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random question

PostPosted: Tue Jun 05, 2007 8:04 pm
by gwendle
How do you pronounce Milndavie?

Is it the same way as you pronounce Milngavie or is it pronounced Miln-davie?

:oops:

PostPosted: Tue Jun 05, 2007 8:53 pm
by dougie79
Hi mate

Just been asking my dad about this and he thinks it should be said as Miln-davie. Dont quote me on this but it may be said that way. My dad thinks best way to find out is to ask the local council, then again do you trust anything a local council tells you? ;-)

Re: random question

PostPosted: Tue Jun 08, 2010 5:14 pm
by Doorstop
Thread resurrection time. For purely selfish purposes as I don't know the answer to the 'Milndavie question and I've a question of my own ..

A serious one.

I've been watching a fair few astronomy documentaries on the "Dinosaurs and Hitler" section of Sky telly of late and I've been struck by a thought (I know, I know .. "was it lonely?", "did it hurt?", "I've often wondered how things germinate in a desert." etc etc etc .. heard them all before and you can't hurt my rotten feelings).


For some reason there are loads of programmes about stellar formations and the life cycle of stars, their birth, chemistry, gravitational effects, evolution, death of etc and it's become apparent that stars are formed from the coalescence of gases (predominately hydrogen) under gravity, right?

The gases collapse in until the density of hydrogen is such that the resulting heat and pressure forces the hydrogen atoms at the core together so tightly (ie the hydrogen hits a critical mass) that nuclear forces are overcome and two hydrogen atoms fuse together resulting in the formation of a helium atom and a burst of energy.

This in turn causes a cascade reaction in which the star ignites and the resulting shock wave blows away most of the material formed during accretion leaving the burning nuclear reaction at the centre which is the resulting star.

So far, so good.

My question is, given that if hydrogen is elemental and is therefore the same density throughout the universe and the critical mass required for hydrogen to fuse in the core of a protostar is a universal constant, why are stars formed in different sizes?

What I'm trying to say is if it takes a certain amount of hydrogen at a certain density/temperature/pressure to ignite and form the star proper how does a larger amount of hydrogen coalesce to form a larger star without igniting first at a smaller size when it hits critical mass?

Hmm?

Re: random question

PostPosted: Tue Jun 08, 2010 5:24 pm
by Lone Groover
Fuckin' Capricorns. I've shit 'em !

Re: random question

PostPosted: Tue Jun 08, 2010 5:28 pm
by Doorstop
That made me laugh .. and I don't know why. ::):

Re: random question

PostPosted: Tue Jun 08, 2010 5:34 pm
by Doorstop
Oh and I've just realised this question is in completely the wrong section and it should be in the Random Distractions slot.

Wasn't paying proper attention during my search Mods, sorry. :oops:

Re: random question

PostPosted: Tue Jun 08, 2010 5:35 pm
by Lone Groover
Sorry mate,it's my spelling. I meant 'acorns'.

Re: random question

PostPosted: Tue Jun 08, 2010 6:15 pm
by Boxer6
Lone Groover wrote:Sorry mate,it's my spelling. I meant 'acorns'.


Am I allowed to invoice for a new keyboard? I just spat coffee over mine when I read that!!! :cry:
:D

Re: random question

PostPosted: Tue Jun 08, 2010 8:01 pm
by BrigitDoon
Doorstop wrote:...the same density throughout the universe...

Is it? What of other substances contributing to the gravitational collapse? If there's a significant quantity of, say, helium, would this produce a lesser amount of energy in fusion and so allow a larger mass to accumulate before igniting?

I don't know what the answer is, I'm afraid, but I'd like to find out.

Re: random question

PostPosted: Tue Jun 08, 2010 8:33 pm
by Doorstop
Perhaps density was the wrong choice of words .. what I probably meant was atomic structure.

Hydrogen has to have the same atomic weight/structure wherever it occurs .. if the internal atomic structure is different then it's a different element right?

As for the presence of helium in the initiatial mix of gases, I'm not certain if that makes a difference given that, while helium is certainly produced in the fusion process, it's inert and unreactive in the initial ignition process of the protostar, hydrogen is the fuel and heat and pressure under gravity are the only catalysts.

Helium only begins fusing itself into heavier elements further on in the star's development as the core temperature heats up as the cascade reaction increases and injects more energy into the fermement.

I don't know why this is bothering me so much but every time I watch a programme on Astronomy etc I spend far too much time thinking about the why's of the whole scenario.

Re: random question

PostPosted: Tue Jun 08, 2010 10:43 pm
by draugelis
Where's Patrick Moore when you need him? He's bound to be an HG'er and I'm convinced he could tell us how to pronounce "Milndavie"!

Re: random question

PostPosted: Wed Jun 09, 2010 1:19 am
by Lucky Poet
Dunno about the Milndavie question, but I like to think the answer to the astronomy question sits somewhere between 'the hydrogen was never uniformly distributed to begin with', and 'it felt like it, cos the universe is some perverse and colossal practical joke'.

Re: random question

PostPosted: Wed Jun 09, 2010 6:34 am
by Doorstop
::):

The first one I've already mentally explored, funnily enough. :roll: I'm a sad act and no mistake.

Where it is indeed true that the distribution of hydrogen throughout the universe is thought to be asymmetrical this, in itself, doesn't make a difference as to the mass required to hit 'critical mass' (that is a constant and a function of atomic weight, nuclear force, weak and strong electromagnetic nuclear forces and Boyle's law).

If the propagation of hydrogen is discrepant, that would only make a difference as to how long the required mass of hydrogen took to reach critical levels - not the amount required to do so.

I really need a hobby.

Re: random question

PostPosted: Wed Jun 09, 2010 6:46 am
by Josef
The Wikipedia explanation sounds as clear as these things can do.

Re: random question

PostPosted: Wed Jun 09, 2010 3:07 pm
by Bridie
Tell you what Doorstop I'll have a stab at this question if you have a stab at mine on the other thread ie How did Sir Branson meet Lady Branson? ::):