posted by Janx View Post
    In that you think it presents a biased view favoring Dark Matter?
    Somewhat.

    Quote Originally Posted by Janx View Post
    While they can be guilty of some myopic hypocrisy, as a general rule, the sciences are known to produce people with more open mindedness than any other demographic of humans on the planet.
    You have any evidence to support this claim?

    I see lines of strongly opinionated scientists from many different branches of science on both sides of the global warming topic. If the evidence for mankind's influence on it is even somewhat substantial, how come so many scientists from unrelated branches are declaring a side? There either should only be one side that most of them line up on, or these scientists should say that we don't yet have enough data.

    Instead, strong opinions, to the point that they are made public, are formed.

    I could conjecture that mathematicians might have more open mindedness than any other demographic of humans on the planet. Course, I would probably be wrong.

    Quote Originally Posted by Janx View Post
    I think a better test would be to audit a bunch of physics courses at top univerities. that's where the top new physicists are being made, and that's where they are or are not getting brainwashed.
    Actually, Stanford has several grad school level lectures online. There are also free classes online from a few top universities. A guy I work with sometimes takes these and I have been considering the idea.
    The first sign of a broken rule is when someone suggests that the way to stop it is by readying an action.

  • #184
    A problem in the original discussion space (time travel) is that we really are asking the wrong question first: Not, is time travel possible, but, what would it look like it was possible? That is, at a fine, measurable, level, what would we see if time travel were actually happening?

    Why this is important is because folks are talking about the possibility of time travel without figuring out the basic consequences.

    As an example, there is an interesting device in Baxter's Time Ships. I don't remember what they called it in the book, so I'll just call it Plattnerite Pool. What you have is a pool table fitted with time machines in the pockets. A ball dropped into a pocket travels back in time a few seconds or perhaps a minute, then is spat out of a different pocket.

    If time travel of a form allowing travel to one's own past is possible, then Plattnerite Pool is possible, at least from a particle interaction point of view, if not as an actual pool table.

    If such a device were available, and one had a chance to play with it for a while, the question arises as to what would be the stable behavior of the table? A globally consistent behavior must arise as a fixed point from the physics and one's interaction with the device. What possible behavior is there?

    As an example: A ball is placed on the table near one corner. Waiting for a minute or so, a ball appears on the far side of the table, rolls forward to display the first ball, then slowing to take the first ball's place. The first ball rolls into a pocket and disappears with a flash.

    Upon examination, the second ball is seen to be identical, in all ways, to the first ball, except having two very slight smudges where the ball structk itself.

    This example would perhaps be impossible: There is a causal loop with no initial cause.

    As a second example, one decides to do the simplest experiment, and push a ball into a pocket. One approaches the table, watches satisfyingly as a ball appears out of one of the pockets at the predicted time, then deposits the ball (in hand) into a pocket.

    As a third example, one is clever and decides to mix up the experiment. Pocket A goes to Pocket C while Pocket B goes to pocket D. One decides to drop a ball into pocket A if the ball is seen to appear in pocket D, and to drop a ball into pocket B if the ball is seen to appear in pocket C. What happens? Does a ball ever appear?

    Thx!

    TomB

  • #185
    No.

  • #186
    Mod Squad
    Orcus on an Off-Day (Lvl 22)

    Umbran's Avatar

    Join Date
    Jan 2002
    Location
    Boston, MA
    Posts
    27,128
    Reviews
    Read 0 Reviews
    Blog Entries
    6

    Ignore Umbran
    Quote Originally Posted by tomBitonti View Post
    If such a device were available, and one had a chance to play with it for a while, the question arises as to what would be the stable behavior of the table? A globally consistent behavior must arise as a fixed point from the physics and one's interaction with the device. What possible behavior is there?
    That there *must* be a consistent behavior is an assumption. It may well be that no consistent behavior is strictly required. Of course, if it isn't required, one can quickly come up with scenarios where perpetual motion machines and other previously impossible situations become possible.

    It is imaginable that we live in a universe where time travel is not strictly prohibited, but that it can be used in such ways that actually destroy the cosmos.

  • #187
    Registered User
    Thaumaturgist (Lvl 9)

    Nellisir's Avatar

    Join Date
    Jan 2002
    Location
    Ithaca, NY
    Posts
    3,929
    Reviews
    Read 0 Reviews
    Blog Entries
    7

    Ignore Nellisir
    Quote Originally Posted by freyar View Post
    Also, the most important part of graduate education doesn't take place in the classroom but in meetings with supervisors and on your own reading, doing homework, or doing research
    I can testify that no amount of sitting in your room, watching internet videos about landscape architecture, is going to give you the experience of sitting here in studio at 2am in the morning for the third night straight beating your project into shape for a 9am presentation. Along with half your class.
    Secrets of the Shadowend - Notes, scribblings, writings, and memorandum on the Shadowend Campaign Setting.

  • #188
    Quote Originally Posted by Jhaelen View Post
    Why do you think so? What evidence do you have that there's actually more than one possible future?

    Hopefully you aren't under the delusion that you have something like 'free will' and would therefore be able to influence the future in any way
    Time is often seen as a river, a single flowing length of something.
    Many like to believe it has many possible branches and roots and pathways and there are many different 'times'


    But really, time is like a big ball of wibbly-wobbly stuff.
    SO EIN MIST!

  • #189
    Registered User
    Thaumaturgist (Lvl 9)

    Nellisir's Avatar

    Join Date
    Jan 2002
    Location
    Ithaca, NY
    Posts
    3,929
    Reviews
    Read 0 Reviews
    Blog Entries
    7

    Ignore Nellisir
    Quote Originally Posted by KarinsDad View Post
    I haven't seen much push back by students questioning what they are taught.
    I can guarantee that much, much, much more of this "pushback" occurs off-camera. A lecturing instructor has a written plan of the material they want to cover in the 90 minutes they have available. They usually answer questions that are on topic, but it's not a 90-minute free-for-all about whatever theory you feel like bringing up today. There is always a small crowd around the instructor afterwards with students seeking clarification, answers, commentary, and an excuse for missing the last class. Free-for-alls are for office hours.

    Actually, Stanford has several grad school level lectures online. There are also free classes online from a few top universities. A guy I work with sometimes takes these and I have been considering the idea.
    Watching a prerecorded lecture online is to sitting in a real classroom, with a real instructor, as watching online porn is to actually having sex. If that's good enough for you, then so be it, but it's not even close to the same.
    Secrets of the Shadowend - Notes, scribblings, writings, and memorandum on the Shadowend Campaign Setting.

  • #190
    Registered User
    Spellbinder (Lvl 16)



    Join Date
    Nov 2002
    Posts
    5,092
    Reviews
    Read 0 Reviews
    Blog Entries
    39

    Ignore Janx
    Quote Originally Posted by KarinsDad View Post
    Not so much the content. Go watch that video I posted above and it appeared that the research students were a bit surprised and even a bit argumentative about what Martinus Veltman was saying. Additionally, George Smoot acknowledged the fact that students believe what they are taught in the video ("Because what your professors taught you, you think that is the true science.") as did Veltman ("they are absolutely convinced, and because that's something that they got taught in their early period"). From the videos I've seen online (and granted, that's a very tiny subset of class and lecture material), I haven't seen much push back by students questioning what they are taught.
    Bear in mind, when it comes to physics, there's been some discovery that many students, who do great at the math, don't actually understand it, and fail the question on if you drop a 1 pound and 2 pound ball at the same time, which one hits the ground first question.

    They just weren't getting it, and merely parrot or calculate their way through the material, without really grasping it.

    NPR had an article with a physics prof from standford or one of those big schools where he talked about the problem. One of the things he realized was that the way a 20 year physics veteran explains a concept he has undertstood forever to a student is not the same as how a fellow student who just "figured it out" will do so.

    So, he changed up his teaching to present a concept, have the students work out a problem, and then have the students talk and self-correct as the kids who figured it out correctly transmit way of thinking to the rest of the students.

    In any case, I'm still wary that a video of a lecture shows the whole picture on interaction with a professor or even fellow students.


    Quote Originally Posted by KarinsDad View Post
    You have any evidence to support this claim?

    I see lines of strongly opinionated scientists from many different branches of science on both sides of the global warming topic. If the evidence for mankind's influence on it is even somewhat substantial, how come so many scientists from unrelated branches are declaring a side? There either should only be one side that most of them line up on, or these scientists should say that we don't yet have enough data.

    Instead, strong opinions, to the point that they are made public, are formed.
    Of course I don't. I was being hyperbolically exagetative like I said I was.

    There are always scientists who stick to their theory, and belittle other theories. Archaeology has the same problem, when some scientist has proof that the presuumed chain of evolution happened differently due to his new fossil.

    But, the sciences as a whole, tend to produce people who do tend to change their mind.

    As opposed to people who think the world is only 6000 years old. Those people will die holding that belief their entire lives. Since humans as a general rule, tend to NOT be able to change their beliefs, scientists are downright openminded as a subset of the human demographic.

    You can also probably test this by reviewing the public record on each scientist and see if they later change their position on something the rest of the science community disproved. I suspect, you will find that most scientists do shift their position as new information is discovered, though they may cling to certain areas more tenaciously than others.

  • + Log in or register to post
    Page 19 of 24 FirstFirst ... 9101112131415161718192021222324 LastLast

    Similar Threads

    1. Time Travel
      By Gwaihir in forum RPGs & Tabletop Gaming Discussion
      Replies: 30
      Last Post: Saturday, 9th April, 2005, 10:51 PM
    2. time travel
      By jaide_duo in forum RPGs & Tabletop Gaming Discussion
      Replies: 18
      Last Post: Tuesday, 21st September, 2004, 01:23 AM
    3. time travel
      By jaide_duo in forum RPGs & Tabletop Gaming Discussion
      Replies: 4
      Last Post: Friday, 16th July, 2004, 01:53 AM
    4. time travel
      By jaide_duo in forum RPGs & Tabletop Gaming Discussion
      Replies: 2
      Last Post: Thursday, 15th July, 2004, 10:49 PM
    5. Time Travel..
      By Bodah in forum RPGs & Tabletop Gaming Discussion
      Replies: 23
      Last Post: Thursday, 11th December, 2003, 04:08 PM

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •