Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Intro, and a couple of questions

  1. Mar 27, 2010 #1
    Hi guys and gals,

    Stumbled across this forum via google.
    Quick introduction:
    I'm not involved in cosmology at all. But I do have a casual interest in it, simply because it inspires me.
    I'm in my mid 30s, mechanical design engineer, atheist bordering on anti-theist, but that could simply be because I live in South Africa, and religion is a bit more conservative here than the rest of the world I think. I mention my religious view or lack thereof simply because it's primarily responsible for my interest in cosmology. Though that interest now extends beyond that. And indeed my I now have interests in evolution, evolutionary biology, religion, micro biology, science, the scientific method, promoting the understanding of science and a myriad of other relates subjects.

    So I know very little about a lot, which means I really know nothing about everything. And I'm fine with that. The only purpose of it all is to see for myself simply what you guys and girls know, in all the fields I mentioned. A couple of months ago I didn't even know what red shift is. I didn't know about the ERV insertions at the same places of our DNA and all our cousins, right back to each common ancestor.
    I believed all the basics. Evolution, BBT, Gravity. Very basics, that you'll probably consider as below par with what should be common knowledge.

    I read a thread earlier (I lost it now) about critique levied against Lawrence Krauss's talk at AAI 2009 about a the geometry of our universe (A universe from nothing), and I felt compelled to just share a layman's perspective.
    To add a bit of perspective, I'm now approaching 300 video clips (Almost 30gb) Probably around 100hours of actual playing time. On various subjects by various people. Richard Dawkins, Christopher Hitchens, Carl Sagan. And some compilations by proffesionals and amateurs. thunderfoot, tony darnell and so on and so on. And of all these, I value that single talk by Lawrence Krauss most, over everything else. Now I can understand that the universe is actually closed instead of flat, and a quick google shows that Krauss holds this view as well http://arxiv.org/abs/astro-ph/9902189
    But the simplicity with which he explained it all, from virtual particles between the quarks, to quantum fluctuations that could produce a universe, to dark matter and dark energy. Though this doesn't make me physicist and I can't join in discussions with you guys about anything, it is "a" answer for me. Just a broad understanding of what we know/think about the universe. Even if it just points to the direction in which we are thinking. Expansion of spacetime.

    So while everything he said may not be factually true for you guys, it's the only way I can be made to understand more or less with the little understanding of your world, that I have, and the 1 hour he used to convey that.

    And not only does it inspire, it also intrigues me, and pulls me in deeper.
    Which is the other reason I'm here:
    If I combine one of Carl Sagan's clips from the old Cosmos series, the 4th dimension
    with Lawrence Krauss' video, an interesting "beg the question" arises for me. Yes I know, not scientific, but I'm not a scientist, so I can get away with some, and indeed a lot of speculation :-)

    In Carl's video, while the apple is floating above the flat square, the flat square cannot see the apple or interact with it. But, the apple will still have a gravitational influence on the flat square? The square and apple should gravitate to each other? Though the flat square cannot be elevated to the 3rd dimension, it should be pulled in the 2D direction of the floating apple. Or rather experience an attractive force proportional to their mass? As I understand, again, I understand very little, but if I understand some experiments of the LHC correctly, a graviton could be produced. Which I understand as a unit-particle of gravity, or a gravity-particle. I don't even know how to describe it.


    My question is, has the possibility been considered that dark matter and dark energy are simply "matter" with "mass" in the 4th dimension having an influence on objects with mass in our 3 lower dimensions? Higher dimensional matter that cannot be seen or interacted with, but of which we can only see it's influence in our 3 dimensions.

    If this is utter bull, bordering on UFO-conspiracy theories and the super natural, please say so. I have no ego on the matter, just pure curiosity. You have no idea how hard it is for us laymen to find some science in a easily digestible and understandable form out there, that we can squeeze in after dinner and before going to bed. Mainstream media is shoving super natural tv series down our throats, hyped up and suped up science that has entertainment value, more than educational value.

    Thanks for your time, apologies for the wall of text!
    Thanks for the work you guys and gals are doing for us! Really, thank you!
     
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Mar 27, 2010 #2

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    Hello Red,
    you are cordially welcome here. Plus your post raises a lot of issues that could be interesting to discuss.

    I hope others will respond to more of your questions---I'll just address a small facet.
    I admire Larry Krauss a lot. He is a brilliant thoughtful guy and an outstanding communicator.
    A solid scientist and who can double as a science personality.

    I remember watching that talk you mentioned. He oversimplified. I can understand that, and justify it, given the audience. As far as we can tell the spatial geometry is nearly flat. But we don't know exactly what the curvature is. There is an error-bar or interval of uncertainty. The overall largescale curvature (as far as we can tell) might be slightly pos, or zero, or slightly neg.

    For all practical purposes (if that means anything) it is flat---the spatial curvature is zero---and space is quite possibly infinite. But we don't know for sure and from (for instance) my perspective that is probably the most interesting thing. The fact that we don't know.

    But he had only a few minutes to get some general ideas across to an audience where a good portion think verbally, or philosophically, not mathematically, and might not be interested in his being overly precise. So, as I recall, he didn't say "nearly". He just said plain flat. He didn't emphasize the imperfect state of our knowledge. He laid out an oversimplified picture as if it were established fact.

    So that's fine, if you don't want to go any further. It will do OK if you just want a mental picture of how things are and don't want to learn more or ask questions based on it.

    But if you want to go further then you will probably end up unlearning some things he told you.

    I don't have a transcript and I don't want to listen to it again. So I can't quote you chapter and verse.

    So I would suggest a different approach to you. Besides collecting video of essentially inspiring scientific visions of nature and the universe, collect also some LINKS TO READING MATERIAL that you can show to us, and say "what does it mean halfway down page 3 where he says....?"

    If you have ONLINE TEXT then its very quick to see what you are talking about.

    And you already did this in one case where you give link to a Krauss Starkman article from 1999. But you seem to be offering as evidence that Krauss accepts a spatially finite universe. Where in the article does it say that? I just glanced at it and it seemed to me that they were considering a spatially "open" case. You may be right, and perhaps I just didn't dig hard enough to find what you are talking about. Or I misunderstood either you or Krauss. So you could help by being more explicit.
     
  4. Mar 28, 2010 #3
    Thanks for the reply Marcus!
    It almost feel like we're back in the times of the flat earth. And with the instruments and knowledge we have today, it's just as hard to measure a curvature as it was for the ancients to perceive the earth's curvature. Reminds me of a video about a Isaac Asimov essay

    And you are correct about Prof Krauss and the universe geometry. In that paper he did indeed write about an open universe, not closed as I stated. That'll teach me to post at 3am in the morning :-) In the talk he did include an accuracy for the statement that the universe is flat. Better than 1% IIRC. But even a 1% error around curvature means the possibility is very real that the universe could be slightly curved either way from flat.

    I also want to clarify one point a bit. It's not that I don't want to learn more, I just simply don't have the time. And I will learn more as time goes on, but I'll never master mind bending abstract concepts. It will occupy too much time to get my head around these, and the time could be spent on another subject. So, even though I will continue to learn more, as scientists continue to understand more, whatever I learn will always only be at the level presented by Krauss. Put simply, I just want to see what you guys know, I don't need to know what you guys know.
    This is in part why I try to stick to videos as source of info. I can still rest and relax, and it's not as taxing as reading a physics paper that contains terms that I have to consciously translate and interpret, and concepts that have to be visualized from paper. Also papers tend to focus on a very narrow subject at a time, a very small piece of a puzzle. English is also not my first language, but second. though my vocabulary has improved over the last couple of months, especially thanks to Hitchens and Dawkins.
    But I do thank you for the offer! And still will take you guys up on it!

    Have a good day, and enjoy the week!
     
    Last edited by a moderator: Sep 25, 2014
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook