I have a physics degree from the University of Montana, and I love talking to people about science. Between tutoring and informal education, I love what I do.
@zack-m
Zack M.
commented
@salma a. welcome to Socratic! I double checked your answer, and it looks like it should be '45n' in the second statement. Also, you can reduce your final answer by dividing by 5.
on
How do you simplify #-10n - 5( - 6- 9n )#?
@zack-m
Zack M.
commented
As for your other point, I admit I haven't really thought about expansion that way, and it is intriguing. Do you have any sources that I can check out that include time dilation in the calculated age of the universe? I'm too lazy and rusty to do the math on that one. I did find a couple of links about "proper time." They seem to imply that this time dilation is irrelevant in the calculation, but I am still curious about what happens when it is included.
I do stand by my previous argument, however, about the difference between expanding matter and expanding universe. A more precise statement of your axiom is that "information cannot travel faster than the speed of light." Again, I'm rusty on this subject, and don't think I can do the argument justice, so please check out this link;
@zack-m
Zack M.
commented
As far as the original "central point" argument, my concern is the word central. Central is a relative term, for which there should be an answer to the question, "central to what?" If you simplify the universe to a two dimensional membrane, like the surface of a balloon, then universal expansion becomes analogous to inflating the balloon. Then the universe, the surface of the balloon, can be seen to expand from a central point inside of the balloon. If I understand you correctly, this is the central point that you are referring to. The problem is that this point is outside of the universe and therefore has no physical meaning to the universe. That's where the model breaks down. Even if you run the clock backward to when the balloon is contained within that same point, you can no longer answer the question, central to what. For a slightly more thorough explanation, check out this link: