This is the question that I always wanted to ask Carl Sagan, but, unfortunately, he’s not readily available to answer it.
We’ve generally been lead to believe that we’re in a nicely symmetrical, ‘pretty’ galaxy like the Andromeda Galaxy, M31.
I think that this is almost un-knowable, and a massive case of wishful thinking; we want to be pretty, but where’s the basis for saying so?
I’ll accept that we’re near the outer edge of a spiral galaxy, it seems possible to discern this.
Imagine that you’re looking edge-on at a piece of cardboard. This is our situation in the galaxy. Now, what’s the shape of the piece of cardboard? How could you posibly know??
Okay, you can determine the distance to various stars due to red-shift, but I’m not aware that any comprehensive survey has been, or will be done, and it seems doubtful that any definitive result has been obtained to-date.
ISTR that someone said a few years ago that we might be in a barred spiral galaxy, but again, how would they know?
So, just what is the shape of our galaxy, anyway? Is there good evidence for the conclusion?
Hi Amee, welcome aboard (he he he get it, welcome a - board!!.. sigh)
The OP was asking about the shape of our galaxy rather than the whole universe. I thought we had good reason to believe it’s a nice spiral shape, but I don’t have access to any reasons why we do think this.
The quote is “Could Jesus microwave a burrito so hot that he himself could not eat it?” And I think Hawking: “Your theory of a donut-shaped universe is intriguing, Homer. I may have to steal it.” would be equally appropriate here…
but then where do the so-called ‘pictures’ of the Milky Way come from???
anyway i’m inclined to believe it’s spiral. don’t ask me why. in any case, the Milky Way is spinning really really fast so that may explain for the arms coming out from the spiral.
or maybe it has to do with the super-gigantic-massive black holw in the Milky Way’s centre. does it?
