Timeline for Universe Expansion
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 7, 2013 at 11:57 | comment | added | Thriveth | Instead of drawing dots on the balloon, tape coins or something on it. They won't expand as you inflate it - there's your analogy. | |
| Jul 12, 2011 at 4:22 | comment | added | Stuart Robbins | @Warrick: The analogy is imperfect since yes, the dots do expand. The better analogy is the raisin bread one, but that doesn't illustrate quite the same thing (2D expanding in 3D). ghoppe is somewhat incorrect, though. At present, galaxies do NOT expand, as they are held together by gravity which is stronger than the expansion force. Same with clusters. There WILL come a time, though, when gravity is NOT strong enough and galaxies will actually be dragged apart by the expansion of space. Don't remember off-hand what that time-frame is, but it's at least in the billions of years away. | |
| Jul 11, 2011 at 20:32 | comment | added | ghoppe | @Warrick in short, the greater the distance, the greater the rate of expansion. | |
| Jul 11, 2011 at 20:31 | comment | added | ghoppe | @Warrick Yes, in fact, the dots do expand. Even the space between an atom's nucleus and its electron cloud expands. The galaxy (distance between stars) is expanding, too. However if you do the math you'll find the dots won't cover 1/100 at the start and at the end. | |
| Jul 11, 2011 at 7:52 | comment | added | Warrick | Despite hearing it so often, I've never been convinced by the balloon analogy. Don't the dots also expand? If a dot covers 1/100 of the balloon when you draw it, doesn't it still cover 1/100 once you've inflated the balloon? If so, then I feel like the analogy implies that the "galaxy" is expanding too. Of course, maybe I have insufficient experience in inflating balloons... | |
| Jul 8, 2011 at 20:57 | history | answered | Stuart Robbins | CC BY-SA 3.0 |