Expanding or collapsing universe?

I guess this is more a question of believe than a quesition of physics, but what will happen to the universe anyway? - Will it expand or will it collapse?

This demonstration should get you thinking:

Graphics 1024, 786, 32, 2
SetBuffer BackBuffer()
SeedRnd MilliSecs()

Type Atom
	Field x#, y#, sx#, sy#, mass#
	Field col
End Type
Global CntAtoms = 0
Const CenterMasses = True ;Wheter to align the mass center to the screen center
Global SPEED = 3

gw2 = GraphicsWidth() / 2
Color 255, 255, 255
Text gw2, 100, "Scientific experiments about the theories of the Big Bang", True
Color 255, 0, 0
Text gw2 - 200, 130, "READ FIRST:"
Color 255, 255, 255
Text gw2 - 200, 150, "Since room is physically defined by a viewpoint, we have to"
Text gw2 - 200, 170, "define a fix one. Here we will use the mass centre of the"
Text gw2 - 200, 190, "universe which will be marked by the crosshair. However, out"
Text gw2 - 200, 210, "of our view this mass centre can move, so it will be aligned"
Text gw2 - 200, 230, "to the screen centre."
Text gw2 - 200, 260, "Atoms seem to be attracted by the screen centre, which symbolizes"
Text gw2 - 200, 280, "our mass centre. It works as follows: Every atom gets attracted by"
Text gw2 - 200, 300, "all other atoms individually depending on their mass."
Text gw2 - 200, 350, "Please select an example by pressing a numeric key:"
Text gw2 - 180, 370, "[1] All atoms have the same mass"
Text gw2 - 180, 390, "[2] Every atom has its unique mass"

Repeat
	If KeyHit(1) Then
		End
	ElseIf KeyHit(2) Then
		Sample = 1
		Exit
	ElseIf KeyHit(3) Then
		Sample = 2
		Exit
	EndIf
Forever

Select Sample
	Case 1
		For x = -15 To 15
			For y = -15 To 15
				If Sqr(x * x + y * y) < 10 Then
					ay# = Rand(0, 360)
					tx# = Cos(Rand(0, 360)) * Rnd(-3, 3)
					ty# = Sin(Rand(0, 360)) * Rnd(-3, 3)
					CreateAtom(GraphicsWidth() / 2 + x, GraphicsHeight() / 2 + y, tx#, ty#, 1)
				EndIf
			Next
		Next
	Case 2
		For x = -15 To 15
			For y = -15 To 15
				If Sqr(x * x + y * y) < 10 Then
					ay# = Rand(0, 360)
					tx# = Cos(Rand(0, 360)) * Rnd(-3, 3)
					ty# = Sin(Rand(0, 360)) * Rnd(-3, 3)
					mass# = Rnd(.5, 1.5) * .5
					CreateAtom(GraphicsWidth() / 2 + x, GraphicsHeight() / 2 + y, tx#, ty#, mass#)
				EndIf
			Next
		Next
End Select

While Not KeyHit(1)
	UpdateUniverse()
	Color 255, 255, 255
	Text 10, 10, "Speed: " + SPEED
	Text 10, 25, "Cursor keys for speed up/down"
	SPEED = SPEED + KeyDown(200) - KeyDown(208)
	If SPEED < 1 Then SPEED = 1
	Flip
	Cls
Wend
End

Function CreateAtom(x, y, sx#, sy#, mass# = 1)
a.Atom = New Atom
a\x# = x
a\y# = y
a\sx# = sx#
a\sy# = sy#
a\mass# = mass# * .000001 * SPEED
a\col = (Rand(0, 255) Shl 16) Or (Rand(0, 255) Shl 8) Or Rand(0, 255)
CntAtoms = CntAtoms + 1
End Function

Function UpdateUniverse()
gw = GraphicsWidth()
gh = GraphicsHeight()
LockBuffer()
cx# = 0
cy# = 0
For a.Atom = Each Atom
	a\x# = a\x# + a\sx# * SPEED
	a\y# = a\y# + a\sy# * SPEED
	For b.Atom = Each Atom
		a\sx# = a\sx# - (a\x# - b\x#) * a\mass#
		a\sy# = a\sy# - (a\y# - b\y#) * a\mass#
	Next
	cx# = cx# + a\x# / CntAtoms
	cy# = cy# + a\y# / CntAtoms
	WritePixel a\x#, a\y#, a\col
Next
If CenterMasses Then
	For a.Atom = Each Atom
		a\x# = a\x# - (cx# - gw / 2)
		a\y# = a\y# - (cy# - gh / 2)
	Next
EndIf
UnlockBuffer()
Color 50, 50, 50
Line 0, cy#, gw, cy#
Line cx#, 0, cx#, gh
End Function

Altough it seems to me more like the universe will neither do both (see the second example)

Feel free to post your comments and opinions here! We will collapse soon or later ;)

Well, the current trend is its expanding, but thats looking at light thats taken millions of years to get here.

But, imagine if the universe collapsed, and the rate it was imploding was faster than the speed of light... We wouldnt even see it coming! :)

Generally, the universe is quite a good recycler, my initial thoughts on it is whatever happens, it'll reuse itself over and over, and quite possibly, in the bigger scheme of things, theres no beginning and theres no end. Even though Hawkings 4th dimension theory suggests otherwise... But the universe is a weird place, in my view, anything is possible, even true eternity!

*Dabz hugs a shrub*

If there is no gravity when somthing explodes,it just expands.

Until it comes into contact with somthing with gravitational pull.

Which the universe does not because,it was the first thing that exploded.

I Think . Im not a brain box.:)

does anyone know what is the speed of gravity? is it instantenous?

Is it not anti gravity that pushes all things apart in the universe?

Issac Newton sussed out gravity.Maximo

Gravity propagates at the speed of light. The sun is 8 light minutes away. If it were to disappear, it would take 8 minutes for the skies to darken, and the earth to cease orbiting. Same for electricity and magnetism. Information cannot propagate faster than the speed of light.

What about energy lost forever eg light particles that are sent out from the universe into nothingness? Nothing can ever catch them up or get them back, so over time the universe would lose energy/mass, unless it is not conserved.

But, if theres no force affecting it, it should have a uniformed rate of expansion, which it doesnt, its expanding faster.



Its a force, the bigger the mass, the higher the attraction. EDIT: And yes, Czae is right (Forgot to mention that bit!)



Some say the universe is stretching, with the clusters of matter drifting apart due to the expansion... Imagine putting dots on a flacid (I love that word) ballon with a felt tip pen then blowing it up... That effect... So whatever is making it expand, is certianly out there, yet somehow, I cannot see it being gravity, or a anti version of it.

In the words of a wise man... "God knows" ;)

Stars are emmitting light from billions of miles away,so there is no gravity.

Eh?

Light would bend if there was gravity.

sorry i think i have missed the boat here.
:(

lol, I think you have! :) hehehe

their is no sky up in the night
its just some twinkle lights that someone put up once and never took down

we are just some goldfish type enterty in someone elses dimension seeing what we want to see
the sun is just a 100w light bulb

and i think nebula would be better at typing this bullshite than me ;)

I say the universe only exists in your own mind, you make it up, it doesn't exist at all and we're all actually a part of a single unified reality.

I think you've been watching the Matrix a bit too much.

If it only exists in our mind (which I don't think is the case), then it still exists, and can be said to be expanding or collapsing.

..i think everything will end up as a one big black hole and we will all receive some nice 'n juicy MAV..

nothing to do with Matrix, he has been reading what has been echoed thru centuries by all spiritual teachers, there is only one reallity and it aint this one we are living in :P heh




Actually if this picture is correct, picture of the universe, which looks like neuron network:


then we are all imagination in the mind of God, how about that? You are not really real, you are imagination and you can puff dissappear in a second which you will do, cos like here on earth is less then a second when you take into account the wast scale of the universe and the time by which universe goes ;)

how bout it? still sounds like matrix to you :D

I think we were around before the big bang ever happened and we made it happen.

