'In an infinite universe, anything is possible'.
If 'infinity' is taken literally, then it is logical, if not inevitable, that anything that the human imagination can conceive, is possible and exists somewhere in infinity.
If there is some kind of boundary to the universe, what's on the other side?
There MUST be an - other side - mustn't there?
If anyone can get their head around this I'd be interested to hear their veiws.

The universe isn't infinate.

If there is some kind of boundary to the universe, what's on the other side?


nothing I guess

I dont know but i bet theres a Mcdonalds their:)

it is circular, if you could travel far enogh you would arrive back where you began.
We exist on the equivalanent to the surface of a balloon, the only place that existence occurs is on that surface.
And before you ask, no, I dont understand it either :hihi:
This I think is why we always say that God created it.
It saves us going mad trying to think about it. :help:

'In an infinite universe, anything is possible'.
If 'infinity' is taken literally, then it is logical, if not inevitable, that anything that the human imagination can conceive, is possible and exists somewhere in infinity.
If there is some kind of boundary to the universe, what's on the other side?
There MUST be an - other side - mustn't there?
If anyone can get their head around this I'd be interested to hear their veiws.
Ok. Had my cup of tea. Let me think back to A-level physics...
I was taught that, the universe is 'infinite', and there are no 'edges'. Not as far as 'we' humans are concerned anyway. Cos we don't have any equipment to prove that there is an 'edge'. I'm not sure that there are any theories out there mathematically to prove that there is an 'edge'. (Actually, even if there are, it goes beyond my knowledge cos I was only taught the basics at A-level.)

Something like, the universe that we can see, relatively, are as far as our own planets. The solar system. Cos there are gravitational forces which controls the planet movements accordingly and inter-dependently. I think that's right.

All I recall are that there's potential energies within these planet movements. So therefore....and by theory... of some 'Potential Energy' equation. Any object that is further away from the force won't have this energy, and is infinitely small, *relative* to us. So it really does not matter as far as we are concerned where the edge is, cos all we need to care about is what we can see, and what affects Earth. I don't think stars are affected by these potential energies cos there are no mass (i.e. no weight) in them.

There are stars in the universe, which we sometimes see, and we calculate their distances by 'light years'.

[Added]Oh I should add the reason I added the star bit is that. If we detect a new star which is waaaaaay far. Then we know that the universe is that bit bigger than what we thought it was. Who's to say that in the future, we may not see a little square boxed shape created by the stars' distances ? :hihi: Then we'll know we live in a box shaped universe.

The universe isn't infinate.
I see, thanks for clearing that up. Any idea why?

There is a kind of edge to the universe. According to the big bang theory there was a huge explosion that would have produced everything, including lots of radiation and light. The light would then move from the centre of the blast at (not surprisingly) the speed of light. Nothing goes faster than light. So that first light, which is still shooting away from the centre of the universe marks a limit beyond which absolutely nothing can exist. There is no "other side".

Nothing goes faster than light.

What about the speed of dark?

If you open your door at night, the first thing you see is the dark...

Back to the Original question:- It's a relative thing...

So then you have to ask, do you define the edge as its existence in itself, or do you define the edge as where that light have been ?

light -------------------------> |<- here? . . . . . . . . . or |<-here ?



Okie doke. At times like this, I feel geeky.

What about the speed of dark?

If you open your door at night, the first thing you see is the dark...

Back to the Original question:- It's a relative thing...
Ok. Give me the 'Speed of Dark' in its unit. lol.
I will give u a nobel Prize if you can define it ! :loopy: :P

'Speed of light' is "c", and it has a unit, and it is used in many equations and theories.

But is the Universe a bag, a balloon or a box?

The only thing which actually moves faster than light (apart from the theoretical tachyon) is bad news. Attempts to use bad news as a fuel for Faster Than Light (FTL) starships have stonewalled due to the consequence that wherever you arrive nobody wants to see you.

'Speed of light' is "c", and it has a unit, and it is used in many equations and theories.
Indeed, even in the most famous equation in the world! I'd bet 90% of people wouldn't have known what the 'c' stood for if asked though.

The only thing which actually moves faster than light (apart from the theoretical tachyon) is bad news. Attempts to use bad news as a fuel for Faster Than Light (FTL) starships have stonewalled due to the consequence that wherever you arrive nobody wants to see you.
I used to have the Douglas Adams quote as my signature, it's one of my favourite lines from the Hitchhiker books.

Charlie (Einstein?) :huh:

Ok. Give me the 'Speed of Dark' in its unit. lol.
I will give u a nobel Prize if you can define it ! :loopy: :P

'Speed of light' is "c", and it has a unit, and it is used in many equations and theories.

Keep talking dirty! ;)

Charlie (Einstein?) :huh:
Or More Cash 2 you.

If there is some kind of boundary to the universe, what's on the other side?
There MUST be an - other side - mustn't there?


You're thinking as though the universe is what you see, and what you're used to. 200 years ago we thought the Earth was flat, there's no way we can even comprehend what lies in the distant parts of the universe.

The universe is expanding at an increasing rate, whos to say that distant particles are not traveling so fast that we will never be able to see the "edge" of the universe? Because the light will never reach us, and we'll never be able to travel fast enough to reach it.

The truth is we don't know, so crack open a beer and save yourself the headaches :)

Or More Cash 2 you.
lol. Good one. :thumbsup:

Keep talking dirty!
Nutter ! :loopy:

The only thing which actually moves faster than light (apart from the theoretical tachyon) is bad news. Attempts to use bad news as a fuel for Faster Than Light (FTL) starships have stonewalled due to the consequence that wherever you arrive nobody wants to see you.
faster then bad news is when some famous person has some bad accident and the sick jokes are there faster then then the speed of anything..

But is the Universe a bag, a balloon or a box?
It is topographically similar to a torus, according to recent theories. Mmm, doughnuts...

Hard to tell who's being facetious and who's being idiotic on this thread :hihi:


Anyway; check out "privative" in the dictionary. Infinity is a privative. (So is "dark," if anyone seriously wants to know what the speed of dark is.)

Hard to tell who's being facetious

I fall into this category..

If anyones interested in some various theories on the speed of dark then follow this link (http://www.freakface.com/speedofdark/)

It touches on the original question in one of the theories, so is relevant and contributive to this thread...

'In an infinite universe, anything is possible'.
If 'infinity' is taken literally, then it is logical, if not inevitable, that anything that the human imagination can conceive, is possible and exists somewhere in infinity.
If there is some kind of boundary to the universe, what's on the other side?
There MUST be an - other side - mustn't there?
If anyone can get their head around this I'd be interested to hear their veiws.

The universe is approximately 13.8 billion light years across, not infinite.

What about the speed of dark?

If you open your door at night, the first thing you see is the dark...

Back to the Original question:- It's a relative thing...

Prove there is dark then. Without light, there'd be no dark, because you wouldn't know it was dark without light.

I have a pretty good grasp of physics, I think you've got something a bit mixed up in there somewhere...

Ok. Had my cup of tea. Let me think back to A-level physics...
I was taught that, the universe is 'infinite', and there are no 'edges'. Not as far as 'we' humans are concerned anyway. Cos we don't have any equipment to prove that there is an 'edge'. I'm not sure that there are any theories out there mathematically to prove that there is an 'edge'. (Actually, even if there are, it goes beyond my knowledge cos I was only taught the basics at A-level.)

Something like, the universe that we can see, relatively, are as far as our own planets. The solar system. Cos there are gravitational forces which controls the planet movements accordingly and inter-dependently. I think that's right.
I personally can see a damn site further than that. Look out the window, the nearest star is around 4 light years away, so all those stars you can see, further than that!


All I recall are that there's potential energies within these planet movements. So therefore....and by theory... of some 'Potential Energy' equation. Any object that is further away from the force won't have this energy, and is infinitely small, *relative* to us.
eh?

So it really does not matter as far as we are concerned where the edge is, cos all we need to care about is what we can see, and what affects Earth. I don't think stars are affected by these potential energies cos there are no mass (i.e. no weight) in them.

There is no edge, it's all about multidimensional topography

There are stars in the universe, which we sometimes see, and we calculate their distances by 'light years'.
Which as the name suggests is the distance light travels in 1 year. Or 6.8 *10^13 miles.


[Added]Oh I should add the reason I added the star bit is that. If we detect a new star which is waaaaaay far. Then we know that the universe is that bit bigger than what we thought it was. Who's to say that in the future, we may not see a little square boxed shape created by the stars' distances ? :hihi: Then we'll know we live in a box shaped universe.

I think we currently estimate the size based on the microwave background radiation.

You're thinking as though the universe is what you see, and what you're used to. 200 years ago we thought the Earth was flat, there's no way we can even comprehend what lies in the distant parts of the universe.

The universe is expanding at an increasing rate, whos to say that distant particles are not traveling so fast that we will never be able to see the "edge" of the universe? Because the light will never reach us, and we'll never be able to travel fast enough to reach it.

The truth is we don't know, so crack open a beer and save yourself the headaches :)

Certainly, and given the oscillating universe theory, we'll be long dead before the whole thing collapses under its own gravity.

If that one is right.

Of course.

I think we currently estimate the size based on the microwave background radiation.

Pretty much. It was by the red shift in the light spectrum with the really distant galaxies, and/or quasars. Now, however, that background radiation can be more accurately, and easily detected, that tends to be used.

It's usually described as the 'echo' from the Big Bang.

A party which sounded fun.

Ok. Had my cup of tea. Let me think back to A-level physics...
I was taught that, the universe is 'infinite', and there are no 'edges'. Not as far as 'we' humans are concerned anyway. Cos we don't have any equipment to prove that there is an 'edge'. I'm not sure that there are any theories out there mathematically to prove that there is an 'edge'. (Actually, even if there are, it goes beyond my knowledge cos I was only taught the basics at A-level.)

Something like, the universe that we can see, relatively, are as far as our own planets. The solar system. Cos there are gravitational forces which controls the planet movements accordingly and inter-dependently. I think that's right.

All I recall are that there's potential energies within these planet movements. So therefore....and by theory... of some 'Potential Energy' equation. Any object that is further away from the force won't have this energy, and is infinitely small, *relative* to us. So it really does not matter as far as we are concerned where the edge is, cos all we need to care about is what we can see, and what affects Earth. I don't think stars are affected by these potential energies cos there are no mass (i.e. no weight) in them.

There are stars in the universe, which we sometimes see, and we calculate their distances by 'light years'.

[Added]Oh I should add the reason I added the star bit is that. If we detect a new star which is waaaaaay far. Then we know that the universe is that bit bigger than what we thought it was. Who's to say that in the future, we may not see a little square boxed shape created by the stars' distances ? :hihi: Then we'll know we live in a box shaped universe.

does anyone remember paul calf's famous catchphrase?

The only thing which actually moves faster than light (apart from the theoretical tachyon) is bad news. Attempts to use bad news as a fuel for Faster Than Light (FTL) starships have stonewalled due to the consequence that wherever you arrive nobody wants to see you.

lol

nice one sharper :hihi:

does anyone remember paul calf's famous catchphrase?

I'm sure that "Bago" isn't meant to be a large part of that :hihi:

infinity is infinite

however, the universe, in the frequency range that we're currently aware of, is not

tho saying that, the universe at large, the so called "external" universe, is a projection of our inner selves

and seeing as we're infinite, you could see this "external" expression of our "inner" selves as infinite

I'm sure that "Bago" isn't meant to be a large part of that :hihi:

well, it's the first half of it ...

Well, the guy did ask. Ask a daft question, and you'd get a daft answer. He actually didn't structure it very well. :rolleyes:

Anyway, it all stemmed from this morning little activity. Seems a bit pointless now. Never mind.

I have a pretty good grasp of physics, I think you've got something a bit mixed up in there somewhere...
Well, I did say that from what I can remember...

I personally can see a damn site further than that. Look out the window, the nearest star is around 4 light years away, so all those stars you can see, further than that!
Can you ? You have x-ray eyes ? Wow... The stars that you can see, yes, but are the furthest ones away that you can see with your naked eyes ?

eh?
I was talking about the gravitational potential fields within planets.

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

I'd love to add to the debate but it is clearly futile. As a great philosopher once pointed out, the only certainty in the known universe is that, if you think about it too hard you'll wind up, like these fools!! (http://www.columbia.edu/cu/record/23/15/11c.gif)

Well, I did say that from what I can remember...

how about refreshing your memory before you try to help us poor folks out here


Can you ? You have x-ray eyes ? Wow... The stars that you can see, yes, but are the furthest ones away that you can see with your naked eyes ?



what has having x-ray eyes got to do with being able to see further than the edge of our solar system?

as paul calf so aptly said ...

X-ray is used to detect matters out in the universe. Stars omits light, so we can see it. Matters like blackholes, we can only tell by small mass particles hitting it, and omitting x-rays. So we know it's there. I thought that some stars can also omit x-rays too.

Anyway, I was trying to recall from memory, rather than do a Google. If the guy was interested, he could've just looked it up anyway. Why bother asking ?? :rolleyes:

what has having x-ray eyes got to do with being able to see further than the edge of our solar system?

as paul calf so aptly said ...

X-rays were the first things which, given our current understanding of astrophysics, tied in with the theories for pulsars (astronomical signposts as a result), quasars, and black holes, for three examples.

Nothing goes faster than light

tho of course Quantum Entanglement theory seems to suggest that information can be transmitted instantaneously between paired particles over any distance, hinting at a connection beyond the spacetime dimension

now THAT's where infinity lies (IMHO)

the zero point

X-ray is used to detect matters out in the universe. Stars omits light, so we can see it. Matters like blackholes, we can only tell by small mass particles hitting it, and omitting x-rays. So we know it's there. I thought that some stars can also omit x-rays too.

i think you mean emit, not omit

if stars omitted light then we'd be up the creek without, erm, any eyes or even not up any creek cos life as we know it would not exist

yeah of course stars emit x-rays, which are electromagnetic waves of a certain frequency, as well as many other frequencies of electromagnetic radiation - some of these emissions are visible to our eyes and we call them light - others are invisible to our eyes but we feel them as heat - many others we do not feel at all

but what has that got to do with having x-ray eyes? by that i take it you mean eyes that can see thru things like superman?

Anyway, I was trying to recall from memory, rather than do a Google. If the guy was interested, he could've just looked it up anyway. Why bother asking ?? :rolleyes:

you could ask the same about half the posts on this or any other forum

why bother replying if your answer is neither going to add intelligent direction to the debate nor at least be a good ol' stoopeed peas tek?

have some rolleyes :rolleyes:

X-rays were the first things which, given our current understanding of astrophysics, tied in with the theories for pulsars (astronomical signposts as a result), quasars, and black holes, for three examples.

and were they detected by x-ray eyes then?

There is a kind of edge to the universe. According to the big bang theory there was a huge explosion that would have produced everything, including lots of radiation and light. The light would then move from the centre of the blast at (not surprisingly) the speed of light. Nothing goes faster than light. So that first light, which is still shooting away from the centre of the universe marks a limit beyond which absolutely nothing can exist. There is no "other side".

You missed a few words out. Nothing goes faster than light — as far as we know!

repeat..................

PingPang: Now who's doing a Paul Calf ? Omit, emit. It was a typing mistake, okay ? Is it not allowed ?!?!?!!?!?!?!?!??!!?!?! I know it didn't look quite right when I wrote amit, but it sounded like omit, but I meant emit, okay ? It's late, and I don't give a damn any more.

Sods.

Be a pedantic sod as much as you like. I was merely being helpful, and didn't want to point out the obvious to the OP. Not in the mood now to nitpik back.

PingPang: Now who's doing a Paul Calf ? Omit, emit. It was a typing mistake, okay ? Is it not allowed ?!?!?!!?!?!?!?!??!!?!?! I know it didn't look quite right when I wrote amit, but it sounded like omit, but I meant emit, okay ? It's late, and I don't give a damn any more.

Sods.

Be a pedantic sod as much as you like. I was merely being helpful, and didn't want to point out the obvious to the OP. Not in the mood now to nitpik back.

lol

your lil mistake kinda changed the whole meaning of your reply, which i wouldn't count as helpful, but more of a hinderance

i can nitpick all day and all night wotevva mood i'm in

i'm a sod like that

lol

what "obvious" didn't you want to point out to the OP? from his question i'd deduce that the obvious needs to be pointed out to him/her - in fact it i'd hazard a guess that the obvious is all he or she would be able to understand

or am i just being a sod again?

it wouldn't surprise me one tiny bit if i was

and were they detected by x-ray eyes then?

If Jodrell Bank counts as such .........

If Jodrell Bank counts as such .........

no ... only the eyes of superman come anywhere near that ... and i'm sure that his eyes can fire lasers too ...

You missed a few words out. Nothing goes faster than light — as far as we know!

True, however theorists can allow for it, but then I suppose they can allow for pink elephants, which are invisible to humans making up all the dark matter which we now believe to pervade the cosmos.

Going back to the "What is outside the universe?" question, given that there is a vast amount (nearly all, in point of fact) of space which is 'empty', it's not too hard to grasp the concept of 'nothingness' outside of the Universe.

Let's think about how we are told that the atom exists. An atom of hydrogen, with one proton and one neutron, as its nucleus, and then, relatively, a HUGE distance to the one electron which circles the nucleus.

In interstellar space, it is theorised, there are MASSIVE distances between each atom. Even allowing for dark matter, there would be vast tracts of the 'known' Universe with nothing there; so why is it so odd that the same state can't exist elsewhere? By that, I mean a finite Universe, which fits current cosmology.

Of course, it's only a few hundred years ago when most thought the world was flat, so maybe our musings in a thousand years will be the subject of mirth too.

I suspect it's our minds which can't understand 'nothing' properly, because we have 'something' wherever we look.

no ... only the eyes of superman come anywhere near that ... and i'm sure that his eyes can fire lasers too ...

If someone could just give me the X-ray specs which were advertised in the Beano, which we KNEW would allow us to see nekkid wimmin, I'd die a happierhippy :love: :hihi:

Unfortunately however, I'll have to settle for the X-Ray Specs as a band, I fear ........

If someone could just give me the X-ray specs which were advertised in the Beano, which we KNEW would allow us to see nekkid wimmin, I'd die a happierhippy :love: :hihi:
.

that'd do nicely, sir

Going back to the "What is outside the universe?" question, given that there is a vast amount (nearly all, in point of fact) of space which is 'empty', it's not too hard to grasp the concept of 'nothingness' outside of the Universe.

The bit that's hard to grasp is:-

It's not strictly true to say that outside of the Universe, there's nothing there. There isn't even any "there" to have nothing in it!

Our minds simply can't think in four dimensions. We evolved on a three-dimensional planet, and our minds with us. The best analogy is the one given earlier, to imagine creatures which are absolutely (sensewise, as well as movementwise) confined to the surface of a balloon. Their world doesn't have an edge, and doesn't have a centre, but it is not infinite - the centre of their two-dimensional world is in a third dimension, totally unreachable and unknowable to them. If someone blows up the balloon, their world expands - but it's not expanding INTO anything (so far as they are concerned), it's just that the distances between various parts of the balloon are increasing.

The centre and edges of OUR Universe are in a fourth dimension, equally unreachable and unknowable to us. In terms of our reality, that central point, and the edges of the Universe, simply do not exist. Our Universe is expanding, but not "into" anything - it's just that the distance between various parts of it are increasing.

At least, that's the best stab *I* can make at understanding what the hell is going on. Haldane's Law still stands.

The centre and edges of OUR Universe are in a fourth dimension, equally unreachable and unknowable to us. In terms of our reality, that central point, and the edges of the Universe, simply do not exist. Our Universe is expanding, but not "into" anything - it's just that the distance between various parts of it are increasing.

At least, that's the best stab *I* can make at understanding what the hell is going on. Haldane's Law still stands.

This is a good stab at explaining it. I hope SuperTyke doesn't mind me pasting from a PM I sent him - but I would add this:


When we speak of the universe "being infinite", modern cosmology is not really saying "there is an infinite number of stars"

Otherwise - the maths of things gets really silly - ie. the old argument that in an infinite number of galaxies there would be an infinite number of stars. Of these a proportion would have earth sized planets, a proportion would have life, a proportion inteligent life.. etc. As any % of infinity is infinity, then there are (by logic) an infinite number of earth type planets supporting inteligent life.

Therefore you could suggest that on one of these worlds there is a Sheffield Forum where the users ARE actually intelgent geese - and one could call himself "Mr Monkey"...

Modern cosmology suggests that the universe is 3d spatialy infinite, but "bounded" ie it conatins a finite number of stars, but you could still travel in straight line forever within it. Just as you can walk on the 2d surface of the earth forever in a straight line without falling off the edge...

What about the speed of dark?

If you open your door at night, the first thing you see is the dark...

Back to the Original question:- It's a relative thing...

darkness is simply the absence of light :)

The bit that's hard to grasp is:-

It's not strictly true to say that outside of the Universe, there's nothing there. There isn't even any "there" to have nothing in it!

Our minds simply can't think in four dimensions. We evolved on a three-dimensional planet, and our minds with us. The best analogy is the one given earlier, to imagine creatures which are absolutely (sensewise, as well as movementwise) confined to the surface of a balloon. Their world doesn't have an edge, and doesn't have a centre, but it is not infinite - the centre of their two-dimensional world is in a third dimension, totally unreachable and unknowable to them. If someone blows up the balloon, their world expands - but it's not expanding INTO anything (so far as they are concerned), it's just that the distances between various parts of the balloon are increasing.

The centre and edges of OUR Universe are in a fourth dimension, equally unreachable and unknowable to us. In terms of our reality, that central point, and the edges of the Universe, simply do not exist. Our Universe is expanding, but not "into" anything - it's just that the distance between various parts of it are increasing.

At least, that's the best stab *I* can make at understanding what the hell is going on. Haldane's Law still stands.

True. The bit I was getting was that in our 3-D Universe, there are parts which are 'nothing', but you're right, we can't think in 4-D.

Unless you count the abstract dimension of time ........

Modern cosmology suggests that the universe is 3d spatialy infinite, but "bounded" ie it conatins a finite number of stars, but you could still travel in straight line forever within it. Just as you can walk on the 2d surface of the earth forever in a straight line without falling off the edge...

I believe they call it "finite but unbounded," rather than the other way around - because, as you say, although the Earth is only so big, you can move directly forwards forever and never reach an end of it.

no ... only the eyes of superman come anywhere near that ... and i'm sure that his eyes can fire lasers too ...

I think your humour's wasted on some posters here, PingPang!

StarSparkle :)

does anyone remember paul calf's famous catchphrase?
From wikipedia, I'm not sure whether you mean

"Look I'm not messing about, if you want a shag I'll be in the cubicle. Leave it about twenty minutes, I'll be having a dump."

Or

"Forgive me but you've got **** shoes on, you ****ty shoed *******!"

Either way, I'd be worried if I were Bago (really I would)

Probably: "It's a f*****g paradigm!"

I think your humour's wasted on some posters here, PingPang!

StarSparkle :)

i agree, Ms Star! however, i'll keep trying - even if i only end up trying people's patience!

From wikipedia, I'm not sure whether you mean

"Look I'm not messing about, if you want a shag I'll be in the cubicle. Leave it about twenty minutes, I'll be having a dump."

Or

"Forgive me but you've got **** shoes on, you ****ty shoed *******!"

Either way, I'd be worried if I were Bago (really I would)
That's not what I found on Wikipedia. :suspect:

Anyway, I'm too young to know the Paul Calf's phrase. :cool: :cool:
They say there's no cure for Pendanticistis. Aww....

From wikipedia, I'm not sure whether you mean

"Look I'm not messing about, if you want a shag I'll be in the cubicle. Leave it about twenty minutes, I'll be having a dump."

Or

"Forgive me but you've got **** shoes on, you ****ty shoed *******!"

Either way, I'd be worried if I were Bago (really I would)

lol

nice try Crayfish, but no cigar

try his most famous catchphrase - technically it's three words, but it sounds like one word when said as it shud be

from the post above i reckon Ms Bago might have caught on ...

True. The bit I was getting was that in our 3-D Universe, there are parts which are 'nothing', but you're right, we can't think in 4-D.

Unless you count the abstract dimension of time ........

sorry if Bago thinks i'm being a pedant yet again (ok to be truthful no i'm not sorry, it's just one of those polite phrases that slips from my fingers occasionally)

(btw according to the venerable wikipedia, Being called a pedant, or pedantic, is considered insulting. However some people take pride in being a pedant, especially with regard to the use of the English language. - yup thasmeeeee!)

anyway, we think in 4 dimensions as a matter of course - we inhabit "spacetime", which is space and time together - the two cannot exist independently, so we must count the abstract dimension of time - time is the so called fourth dimension - to meet someone you need all four dimensional coordinates otherwise you'll miss them - eg wot time are we meeting dahn which pub?

it is difficult to think outside of our normal 4D framework tho, i agree

:D

anyway, we think in 4 dimensions as a matter of course - we inhabit "spacetime", which is space and time together - the two cannot exist independently, so we must count the abstract dimension of time - time is the so called fourth dimension - to meet someone you need all four dimensional coordinates otherwise you'll miss them - eg wot time are we meeting dahn which pub?

it is difficult to think outside of our normal 4D framework tho, i agree

:D


Time is not a dimension in the normal sense of the word. It's a product of the Universe, one way or another.


It's been popularly called a "dimension" at least since H.G. Wells used exactly the point you raise above about needing four co-ordinates to pinpoint something, but this is actually a misnomer.

Time is not a dimension in the normal sense of the word. It's a product of the Universe, one way or another.


It's been popularly called a "dimension" at least since H.G. Wells used exactly the point you raise above about needing four co-ordinates to pinpoint something, but this is actually a misnomer.

yeah i agree

i was quoting happyhippy when i mentioned "the abstract dimension of time"

time doesn't exist separately from space, and isn't a dimension, as you say, in the normal sense of the word - i don't think space is a dimension in the normal sense of the word either - it's pointless speaking about time unless it's linked with space - the spacetime dimension

:thumbsup:

yeah i agree

i was quoting happyhippy when i mentioned "the abstract dimension of time"

time doesn't exist separately from space, and isn't a dimension, as you say, in the normal sense of the word - i don't think space is a dimension in the normal sense of the word either - it's pointless speaking about time unless it's linked with space - the spacetime dimension

:thumbsup:

Agreed, but time is abstract as there is no constant. However to understand space, we have to have "time", for which we created our own constant.

Speaking astronomically, I suppose red shift is the best marker of "time" we have ........

Agreed, but time is abstract as there is no constant. However to understand space, we have to have "time", for which we created our own constant.

Speaking astronomically, I suppose red shift is the best marker of "time" we have ........

i don't think that there is any physical constant as such, either - there is no such thing as a "solid" thing in the newtonian sense

also i don't think time is about understanding space - they both need each other as they are intrinsicly bound & intertwined - spacetime - they cannot be separated

:D

I can remember being almost offended and quite stunned when my thoughts and theory that the realms of imagination were infinite, and that imagination had no limits were challenged by a physics-orientated pal who insisted that there had to be a limit to the mind and its activities because it was enclosed in a physical form: it had a physical limit

:|

i don't think that there is any physical constant as such, either - there is no such thing as a "solid" thing in the newtonian sense

also i don't think time is about understanding space - they both need each other as they are intrinsicly bound & intertwined - spacetime - they cannot be separated

:D

Thet depends on your definition of "space" (meaning distance), and "time". Both are distorted at the extremities of the Universe.

Thet depends on your definition of "space" (meaning distance), and "time". Both are distorted at the extremities of the Universe.
they may be distorted but they cannot be separated

spacetime

I can remember being almost offended and quite stunned when my thoughts and theory that the realms of imagination were infinite, and that imagination had no limits were challenged by a physics-orientated pal who insisted that there had to be a limit to the mind and its activities because it was enclosed in a physical form: it had a physical limit

:|

looks like ur mate was confusing the mind with the brain

they may be distorted but they cannot be separated

spacetime

On a universal scale, no, they can't; but as far as mundane activities and measurements go, they are effectively separate things. Nobody has to consider four-dimensional spacetime properties when designing the width, height and depth of a house.

tho of course Quantum Entanglement theory seems to suggest that information can be transmitted instantaneously between paired particles over any distance, hinting at a connection beyond the spacetime dimension

now THAT's where infinity lies (IMHO)

the zero point

If you want to go all Quantum on me then I'll be right here moving at an indeterminate speed, or I'll be moving at a specific speed somewhere indeterminate. Possibly in the direction of a primer on quantum physics :)

Can something really go on forever?

Surely that would be a bit boring wouldn't it?

Maybe this post is going to be infinite!

Who knows, we wont because if something is going to be infinite or even if infinity exsists the chances are non-one will ever find out, it will out live all of us, thats us mortals anyway!

If you want to go all Quantum on me then I'll be right here moving at an indeterminate speed, or I'll be moving at a specific speed somewhere indeterminate. Possibly in the direction of a primer on quantum physics :)

Strictly speaking you will have a determinate speed and direction. it's just that measuring one will alter the other, so we can never know what both of them are at the same time.
Superposition, that's much more mind bending, things that are in or more states and don't drop down into just one until you look at it.

Heisenberg uncertainty principle (http://en.wikipedia.org/wiki/Uncertainty_principle)

Can something really go on forever?

Surely that would be a bit boring wouldn't it?

Have you seen the ending of Lord of the Rings 3?

Can something really go on forever?

Surely that would be a bit boring wouldn't it?

Maybe this post is going to be infinite!

Who knows, we wont because if something is going to be infinite or even if infinity exsists the chances are non-one will ever find out, it will out live all of us, thats us mortals anyway!
Well, only light can go on infinitely in a vacuum where there is no mass.

Hence the comment made previously to say that light is still expanding this universe. Because of this shot of light from the big bang. (Actually, I didn't know this, but it's interesting...)

E = mc(2)

Can something really go on forever?

The list of whole numbers.

The list of whole numbers.
Also, the list of prime numbers. The proof of which is fun.

On a universal scale, no, they can't; but as far as mundane activities and measurements go, they are effectively separate things. Nobody has to consider four-dimensional spacetime properties when designing the width, height and depth of a house.

lol

of course you can measure individual spacetime properties, like how long did it take you to write that post or how long are your fingers, but the post or your fingers exist in spacetime

your fingers only have a property of length or "physical size" as part of their existence in spacetime

you can measure individual properties like time & size, but they only exist as part of the whole spacetime thingummyjig, and not independantly

you can't escape from that fact

If you want to go all Quantum on me then I'll be right here moving at an indeterminate speed, or I'll be moving at a specific speed somewhere indeterminate. Possibly in the direction of a primer on quantum physics :)

you wavicle!

:thumbsup:

sounds like a plan!

Also, the list of prime numbers. The proof of which is fun.
I was sure someone would have asked me for the proof by now. I suppose those who are bothered already know it.

lol

of course you can measure individual spacetime properties, like how long did it take you to write that post or how long are your fingers, but the post or your fingers exist in spacetime

your fingers only have a property of length or "physical size" as part of their existence in spacetime

you can measure individual properties like time & size, but they only exist as part of the whole spacetime thingummyjig, and not independantly

you can't escape from that fact

Which is why I agreed with you. *sigh*

It will probably be helpful to understand this issue if you think of infinity as a balloon. The "gas" inside the balloon is everything and so is infinite. However, the material that makes up the balloon is infinity because it enclosed the infinite. The material must be very thin, almost non existant, yet it must exist. Because it is so thin you might think that some of the infinite material might escape but it has nowhere to escape to since nothing exists outside the balloon so it stays where it is. Outside the balloon doesn't exist, but it must exist for the balloon to have an outside. I hope that clears this up once and for all.

It will probably be helpful to understand this issue if you think of infinity as a balloon. The "gas" inside the balloon is everything and so is infinite. However, the material that makes up the balloon is infinity because it enclosed the infinite. The material must be very thin, almost non existant, yet it must exist. Because it is so thin you might think that some of the infinite material might escape but it has nowhere to escape to since nothing exists outside the balloon so it stays where it is. Outside the balloon doesn't exist, but it must exist for the balloon to have an outside. I hope that clears this up once and for all.

That won't help at all. Clearly the gas inside the baloon occupies a finite volume, much as the space 'inside' the universe is finite.

The universe is not infinite, it has a measurable size.

.

The universe is not infinite, it has a measurable size.


:confused:
Not if you are thinking along the line of how far it is from Doncaster to Scunthorpe

You could travel in a straight line for ever in the universe, but that dont make it infinite,,,

The preson who posted the balloon analogy is correct..

No they aren't. They said that the contents of the balloon represent infinity when clearly they do not, any bounded region by definition is finite.

The fact that spacetime is curved in 4 dimensions and loops back on itself doesn't make the 3 dimensional space so enclosed infinite, it just means that you can't determine where the 'edge' is.

Go back to the 2d ants on a balloon surface. They can crawl around forever, but the surface area of the balloon is finite and measurable despite that.

The list of whole numbers.

Or the list of non-integers between 0 and 1 (or 0-0.1, or 0-0.01):D.

they may be distorted but they cannot be separated

Tachyon particles can (and do - theoretically) exist "out of time":).

'In an infinite universe, anything is possible'.
If 'infinity' is taken literally, then it is logical, if not inevitable, that anything that the human imagination can conceive, is possible and exists somewhere in infinity.
If there is some kind of boundary to the universe, what's on the other side?
There MUST be an - other side - mustn't there?
If anyone can get their head around this I'd be interested to hear their veiws.
universe is not infinite. in fact, it is shrinking.

Still growing actually, I think. Theorised to shrink at some point though maybe possibly.

The universe is not infinite, it has a measurable size.

Can't fault your conviction Cyclone, but as we don't possess any physical means of actually measuring the universe, maths don't convince me.

It's always been a dicotomy for me, - I find it just as difficult to get my head around the concept that space is infinite, as I do that it is finite!!

So how about the next part of the question?
If we assume that space is infinite, would absolutely ANYTHING then be possible?
Just to stay a little bit within the realms of sanity, let's assume that the laws of physics are universally constant. Gravity - light years - (5.88 trillion miles) etc etc.
Infinite numbers of life supporting planets would give life to infinite numbers of life forms. Some say that ANY shape of creature that can be imagined could be alive - or have lived - somewhere sometime> what about it guys!!?

So it's purely hypothetical now based on an infinite universe which doesn't exist... Okay.

An infinite number of species divided over an infinite amount of volume means that there are 1 species in any given area. This clearly isn't the case as I can look up at mars and find 0 species in that area. So some part of the premise must be flawed.
If the flaw is that there is an infinite number of species, then you get, finite number of species divided into infinite space. Number of species in a given volume equals 0. Since I can prove that wrong (look at earth there's apparently 1 here), then this postulation can't be correct.

Clearly the 3rd option doesn't work, infinite species/finite space. Things would be a wee bit crowded.

So only the 4th option is left as being supported by observation, finite species/finite volume. Given that finite/finite can give us any real number result, this one is supported by the evidence so far.

Hope you can follow my logic there.

Can't fault your conviction Cyclone, but as we don't possess any physical means of actually measuring the universe, maths don't convince me.


Do you really believe that the moon is 2 light seconds from earth? No one has been up there with a large tape measure, we only have maths to support it...

So it's purely hypothetical now based on an infinite universe which doesn't exist... Okay.

An infinite number of species divided over an infinite amount of volume means that there are 1 species in any given area. This clearly isn't the case as I can look up at mars and find 0 species in that area. So some part of the premise must be flawed.


There are various different inifinities, so that logic isn't quite right. For example, consider a hotel with an infiinite number of floors, and an infinite number of rooms on each floor. Now suppose that only alternate rooms are occupied.

Or, if you prefer, consider that there are an infinite number of whole numbers, only half of which are odd.

That said, cyclone is right that the universe is not infinite, we know its size, mass, and age.

Infinite numbers of life supporting planets would give life to infinite numbers of life forms. Some say that ANY shape of creature that can be imagined could be alive - or have lived - somewhere sometime> what about it guys!!?

In an infinitely large universe (if this was one, which it is not), then everything - EVERYTHING - that is theoretically possible, would have happened somewhere. This includes, to take one example, a planet which is exactly the same as this one in every single detail except that you spell your forum nickname as Supertike.

Which is why I agreed with you. *sigh*

soz mate, didn't look that way to me but then my eyes often deceive me ...

:D

So it's purely hypothetical now based on an infinite universe which doesn't exist... Okay.

An infinite number of species divided over an infinite amount of volume means that there are 1 species in any given area.

The maths doesn't hold out here I'm afraid.

Imagine that you have an apple and two oranges in every square meter. Imagine that there are an infinite amount of square meters.

You therefore have an infinite amount of oranges and an infinite amountr of apples. But you know that there is not 1 apple in any given area and 1 orange in the same given area.

You are treating infinity as if it was an undefined amount, essentially a number. Infinity is not a number.

The maths doesn't hold out here I'm afraid.

Imagine that you have an apple and two oranges in every square meter. Imagine that there are an infinite amount of square meters.

You therefore have an infinite amount of oranges and an infinite amountr of apples. But you know that there is not 1 apple in any given area and 1 orange in the same given area.

You are treating infinity as if it was an undefined amount, essentially a number. Infinity is not a number.

I should really finish reading the thread before posting a comment.... My bad

soz mate, didn't look that way to me but then my eyes often deceive me ...

:D

My point was, what you said it true, but the the purposes of ordinary living here on earth, we don't need to care whether it is or not.

Since most people are laymen and not cosmologists - amateur or otherwise - that means to all intents and purposes, as far as they're concerned, it's a load of fetid dingo's kidneys. :hihi:

Can't fault your conviction Cyclone, but as we don't possess any physical means of actually measuring the universe, maths don't convince me.

I'm sorry maths doesn't convince you, and I completely fail to understand why. Maths is merely logic.

Do you really believe that the moon is 2 light seconds from earth? No one has been up there with a large tape measure, we only have maths to support it...

The means of measurement to which I refer Cyclone, are not yet available to science. Unless of course, you know of a method of transmitting and receiving signals that travel many many times faster than light.

Incidently, please lighten up a little, your patronising manner is not really necessary, especially on a subject that top physicists and mathematicians have yet to agree. And I'm so sorry if the nature of the universe is too piddling a little matter for you, taxing your patience as it does, trying to explain it all to we lesser humans.

How stupid of me not to realise that there are many different infinities!
I posed this question as a little invitation for forumers to share thoughts and imaginings - in this hypothesis, imaginings that are possible if not provable.
No need for heavy reasoning, just thought it might be - dare I say it? - Fun.

In an infinitely large universe (if this was one, which it is not), then everything - EVERYTHING - that is theoretically possible, would have happened somewhere. This includes, to take one example, a planet which is exactly the same as this one in every single detail except that you spell your forum nickname as Supertike.

Or superdyke. Ya lesbian.

The maths doesn't hold out here I'm afraid.

Imagine that you have an apple and two oranges in every square meter. Imagine that there are an infinite amount of square meters.

You therefore have an infinite amount of oranges and an infinite amountr of apples. But you know that there is not 1 apple in any given area and 1 orange in the same given area.

You are treating infinity as if it was an undefined amount, essentially a number. Infinity is not a number.

no it's not. But infinity over infinity gives you a result of 1. Infinity/finite gives you infinity, finite/infinity gives you 0.

The means of measurement to which I refer Cyclone, are not yet available to science. Unless of course, you know of a method of transmitting and receiving signals that travel many many times faster than light.

Incidently, please lighten up a little, your patronising manner is not really necessary, especially on a subject that top physicists and mathematicians have yet to agree. And I'm so sorry if the nature of the universe is too piddling a little matter for you, taxing your patience as it does, trying to explain it all to we lesser humans.

How stupid of me not to realise that there are many different infinities!
I posed this question as a little invitation for forumers to share thoughts and imaginings - in this hypothesis, imaginings that are possible if not provable.
No need for heavy reasoning, just thought it might be - dare I say it? - Fun.

I was having fun, sorry if you're getting upset about it.
I believe that most scientist have accepted that the size of the universe has been fairly accurately determined and most of them understand the means of measuring it.
It doesn't involve any signals travelling faster than light, just the measurement of signals which already exist, makes it a lot easier that way.

If you want to talk about an infinite space where everything has happened/will happen/is happening then have a look at brane theory. The idea of an infinite number of universes nestled within each other like layers in an onion, that one is much more plausible than an individual universe being infinite.

oh, it's oh so clear now.

If I ever write a paper on the Universe, I'll be citing the Sheffield Forum as a reference fo' shizzle. NOT.

An ant has no idea what goes on outside it's anthill, I think we're the same.

it's beyond our comprehension.

if you're interested in the concept of infinity though, I STRONGLY suggest you check out the infinite monkey theorem entry in wikipedia. After all, it is a cool theory.

oh and incidently, a friend of mine once told me he thought about the universe one night and started crying.

beware.

no it's not. But infinity over infinity gives you a result of 1. Infinity/finite gives you infinity, finite/infinity gives you 0.

You can only do mathematical operations on numbers. Infinity is a privative, not a number.

Go back to the 2d ants on a balloon surface. They can crawl around forever, but the surface area of the balloon is finite and measurable despite that.

Yes, but when talking about the extent of the universe is unbounded in nth dimensions, it makes no sense to say "it is x lightyears in diameter". That was my point

My point was, what you said it true, but the the purposes of ordinary living here on earth, we don't need to care whether it is or not.

Since most people are laymen and not cosmologists - amateur or otherwise - that means to all intents and purposes, as far as they're concerned, it's a load of fetid dingo's kidneys. :hihi:

k furry muff, follow you there, but personally i reckon we shud all care - people in general are stuck in a newtonian world/universe view, which is inaccurate

i'm all for a world of people with expanded minds

people like that tend not to get involved in wars etc and think forward to how we can improve ourselves as a whole rather than just accepting a partial world view and the status quo

yeah i know i'm a dreamer, but it's my dream and i'll dream it all i like!!!

:thumbsup:

oh and incidently, a friend of mine once told me he thought about the universe one night and started crying.

beware.

dunt tek that much to set me off on occasion - i thought about the world once quite a few years ago and started crying

Tachyon particles can (and do - theoretically) exist "out of time":).

now ur talkin my language ...

particles/strings that blip in and out of spacetime, making up what we perceive as "matter"

yeah

for me that's similar to this analogy:

imagine a 2D world, a flat plane - now if a 3D person cud place and then remove their fingertip on that flat plane from what that 3D person wud see as "above", inhabitants of the 2D plane would see a circular thing "appear" and then "disappear"

[QUOTE=Cyclone]
I was having fun,
-------------- Yeh, right Cyclone----

sorry if you're getting upset about it.
-------------- I cried all night.

I believe that most scientist have accepted that the size of the universe has been fairly accurately determined and most of them understand the means of measuring it.
--------------------Oh really? Which scientists are these Cyclone?

(As for you Richard,I said that I didn't 'trust' the maths - not that I didn't 'understand' them, as DICK implied by reminding me that maths are 'merely logic'.) Supertyke.

It doesn't involve any signals travelling faster than light, just the measurement of signals which already exist, makes it a lot easier that way. QUOTE]
Telemetry has come a long way since I was being taught in the 80s.
But I'd be really interested to hear about a means of measurement that has no need to establish a 'target' point from which to measure.
We know about the measuring of 'background radiation' - this goes some way towards explaining the 'big bang' and the 'expanding universe' theories.
But theories are all that they remain.
We haven't a clue whether these phenomena were relatively 'local' events or if several or even several billion 'big bangs occurred somewhere - sometime..

Cepheids and super novae combined with Hubbles law give reliable measurements in space but you have to be able to SEE these phenomena before you can calculate their distance.
We can only 'see' galaxies a max of about 10 -15 billion light years away, so if the 'known' universe is 156 billion light years across, it would seem that a stronger pair of specs might be needed. Red shift measurements are limited by similar constraints, the spectral sensitivity of our most advanced equipment is inadequate over these distances.

In my opinion, (I.M.O. for the sophisticates) we will never establish the size of outer space and we will just have to accept that - guess what? - We don't have all the answers.

Are you professing to read my mind and tell me that I wasn't having fun?
You seemed upset. If you cried all night though, you're probably taking it all a bit too seriously.
Lots of them, hold on i'll get you a few links.
Theories are all anything ever remains. Theory is a strong as scientific consensus ever gets. Hypothesis is the stage that comes before when it's more of a suggestion, theory means that it's widely accepted as being an accurate model.

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/971124x.html
The opinion from NASA. I guess they must have at least a couple of scientists working for them.
http://en.wikipedia.org/wiki/Universe
Wikipaedia - Editable by the masses, so some scientists must have seen the article.
http://news.bbc.co.uk/1/hi/sci/tech/3753115.stm
The BBCs take on things.

One thing that google links seem to agree on is that the universe is most definitely finite.

QUOTE [SUPERTYKE]
In my opinion, (I.M.O. for the sophisticates) we will never establish the size of outer space and we will just have to accept that - guess what? - We don't have all the answers.[/QUOTE]

We don't have all the answers
SF doesn't have all the answers? Controversial one that.

SF doesn't have all the answers? Controversial one that.

It really is B.J.
But could I be wrong for assuming that there might just be a couple of things we have still to learn about the universe???
And that, a 'theory' when applied to such a monumental mystery as the universe, may be open to a bit more interpretation than most theories?

Seriously, have you ever tried to imagine 'light speed'? And then a 'light year' - almost 6 million million miles in one year! And then that the 'known' universe is 156 billion light years across!! My V.W. would be a while getting me there!!
I don't find it at all difficult to accept that we are going to be hard pressed to come up with accurate answers, in some fields, at these distances.
I don't find it too difficult to imagine that this poky lil' planet might be just more dust for the celestial vac, well before we are near to understanding a fraction of the mysteries of the 'out there'!!

I think it's safe to admit that NO-ONE knows everything, unless you have papers after papers written by yourself. However, it is fun just to postulate ideas, and concepts. Afterall, it's only a mere exercise to your brain. Nothing more. Not something for the ego. Anyone can pick up a concept and further analyse it themselves.

I don't understand why others think to do this, means that one is being an egotist.

Actually, I didn't quite understand the question asked by the OP. As it's neither here nor there. However, when an average person like me hear the term 'infinity', it conjures up topics related to either mathematics, or the universe.

