Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum Upper limit to the Lifetime of the Universe from Anthropic Reasoning

Hi Count:

With all indications being what we are told we will use up all our nine lives before things go elsewhere it is a little difficult to get worked up about it.

The Solar System, I believe, has a shorter life cycle than the Universe and that is of more interest to me. I saw an article once (nameless now) that said, not sugested, that the Sun would eventually go into the enlarged state of a big red ball and incinerate the Earth by growing into our orbit. This enlargement is part of the Sun running out of fuel.

I wrote the source, or somehow contacted the persons, asking why that would happen if the size of the enlargement was due to less fuel wouldn't the Sun lose Mass in the process so that the Earth would have beeen slipping off into space with each instance of the diminished gravitation of the Sun meaning we would be farther away when the Sun went into a red giant.

I never got an answer and the details of the article source, or whatever, are very vauge now.

My question is whether the Solar System would expand as the Sun lost Mass equivelant to the loss of Mass over time? I have guesses only.

Sun turns to red giant.
http://www.space.com/scienceastronomy/solarsystem/death_of_earth_000224.html

Of particular interest is the following paragraph:
"As the sun burns its core of hydrogen, gravity will force a collapse. When compacted, the sun will heat up and burn the small amount of hydrogen that remains in a shell wrapped around the star's core. This will force the sun to expand into a red giant. Eventually, the core will heat up enough to burn stored helium and the sun will fluctuate in size before collapsing into a white dwarf."

I was guessing that as the sun lost mass/energy, it would lose mass, thereby decreasing density, but my guess was wrong.

Check out http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/971016.html
and even better
http://science.howstuffworks.com/sun5.htm

TFF:
Thank you for the links.
Right on target.