View Full Version : Astrophysics an stuff

tony draper
14th Nov 2002, 12:04
Draper dropped out of chat early last night, wasn't nowt on the telly, so Draper sat and just thunk for a while, Draper used to often do that,but was a tad out of paractice what with spending lotsa time in chat rooms and such.
The universe started with a big bang, OK thats the accepted wisdom.
So from a single point everything flew outward, so it follows that somewhere in our universe is a null point ,
the point everything started from this must be a pretty quiet place now.
At this place, no matter what direction you look all objects at equal distances must be equaly red shifted. there can be no blue shifted objects in the null point sky.
Now Drapes is aware that no matter where you are in our universe things appear to by flying away from you in all directions, the anology of dots painted on the surface of a balloon is often used,to a person sitting on one of those dots, they would appear to be stationary and all the other dots would appear to be moving away from them when the balloon is inflated.
Now the further objects are from your point the faster they appear to be moving, The Hubble constant its called.
So there are Galaxies flying out in more or less the same direction as us, but further ahead and are therefore more red shifted, just as there are Galaxies behind us but traveling in the same direction that should be red shifted to a lesser amount, ie they are actually receading from us because they are behind us.
On the opposit side of the null point from us there must be objected very red shifted because they are receding at their own speed plus our own speed.
So how come nobody has found the universal ground zero?,seems to Drapes it would be a easy excercise.
Just look for th epoint of maximum red sift and in that direction lies big bang central.
Its this poxy speed of light thing that baggers this up.
Ah well, back to chat.

Draper is aware that pilots spend most of their time sitting behind the drivin wheel of their airyplane just lookin out the front window with nothin to do, one just wondered if you chaps ever pondered these deep questions or just thunk about wimmin all the time. ?

Select Zone Five
14th Nov 2002, 12:12
Ouch, my head hurts...:rolleyes:

As well as finding this null point, I'd like to know just exactly what the universe is expanding into? "The Universe" by definition, is everything, is it not? If that is the case, how can it be expanding? Whatever it is expanding into is already part of it!

I need to lie down...

14th Nov 2002, 12:34
Big Bang theory?
Who lit the fuse to make something explode out of nothing? :)

Frankly Drapes, I don`t believe in that at all.
History shows that scientific theories change with evolution of human knowledge.

About thunking of wimmin when flying.

What makes you think so lowly of us? We are serious professionals, Tony. Our job is to transport you safely and comfortably to your destination. If we should be distracted by nice thoughts like that, it would indeed jeopardise the quality of our craftmanship.

In the crew lounge however...
that`s another story. ;)

Anthony Carn
14th Nov 2002, 12:55
I think about all sorts as I stare out the plane's front window.....

I'll try your red-shift, blue shift thingy next time, drapes --
Kylie in a red shift, Britney in a blue shift. I'll think deep, penetrating thoughts. Light emmisions. Things expanding. Where's that null point. Big Bangs. Ring nebulae. Black holes.

It'll make a change from sex.

14th Nov 2002, 13:15
'Tis easy, Tony.
All you have to do is get your head around this - The Big Bang wasn't a bang as such, but more of a rapid expansion of space-time. Because the universe itself was expanding, and the universe contains everything that there can be, there is no central point and so everything is (generally) moving away from everything else.

tony draper
14th Nov 2002, 13:30
Shhhhh Bill!!, Drapes knows this,Drapes was just testin these folks.
Good grief!!! we appear to have Fred Hoyle steady state heretics here.
PS, any prooner with a IQ of 248 or over will spot the flaw in Drapers reasoning, ;)

14th Nov 2002, 13:44
Yer basic balloon priciple is right.

Cover a balloon with dots and inflate. All the dots move away from all the other dots.

But just like all the dots, us humans can only perceive (and walk around on) the surface of the balloon.

Yer can walk all over the balloon (the universe) and visit every dot (star) but yer can't reach the middle of the balloon coz it's out of yer dimensional reach, see?

Konkordski (astrophysics graduate, an' that's the truth :p )

14th Nov 2002, 14:02
Plus, no matter how hard you try, you can't even see it, since the null point (Hey drapes, you going to write a paper on this for Science? :D ) is hidden away behind the heat radiation from the big bang :D

14th Nov 2002, 16:17

So as I can get me muddled, shrinking, aching brain around this problem, please explain what the **** you mean by red and blue shifted.
I have the honour to remain your humble servant

Whiz :cool:

tony draper
14th Nov 2002, 16:35
Well Mr Whiz you must be familiar with thr phenomena of doppler shift. if yer standing still and say a Tornado gr1 is approaching you, the sound changes when it goes past yer ie, ggggggggrrrrrrroooooooh,the oooom bit being when it has gone past,.
The sound waves are compressed as the body, ie, said Tornado approaches then elogated as they pass.
Things are different with light , the speed of light is constant, 180,000 mps not matter how fast the body emitting the light approaches you the speed the light hits you is still 186,000 mps.
This is very strange, wghat does happen though, various absorbtion lines in the spectrum of said light are either shifted toward the blue end of the specrum or the red end of the spectrum depending whether the sourse emmiting the light is approaching or moving away from you.
One can calculate how fast said light emmiting body is receding or advancing toward one by measuring this red or blue shift in the spectrum.


PS this can be a useful bit of knowledge, as this penomena is universal, if for instance you are out walking in the valleys and are confronted by flying saucer, with a alien standing in front of it,(especially those little grey bastards, apparently they are fond of useing a arse probe for some reason,) if you have about your person on of those torches that can shine red, green or blue, shine the red light at the little bastard and no matter where in the universe he /she/ it, hails from they will know this means **** off.

14th Nov 2002, 16:39
Doppler shift Whiz, like the sound of a train whistle as approaches and then passes you. It's shifted up as it approaches and then down as it retreats. Thus if a light source is approaching you, the frequency is shifted up towards the blue end of the spectrum; and if it is retreating, the frequency is shifted downwards towards the red end of the spectrum.

If you can work out the frequency the light should be, as you can for sources such as cepheid variables, you can calculate the speed at which they are approaching/retreating.

14th Nov 2002, 16:47
OK Drapes.

What you've got to do, right - is to imagine you've got a sheet of graph paper, OK ?

And the thing is, this graph paper, right, it's infinitely big, yeah.


OK - so there's an infinite number of squares on the paper. Agreed.

Now. At time t=0 each of those squares is infinitely small, right.

But because there's an infinite number of them the paper is still infinitely big. Got it ?

OK - as time passes the size of each square increases. At some moment, let's say that each square is one millimetre across.

OK - the paper is still infinitely big, right - you've got an infinte number of 1mm squares.

Okay - you can see where I'm going with this now. After twice as much time has passed, each square is 2mm across - after ten times, each square is on centimetre across, and so on.

The size of each square is the scale factor. By now the scale factor is many parsecs per square, but the piece of graph paper is still the same size - it's infinite, remember ?

Now your galaxies, right - they stay put as far as the squares are concerned. Two galaxies that are ten squares apart are always ten squares apart. But as the squares get bigger, the distance between the galaxies increases. Two galaxies that are twenty squares away from each other will move apart twice as fast and so on.

Well, I'm glad that's all cleared up ...

tony draper
14th Nov 2002, 16:48
err Drapes just said that Mr ORAC, not as elegantly one admits, Mr whiz hailed originaly from scotland, is doesn't do to get to technical with one of that race.;)

14th Nov 2002, 16:56

it is a matter of regret that no-one has mentioned a superior entity. how long has it been since any of you went to church?

hello draper.:p

tony draper
14th Nov 2002, 17:00
Ahoy Mr fantom, well met sir,
Indeed the collection plate has sadly thin pickingings now. :(

A brilliant explanation of inflation and expansion Mr Grainger, thank you.
Could perchance you explain super string theory for us, err if you have a minute?? .

14th Nov 2002, 17:43
Pah! Forget string theory Drapes, I wanna see Grainger explain M-Theory :D

14th Nov 2002, 17:50
Not physics but possibly applicable?

The following is an actual question given on a University of Washington engineering mid term. One answer was so "profound" that the Professor shared it with colleagues, which is why we now have the pleasure of enjoying it as well.

Bonus question: Is Hell exothermic (gives off heat) or Endothermic (absorbs heat)?

Most of the students wrote Proofs of their beliefs using Boyle's Law, (gas cools off when it expands and heats up when it is compressed) or some variant. One student, however, wrote the following:

First, we need to know how the mass of Hell is changing in time. So we need to know the rate that souls are moving into Hell and the rate they are leaving. I think that we can safely assume that once a soul gets to Hell, it will not leave. Therefore, no souls are leaving.

As for how many souls are entering Hell, let's look at the different religions that exist in the world today. Some of these religions state that if you are not a member of their religion, you will go to Hell. Since there are more than one of these religions and since people do not belong to more than one religion, we can project that all souls go to Hell.

With birth and death rates as they are, we can expect the number of souls in Hell to increase exponentially. Now, we look at the rate of change of the volume in Hell because Boyle's Law states that in order for the temperature and pressure in Hell to stay the same, the volume of Hell has to expand as souls are added.

This gives two possibilities:

1. If Hell is expanding at a slower rate than the rate at which souls enter Hell, then the temperature and pressure in Hell will increase until all Hell breaks loose.

2. Of course, if Hell is expanding at a rate faster than the increase of souls in Hell, then the temperature and pressure will drop until Hell freezes over.

So which is it?

If we accept the postulate given to me by Teresa Banyan during my Freshman year, "...that it will be a cold day in Hell before I sleep with you.", and take into account the fact that I still have not succeeded in having sexual relations with her, then, #2 cannot be true, and thus I am sure that Hell is exothermic and will not freeze."

This student received the only A.

Anthony Carn
14th Nov 2002, 18:13
To truly understand superstring theory, one would need to be a p-brane. :p

14th Nov 2002, 18:21
*rolls around on floor laughing*
Oh dear :D

15th Nov 2002, 00:12
Sir, I would kindly refer you to Python, Monty, Idle. One of my heroes.

Whenever life gets you down, Mrs. Brown,
And things seem hard or tough,
And people are stupid, obnoxious or daft,
And you feel that you've had quite eno-o-o-o-o-ough,

Just remember that you're standing on a planet
That's evolving
And revolving
At nine thousand miles an hour.
It's orbiting at nineteen miles a second,
so it's reckoned,
'Round the sun that is the source of all our power.
Now the sun, and you and me,
and all the stars that we can see,
Are moving at a million miles a day,
In the outer spiral arm,
at fourteen thousand miles an hour,
Of a galaxy we call the Milky Way.

Our galaxy itself contains a hundred million stars;
It's a hundred thousand light-years side to side;
It bulges in the middle
sixteen thousand light-years thick,
But out by us
it's just three thousand light-years wide.
We're thirty thousand light-years
From Galactic Central Point,
We go 'round every two hundred million years;
And our galaxy itself is one of millions of billions
In this amazing and expanding universe.

Our universe itself keeps on expanding and expanding,
In all of the directions it can whiz;
As fast as it can go,
that's the speed of light, you know,
Twelve million miles a minute
And that's the fastest speed there is.
So remember,
when you're feeling very small and insecure,
How amazingly unlikely is your birth;
And pray that there's intelligent life
Somewhere out in space,
'Cause there's ****** all down here on Earth!

-- Eric Idle

15th Nov 2002, 10:43
Mr Mr. Draper,

I thankyou for your frank and straightforward reply to my obviously irritating question. It is a great tribute to someone of your status that you found the time to compile a comprehensive answer, and to overcome the tedium that the said answer must have induced.
Being, as you correctly state from Scotland, where the education system is far superior to our Southern counterparts my only excuse for not already being forearmed with the knowledge to answer your original question is that I must have been away that day. :p
I shall now retire to my mid-link, period, miners cottage and consider this amusing little conundrum.

I have the honour to remain your obedient servant


PS A big thankyou to Grainger .... now all is clear ..... fumbles for graph paper :D

15th Nov 2002, 13:18

I hope you put a copyright on your explanation of expansion. I would hate for Mr. G Brown to use it in his next budget to try and convince us that we aren't really paying more tax than we use too.


Tricky Woo
15th Nov 2002, 22:26
Herr Draper,

Wot you doin' talkin' 'bout astrophysics with this bunch o' 'nanas?

Right! Yer using the wrong concept to describe inflation, me old mucker. Forget the inflating balloon, and go to the swelling plum pudding. Each plum in the pud recedes from its neighbour at the same rate. The plum on t'other side of the neighbouring plum is receding at twice the rate, etc, etc.

Got it?

Good, 'cos I reckon we've got a BIG surprise coming, and the whole thing is a load of cobblers. The whole point of the Next Generation Hubble Telescope is that it will be able to see soooooo far back in time (i.e. deep into the infrared) that the universe won't be transparent enough to see anything at all, i.e. non-baryonic soup.

