Expanding space?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by kaneda, Nov 7, 2007.

  1. shalayka Cows are special too. Registered Senior Member

    Messages:
    201
    The one cooked in the microwave tastes like crap. Seriously, do not cook a roast in the microwave. That's nasty.
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Read-Only Valued Senior Member

    Messages:
    10,296
    Yeah, and not only that, it will be grey and unappetizing-looking. Yuck! Unless it has a built-in electrical heating element to brown it.
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. losfomoT Unregistered User Registered Senior Member

    Messages:
    125
    If the planet is rotating, you should be able to detect a coriolis force somehow (I'm not sure what device you might use).


    To be honest, I think he understands perfectly. He just won't admit it, and he likes to argue.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. losfomoT Unregistered User Registered Senior Member

    Messages:
    125
    :thumbsup: Good on you. I should have covered my ass better...I realized that after I posted... yes there are ways to tell if you that you are probably on a planet... but the fact that you have to resort to measuring something unrelated to the acceleration just goes to show you anyway.
     
  8. Read-Only Valued Senior Member

    Messages:
    10,296
    Neither would likely help him. A planet with only 0.1g is not likely to have an atmosphere (there goes his cloud chamber) nor a magnetic core (there goes his compass).
     
  9. superluminal . Registered Senior Member

    Messages:
    10,717
    Ok,

    A non-gravitational acceleration will produce a uniform force across the box, whereas a gravitational acceleration due to a spherical planet will produce a force that deviates from normal (vertical) everywhere but the centerline of the box. It might take an extremely sensitive plum-bob to measure it, but it's there.

    EDIT:

    So I ran the numbers and if your box was a 10m cube then, on the earth, the deflection from vertical over a 10m plum-bob at 5m off the center line would be about 8um. I think a laser measuring device could do this.
     
    Last edited: Jan 5, 2008
  10. superluminal . Registered Senior Member

    Messages:
    10,717
    I really wish there was a simple sketch feature in this forum.
     
  11. losfomoT Unregistered User Registered Senior Member

    Messages:
    125
    Yes, but my praise was in response to his response to my question which specifically mentioned the Earth.

    I am trying to set an example, whereby if one of us admits he is right once in a while, maybe it will rub off on him.
     
  12. superluminal . Registered Senior Member

    Messages:
    10,717
    I've done that a couple of times with him. He has some kind of force field or something...
     
  13. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
    3,181
    Yes, you are correct of course, super. I would think another way to differentiate between uniform acceleration and normal gravitational acceleration is by using a large box, say one several hundred kilometers square. The force measured in an accelerating box will be identical everywhere within the box and the plumb-bob lines will all be vertical, whereas within such a large box sitting on the Earth, one would measure a difference in gravitational potential between the top and bottom of the box, as well as plum-bobs that are seen to converge from the sides.
     
  14. superluminal . Registered Senior Member

    Messages:
    10,717
    Right you are.
     
  15. losfomoT Unregistered User Registered Senior Member

    Messages:
    125
    And in that spirit, I should mention that he already pointed out your answer to the problem as well (...I think that's what he meant, anyway):

     
  16. superluminal . Registered Senior Member

    Messages:
    10,717
    No... I read that and that's not what I took it to mean at all.

    On any scale all of the earth attracts us. What else could this mean?

    And by implication, what???

    I really can't understand this.
     
  17. Read-Only Valued Senior Member

    Messages:
    10,296
    Ah, yes - thank you.

    Please Register or Log in to view the hidden image!

    I had thought of something quite similar but since the conditions, as stated, involved a 10-meter box and and 0.1g (I think), the deviation would be so small I was guessing it would be undetectable.
     
  18. kaneda Actual Cynic Registered Senior Member

    Messages:
    1,334
    I have never used one but I am told that browning dishes work very well.
     
  19. kaneda Actual Cynic Registered Senior Member

    Messages:
    1,334

    Of course I like to argue. Questioning anything is the best way to learn. The air you are breathing would also tell you if you were in a rocket ship since it would not contain the casual impurities Earth's astmosphere does.
     
  20. kaneda Actual Cynic Registered Senior Member

    Messages:
    1,334
    Our Moon has a G force about 0.16G so not a planet if it only has 0.1G. I would think around 0.25G would be the minimum for what we would recognise as a planet?
     
  21. kaneda Actual Cynic Registered Senior Member

    Messages:
    1,334
    You could try scanning one into your computer, putting it on photobucket (or similar) and so putting the image here.
     
  22. kaneda Actual Cynic Registered Senior Member

    Messages:
    1,334
    I've never understood why the effort to try and prove someone wrong rather than just posting what you believe/know to be right. Of course gravity in a room on Earth would be mimicked by being in a spaceship accelerating at 1G, the same as infra-red and microwaves while different can heat something up.
     
  23. superluminal . Registered Senior Member

    Messages:
    10,717
    Uh huh.
     

Share This Page