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Author Topic:   Looking for info on pre-Pangea supercontinents.
Justin W
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Message 1 of 8 (40272)
05-15-2003 2:40 PM


I did some quick browsing of this forum and it looks like a lot of well informed people spend their time here. I especially like the topics in the "Big Bang" forum.
I am doing a Geology project and was wondering if anyone here could point me towards some resources that could explain continent formation leading up to Pangea. Graphics would be great.
I also have a Physics question. In our physics book it says that neutrinos travel freely through mass. The book also says that deuterium(heavy water)absorbs them(or something to that effect) and photons are produced that can be detected to prove the existence of neutrinos. How can this be?
Thanks in Advance.

Replies to this message:
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John
Inactive Member


Message 2 of 8 (40274)
05-15-2003 3:01 PM
Reply to: Message 1 by Justin W
05-15-2003 2:40 PM


quote:
In our physics book it says that neutrinos travel freely through mass. The book also says that deuterium(heavy water)absorbs them(or something to that effect) and photons are produced that can be detected to prove the existence of neutrinos. How can this be?
It isn't that neutrinos never interact with other particles but that they do so very rarely. The vast majority just fly right through pretty much everything-- whole planets--, but the rare one produces a detectable effect.
------------------
No webpage found at provided URL: www.hells-handmaiden.com

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Coragyps
Member (Idle past 755 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 3 of 8 (40278)
05-15-2003 3:20 PM
Reply to: Message 1 by Justin W
05-15-2003 2:40 PM


Try Googling for Rodinia and for Godwana or Godwanaland.
And Welcome aboard!

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roxrkool
Member (Idle past 1009 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 4 of 8 (40286)
05-15-2003 5:11 PM
Reply to: Message 3 by Coragyps
05-15-2003 3:20 PM


Here's a site that I like. It has some cool graphics and animation.
Home Page

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joz
Inactive Member


Message 5 of 8 (40288)
05-15-2003 5:49 PM



NosyNed
Member
Posts: 9003
From: Canada
Joined: 04-04-2003


Message 6 of 8 (40299)
05-15-2003 6:53 PM
Reply to: Message 1 by Justin W
05-15-2003 2:40 PM


Freely through mass
The "freely" isn't a very well defined term is it?
What it is supposed to be saying is that the neutrinos "mostly" pass freely through matter but not quite completely.
There is a measurement called the "cross section". It tells you how likely it is that one particle will "run into another". It is just like it sounds a kinda measure of how big it is. You know the old saying "as big as a barn door". Well that suggests that a barn door has a very large cross section and would be hard to miss.
A neutrino passing through other matter has a very small cross section, very, very, very, very small but not zero. If you fire enough neutrinos throughs a big enough chunk of matter then one neutrino in a few kajillion will actually hit something. (Hit meaning interact with).
from http://zebu.uoregon.edu/~imamura/208/feb3/results.html
"10**10 neutrinos per square centimeter per second at the Earth. "
And with those passing through a giant tank of water 10's of meters on a side you get a few collisions (very few).
So to say they pass "freely" is true but it is not true that they NEVER interact.

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Justin W
Guest


Message 7 of 8 (40753)
05-20-2003 11:34 AM


So the neutrinos are just passing through the part of the atom which doesn't contain the nucleus(which is over 99% I believe)and only rarely does a collision occur. That makes sense.
Thanks for those links, my project is now getting underway.

Replies to this message:
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NosyNed
Member
Posts: 9003
From: Canada
Joined: 04-04-2003


Message 8 of 8 (40768)
05-20-2003 2:22 PM
Reply to: Message 7 by Justin W
05-20-2003 11:34 AM


passing through
..doesn't contain the nucleus
Now we are streching what I know a lot but I don't think that it either. I think it can pass through the nucleus without interacting most of the time. (It probably has to whallop a quark in just the right way).

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