..U know wat? I think we have no idea what we are talkin about.. :)

We're all in some kid's imaginative brain?!?!

I often wonder if there's any difference between space expanding and matter shrinking. I mean, if all the atoms in the universe shrink at the same rate, whilst being held together by gravity, then it would appear to us that things are getting further away (which they are, but only because the scale of our measuring system has changed).

The universe isn't expanding or contracting. It's simply in a constant state of entropy exchange. Actions cause thoughts and thoughts cause actions. Information is lost information is found. Life goes on.

"Gravity propagates at the speed of light."

Wrong. It's ever-present and instantaneous. Which makes a sham of the current search for a 'graviton'.

Truth is we will never -really- know. It could be pulsating to the beat of an interstellar rhumba for all we know. I did read somewhere they reckon it is expanding, but actually accelerating as it expands. (which is odd as most 'explosions' slow down over time.)

The universe is expanding because when Edwin Hubble measured the red shifts of some distant galaxies he found that it increased.

Yeah that is why I asked the questiion, has there been any science done on this? how fast does reallity err, I mean gravity propagate is it really instantaneous or does it take time to propagate, can this be tested?

why should it do that?i think there is. you see, atoms have a certain radius of posible positions. an atom does not have a certain position, but a position within a certain radius, which will go less expondentional by the diameter to the center.

also i think that the universe is gonna collapse. proved is, that it expands slower than it did at the beginning. but take a look at example 2. as you see, when atoms have different masses, some of them will collapse faster than the othes and it will get to a chaos. just look at the example ;)

If we blow up the sun Earth's course will change so that we are no longer orbiting but flying off in a straight line. By measuring if this happens immediately or after 8 mins, we can tell if gravity is instant or propagates at the speed of light. Easy.

After Einstein the speed of gravity is the same as light, as Neji has brought it up, you can calc the expansion/age due to the Hubble constant and i wonder how straight the course of earth will be after blowing up the sun when the impact of the shockwave hits earth, due to the altered behaviour for the earth moon relationship as well as the impact of the rest of the gravity sources in space.

I'll tell you when the universe is about to come to an end.

Supposely dark energy causes the expansion.

Sounds like Nebula has been sharing his drugs.

Sure we would, the universe couldn't collapse faster than light and light travels the same speed for all observers irrelevant of their motion.

>>>>"Gravity propagates at the speed of light."
>>Wrong. It's ever-present and instantaneous. Which makes a sham of the current search for a 'graviton'.

This is wrong. If you "destroy" the sun - light and gravitation will reach earth in 8 minutes - otherwise gravitation is faster than light.

The effects of gravity have been observed to be faster than the speed of light.

If the sun suddenly vanished then our orbit would almost instantaneously be affected long before we could see that the sun had in fact, gone.

http://metaresearch.org/cosmology/speed_of_gravity.asp

if the universe would collapse faster than the light, which obviously is not possible, we would see it. anybody who is watching us, will not see us collapsing because out of his view it takes for ever. we see that it collapses constantly.
but since there is no 'observer' out of existance this whole theory gets ridiculous.

im pleased to know so many blitzer-physicists :) its a joy watching ya all talking about something majority of human kind has no clue :)

An interesting read Shambler. I pick up these points:

1. The article makes the case that gravity must be instatnaneous then goes on to give a speed of gravity that, although faster than the speed of light, is still a finite speed.

2. Looking round the website it seems a bit quack-mediciney. Maybe it's right. But maybe it's not. I say, don't believe things becaue they are the majority opinion, but also don't believe things just because they are the novel minority opinion.


What makes this harder to test I guess is that electricity and magnetism can be "turned off" in a way, whereas gravity can't.

