100 Billion: The Only Number You Need to Know About the Universe
My students and I have really been enjoying Sean’s Cosmology Course. Today’s lecture tied in the idea of a smooth, expanding universe with general relativity.
This lecture has been my favorite so far, there were a few moments in there where I not only learned some new things, but that sometimes I’ve been trying to hard to convey cosmological concepts that were really pushing the boundaries of what we know or can even visualize (e.g. the size of the universe). I see now that I should take a slightly different tactic in my writing when it comes to certain cosmological ideas.
One of my favorite moments in this particular lecture was this:
Every galaxy has something like 100 billion stars in it. There are something like 100 billion galaxies spread across the universe. The good news is that they are scattered uniformly. There is the same density of galaxies all over the place.
So, if you want to know how many stars there are or how many galaxies, just think 100 billion.
Number of stars in the universe? 100 billion stars/galaxy times 100 billion galaxies. Who said cosmology was hard?
Technorati Tags: cosmic variance, cosmology
100 billion galaxies each with a hundred billion stars. Now take that one step further for us:
How many stars in the universe?
How many planets in the universe?
How many moons in the universe?
How many atoms in the universe?
and lastly, one from my daughter,
How many McDonalds in the universe?
Ok. My daughter’s answer to how many McDonalds in the universe was an easy one. Answer: “Not enough”…
Im not so sure about this…
We cant see far enough to be able to determine how many galaxies there are in the universe, 100 billion may very a very nice safe easy to comprehend number, but I dont think its even remotely close, just two weeks ago a few Australian scientists discovered that the Milky was is in fact twice the size previously thought, using only existing data…
My question is: Why do we need to know about the universe?….because is fascinating, good to know what is out there?… no, one bigger purpose; because people are curious, and wonder to much, and just want to know, and want to go wherever their imagination takes them to?…ok let me think even further; Is it because it will help us in the future? what about now?, the tomorrow depends of the today?….. Well, it looks like my inmagination is taking me far as well. Maybe that’s the answer, just because imagining feels great… now I understand the quote of Einstine…”Imagination is more powerful than knowledge,” somehting like that I guess….
Seriously, this is the ultimate question: Where are we heading?
Suggestion; Instead of asking what something is, is better to ask what something is not…. reason is because, asking what something is, you would get a tone of answers that are not wrong, neither right, but good, great or excellent. Think about it, and instead of What, why, where, when, how….ask yourself what is not.