It's funny how we've swerved off into different wavelengths here...

imagine a 2D world, a flat plane - now if a 3D person cud place and then remove their fingertip on that flat plane from what that 3D person wud see as "above", inhabitants of the 2D plane would see a circular thing "appear" and then "disappear"

Never thought of it like that:thumbsup:

-----Not something for the ego.
I don't understand why others think to do this, means that one is being an egotist.

Actually, I didn't quite understand the question asked by the OP. As it's neither here nor there.
It's funny how we've swerved off into different wavelengths here...
================================================== =======
It seems that infinity itself is neither 'here nor there', Bago.

It also seems that the consensus has it that the universe definitely is bounded - if this assertion - accompanied by 'the maths to prove it' - doesn't smack of opinionated ego to you - fair enough - .

And of course, my point all along has been that, 'it's fun to postulate'.
So that, people inferring that I can't follow the maths tends to irritate, and also to deter others, who might also lack degrees in maths, from joining in.

I must admit that I was gobsmacked by the number of people who come across as being quite certain of the nature of infinity. Almost saying that there is absolutely no doubt about it having limits.
Where is the 'fun', for others, in that?

If you need any further clarification on the meaning of the O.P. Bago, please don't hesitate to ask.

The universe isn't infinate.

It is to us, three score years and ten!!!

But infinity over infinity gives you a result of 1.

Sorry, my example explains why that is not the case, there is another below.

Infinity/finite gives you infinity

True.

finite/infinity gives you 0.

Well, it gives you an infinitesimal, which is a number infinitely close to zero, but not zero.

To further explain how infinity can not be used as a number, note the following infinite series:-

2*1*2*3*4*5*6*7*.... = infinity (equation 1)

And another.

1*2*3*4*5*6*7*...=infinity (equation 2)

Now divide equation 1 by 2.

2*1*2*3*.../1*2*3*= 2 (because the factors cancel out).

Also, for interest, you can have infinite series that sum to a finite amount, these are called convergent series.

(1/2)+(1/4)+(1/8 )+(1/16)+(1/32)+...+(1/2^n)+... = 2

Also, you can have divergent series.

(1/1)+(1/2)+(1/3)+...+(1/n)+...=infinity

I love the fact that an infinite sum will not always sum to infinity.

I love the fact that an infinite sum will not always sum to infinity.

The problem with infinity, is that it isn't a number (as such).

Which is why you get odd mathemetical results when using it:).

The problem with infinity, is that it isn't a number (as such).

Which is why you get odd mathemetical results when using it:).


When a mathematician says "sums to infinity," he knows that it's just a shorthand way of saying "you can make the total as big as you want, without any upper limit, just by adding more and more terms."

When a layman hears "sums to infinity," he thinks it means "this series has a specific total, which is the number 'infinity.' "

That's the reason why all of this confusion and kerfuffle arises.

However much maths might appear to answer the question, they don't and probably can't.
The best astro physicists admit that beyond the 'horizon' of our 'known' universe, (28 billion light years in diameter) it's anyones guess; and that our 'visible' universe could be a tiny fraction of the 'whole' universe.
Or even one of many that exist beyond the edge of our own.

Either way, however many universes there are, the chances are that there are many variations of genetic data - and the forces that generate adaptive developement.
ie - size of planet - gravity - composition of atmosphere - geology etc etc. So there must be some seriously strange stuff running about out there.

Some say that because there are so many solar systems and so many planets in those systems, there must be life - some more advanced than us.
I agree with that but not that this necessarily means that we have been visited by any of them.
When you think that, at the speed of light, it would take two million years to get to our nearest galaxy - the odds of us being discovered amongst all those tiny points of light are - astronomical!
But it may have happened at some time.

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

Fermis paradox.

Interesting Cyclone.
I tend towards the theory that life is very rare, but that the numbers of possible planets that could support life are so vast, that life still must be abundant throughout the universe.

We can assume that these life forms will be at varying states of development. Some hardly out of the slime and some, - though possibly fewer, - that have overcome the urge to destroy each other and have continued to evolve.

These are logical reasons why there would be fewer civilisations advanced enough to set out to colonise more planets. (As, distances will always be mega problems to overcome, regardless of tecnological expertise.) Requiring journeys in craft designed to support life for thousands - millions of years.

And anyway, a civilisation with the ability to resist self destructive primal urges, would probably also curb its desire to proliferate, - having found that the genetic imperative, if uncontrolled, is the road to ultimate destruction.

It doesn't surprise me that life goes unrecorded in the universe, for life must be propelled by fairly uniform prerequisites wherever it evolves. And the possibility must exist that most life forms will be prone to the corruptable and ultmately destructive effects of 'power'.

We have technology sufficiently sensitive to detect the sort of radio emissions we've been chucking out in all directions for the last 100 years over a pretty large distance.
Any species that made it to the stage of the industrial revolution would start generating radio noise soon afterwards.
Any sufficiently advanced species would start doing things that would be immediately visible to anyone looking. Things like dyson spheres for example.

I'm not saying I have the answer, but fermi's paradox does make you think.

The prospect of receiving transmissions from other planets is extremely unlikely Cyclone.
Massive power outputs are needed just to send signals across the planet. Radio signals do decay with distance - they are reflected, bounced, absorbed interfered with by solar and galactic noise and presumably at the end of all this would have another atmosphere to penetrate before being picked up.

To receive a radio signal from space needs some incredibly sensitive equipment, not to mention a massive dish or even an array of many dishes. These need to be precisely focussed on a relatively small area.
To usefully 'explore' space with any thoruoghness, on every conceivable waveband at every frequency would take - a long time!!

If a transmission was picked up the chances are that it would be so weak and contaminated that neither human nor alien would recognise it.

A few years ago I was reading about a team of scientists who are searching for these 'alien transmissions'. The physics prof at Maryland uni reckoned that if someone hid a pea here on earth and you were sent to find it, with only the knowledge that it was on the planet - in the sea - underground - in a tree etc, you would have a better chance of finding it than of locating an extra terrestial radio source. (Other than natural ones.)

If an intelligent planet was halfway between us and the extremes of our galaxy, and could muster such a massive transmission, it would take over ten million years for the signal to reach us. Of course the planet could be nearer, say a million light years away, in which case it would take only one million years to reach us.
'Immediately visible' - come on Cyclone - Jupiter is immediately visible!
For most other things, a great deal of painstaking drudgery is required often resulting in zilch. The visible 'horizon' for the very best optics is tiny in terms of space exploration. Not a lot better for radio astronomy.

Iimpartiality?

Ok. Give me the 'Speed of Dark' in its unit. lol.
I will give u a nobel Prize if you can define it ! :loopy: :P

'Speed of light' is "c", and it has a unit, and it is used in many equations and theories.

the Speed of dark is the inverse of the speed light
mins x. Where x =speed of light -existing light.