Shambler thanks for that link...

I found this interesting:

How can black holes have gravity when nothing can get out because escape speed is greater than the speed of light?
or

Why do total eclipses of the Sun by the Moon reach maximum eclipse about 40 seconds before the Sun and Moon’s gravitational forces align?

If gravities speed is faster then speed of light or instantenious that must mean that we are living in a big brain where visible signals travel a bit slower then invisible gravitron siglans.

How the hell could bodies detect eachother instantly? Well they must be communicating that information thru some other dimension where traveling does not take any time, its instant...

Proff that there are another dimensions invisible to the eye but not the the wise

Yes... proof..oops 'proff' in a few sentences on some Internet forum somewhere. Unless I'm mistaken, no one here is a qualified physicst yourself included, so let's not pretend to be.

http://en.wikipedia.org/wiki/Speed_of_gravity

This Wikipedia article addresses the issues raised in that link, including aberrations and the pulsars, and concludes that the speed of gravity cannot be infinite and that it is likey to be the speed of light.

No offence, but if I have to choose between qualified physicists who devote their entire lives to the subject to become experts, or "the the wise", I'm picking Einstein.

Err.. you mean space-time?

Doing some research on the black hole issue (perhaps you should try some, took me 20 seconds on Google) it would seem that gravity can "escape" black holes because there is still matter and junk around the black hole slowly being attracted in. Because time slows the futher towards the black hole an object gets, to someone outside the black hole, there will remain lots of concentrated junk and stuff (could be a few stars' worth of matter) going round the black hole for thousands of years, giving off gravity, for a simple explanation.

I think you mean light.

No, gravity? The point was how can black holes give off gravity if light cannot escape. Well it can't, but to an outsider it takes an arbitrarily long time for the matter to eventually get sucked into the black hole.

What, give off gravity?
Gravity is currently explained as curvature of space-time, obviously its gravity thats pulling stuff in and doesn't act upon itself.

Link: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980601a.html

somebody which gets sucked into a black hole will see the whole happening in realtime, while another guy who is watching that will only see that he never ever reaches the black hole.

The person falling into the blackhole will still experience time dilation, but won't be seeing much anyway because they'll be dead before they reach the blackhole.

I think the two keywords in my statement at the top is 'Just imagine'! :P

In all respect, whatever we see in the universe is in the past, and if it did start collapsing, we wouldnt know about it until well after the collapse had begun... For all we know, it could be collapsing right now.

I'm in a position where I do generally except theories as they stand, but the universe is such a weird place that the underpinning of how we 'think' the universe works isnt or wont ever be actually right, well, for a long time yet. So in my view, theorys are what they are... just suggestions backed by maths which tend to usually have flaws but are good enough for here and now.

And when it comes to subjects like this, I generally do what Czar mentions and pushing my own thoughts aside, would back Einstien and Hawkings... simply because... I'm only a plasterer! :D

Dabz

The fascinating thing about looking at the stars is that you're not just looking into one past, you're looking into a lot of different pasts like onion skins. The nearer a star is the more up to date the information is, the more it's far away the older it is and you can see this all at the same time. Wow!

I wasn't trying to be technically accurate, just the point I was making :)

another interesting fact is that if gravity was linear, the universe would collapse. if gravity was quadratic, which it is, the universe would expand and only maybee collapse after a very long time.

The universe will eventually bit overflow and we'll all end up crunshed in a big ball.

Yes, in fact, it still does.

Where did you get that picture from?

I agree.

Black holes do emit radiation...there was a program about Hawking's work last week...I think he used to say nothing can escape a black hole but has since changed his mind.

Shambler did you read my link? I read your article, please read mine.

but they suck it back in just like they suck everything else in...

Well technically gravity doesn't suck, it pulls.
From what I've read about this Hawking radiation supposely virtual particles that form near the event horizon are seperated and because they can't annihilate, the one falling into the black hole causes it to lose mass.