Mark my words: the universe will still be transparent, and one day we'll get the surprise of our lives when we start to see blue-shifted objects a long, long way away.


tony draper
15th Nov 2002, 22:35
That will be our anti selves coming back the other way Tricky.
It is already in hand,Drapes has it all planned, the anti earth will be approaching at about three quarters of light speed, before mutual anhiliation takes place, huge air bags are to be fitted to India., and deployed at just the right moment.
The other advantage we can take of this strange situation is that the bags only need to be half the size,our anti selves will obviously have deployed their own giant anti air bags to their Anti India.

PS, anti Curry would have a hell of a bang.

15th Nov 2002, 22:57
When I progress down the highway approaching V1, the cars going in the opposite direction become elongated as they pass. Their colour does not appear to change, redwise or bluewise.

Are they being doppled ? Or am I ? Or is this something to do with that Einstein chappie ?

tony draper
15th Nov 2002, 23:16
Err no thats not right, other vehicles will shrink in the direction of travel,their height will remain the same. the cars passing you should be short tall ones.
Return your car to the showroom immediatly you have obviously been sold a lemon, the warp drive is at fault, your vehicle appears only to be achieveing impulse speeds.
The buggahs prolly been clocked as well, 70,000 parsecs seems a bit low for that year.

ps, At light speeds you would see nothing ahead of you, assuming you are travelling in space and not the m25, the stars would only be visible at right angles to the direction of travel, and they would surround your vehicle like a donut, or torus as we edumacated folks calls it. ;)

16th Nov 2002, 00:45
Ah, but no. Mr Draper!

Surely you would still see the light of stars in front of your magical Ford Angular as you would be overtaking the light that they had already emitted?

This is all academic, in any case, as by this time your own grandfather would have killed you in an act of pre-emptive self-defence. (relatively-speaking, that is.)

16th Nov 2002, 07:31
Drapes theres no "center" in a 4-dimensional universe which we drink and shag around in. Yeh its a funny one to grasp, but for example if you reduce reduce our 3D dimensional world by one (and become a citizen of the 2D world - the TV screen) and its like askin someone there to please point to the cross-sectional middle between his balls and arse. He cant concieve this mysterious 3rd D. Similarley we cant concieve a 4th without breakin brains. In simple terms mate the center of the universe is.....everywhere!

tony draper
16th Nov 2002, 10:13
Indeed Mr Slash, but one can gain great insight into the mysteries of muti dimentional space time continuums by the simple expedient of purchasing a flat pack Book Case or Chest of Draws from such Emporiums as Homebase or Texas.
These are wonderous objects, obviously loosely designed around the Tesseract, one is confronted with a two dimentional set of plans,for a three dimensional object that can only possibly exist in four space.
A salutary word of warning here, under no circumstances purchase a flat pack video cabinet, these are the product of a sick mind,and are based on the Mobious Strip contained within a Kline Bottle, most were withdrawn from stock and destroyed, but apparently a few slipped thru the net.

16th Nov 2002, 15:06
Drapes, just a small point - us edumacated folks don't call a doughnut a torus :)
I mean, who'd ever want to dunk a torus? :D
Okay, so I've been caught referring to aeroplanes as planes and tori as doughnuts, but I've never called a doughnut a torus :) That would be a coffee-related sacrilidge! :D

tony draper
16th Nov 2002, 15:38
Thank you Sparks, actually the torus,is a interesting shape topographicaly speaking, not related in anyway to that Colonial bun.
The shape was discovered by Pythagorus one believes, and is modelled on the female brain. :eek:

PS. Donut is the way doughnut was spelled in the ancient Geordie language. ;)

PPS, the torus can be turned inside out thru a hole in its suface, not many people know that.

16th Nov 2002, 18:36
Well I just checked again, and them oncoming cars definitely gets stretched not squished. From this I conclude that my eyes were installed the wrong way round in my pirate-flag thing.

This explanation goes a long way to clearing up many other perplexing experiences I have had.

I don't drive a Torus - never did like Fords. The Mazda will do donuts if the road is wet though.

Empty Cruise
16th Nov 2002, 23:01
Hmmmnn, Drapes...

To the best of my reasoning, YOU are in the middle of the expanding universe. As all space & time was unified, the place you are located should have been exactly "there" and "then".

Therefore, all earthlings observe a completely uniform background radiation, thus implying that Earth was the centre of it all.

Maybe we should run a poll on it to once and for all lay Sir Fred & his theories to rest :confused:

AND - most importantly - if the universe is not expanding, the 2nd law of thermodynamics may be at risk, invalidating all my defenses agains my financial "advisor" in the bank :(


17th Nov 2002, 01:54
This all sounds like one of those 'on the way back home from the pub' conversations.