Boards.ie uses cookies. By continuing to browse this site you are agreeing to our use of cookies. Click here to find out more x
Post Reply  
 
 
Thread Tools Search this Thread
19-04-2018, 12:42   #61
Four Phucs Ache
Registered User
 
Four Phucs Ache's Avatar
 
Join Date: Oct 2016
Posts: 919
It blows my mind galaxies we see light years away are exactly that. Snapshots in time millions of years ago.

Civilizations and intelligence could have existed and wiped out from a meteor or dying sun and we will never know.
Four Phucs Ache is offline  
(2) thanks from:
Advertisement
19-04-2018, 12:44   #62
lawred2
Registered User
 
Join Date: Dec 2009
Posts: 15,289
Quote:
Originally Posted by JupiterKid View Post
It is indeed OP. That’s why I’ve had an interest in astronomy since I was about 17.

Just look at this close up image of the atmosphere of the planet Jupiter, taken by the orbiting Juno probe. Surreal!!

like something by Edvard Munch
lawred2 is offline  
19-04-2018, 12:46   #63
lawred2
Registered User
 
Join Date: Dec 2009
Posts: 15,289
Quote:
Originally Posted by Kermit.de.frog View Post
If the universe is expanding than what is it expanding in to?
Uranus
lawred2 is offline  
19-04-2018, 13:20   #64
ThunderCat
Registered User
 
ThunderCat's Avatar
 
Join Date: Sep 2008
Posts: 1,319
Quote:
Originally Posted by 10000maniacs View Post
Intelligent life on other worlds is not inevitable. After 12 billion years there should be billions of unmanned probes randomly traversing the universe if intelligent life is inevitable.
Why have none ever crashed into the Moon or Mars.
Even we have half a dozen floating around in space, a few have already left our solar system. Multiply that by 6 sextillion and some should have come our way after 12 billion years.


This is easily the best thing I've read on exactly this question. Give it a go:


https://waitbutwhy.com/2014/05/fermi-paradox.html


My own personal opinion is that we are currently too primitive to detect intelligent life anywhere else. Taking the analogy that there are more stars in the universe than grains of sand on every beach on Earth, we have yet to visit the nearest grain of sand to us, which in this case would be our nearest star. And we are absolutely nowhere near achieving this either so we really are not as advanced as we think we are. We have barely sent a probe to the edge of our solar system. Speaking of which if we represent the size of our solar system as being a one euro coin then our own galaxy (one of hundreds of billions of galaxies) is the size of North America. And we have barely sent a probe to the edge of the euro coin. Think about that.
That said we are making strides and I do believe we will find signs of life in our galaxy in the coming decades, not through alien signals or alien probes or anything like that but from our advanced telescopes mapping the atmospheres of exoplanets in an attempt to detect elements in the atmosphere that do not naturally occur. Carbon emissions here in our atmosphere for example.


As for what the Universe is expanding into, my understanding is that it isn't expanding into anything as the Universe is the creation of space and time itself and those things exist within the universe and not outside it. The expansion of the universe is really more the stretching of spacetime. It is more a stretching than an expansion. Think of it as the stretching of dough with the galaxies being raisins and also stretching with it rather than more dough being constantly added and the raisins remaining static near the centre of the dough. We know this to be the case as the galaxies are moving away from each other due to the stretching of spacetime rather than the other scenario people have in their heads whereby the galaxies remain static but the universe keeps expanding.
ThunderCat is offline  
19-04-2018, 13:47   #65
 
Join Date: Jun 2010
Posts: 7,310
Quote:
Originally Posted by ThunderCat View Post
Makes for interesting reading, especially an interesting take on what a discovery of life on Mars would mean for us.

Seems a lot of this is nearly more philosophy than science though doesn't it?
wexie is offline  
Advertisement
19-04-2018, 14:05   #66
Hector Savage
Registered User
 
Hector Savage's Avatar
 
Join Date: May 2017
Posts: 5,195
Quote:
Originally Posted by valoren View Post
Agreed.

A photon of light travels at just under 300 million metres per second in a vacuum and it would take that photon 100,000 years to traverse our Milky Way galaxy alone.

Closer to home in our own solar system, Pluto orbits the Sun at an average distance of 3.7 billions miles.

Driving at 65 mph non-stop, you would cross continental USA in one week. Taking a 'direct' drive at the same speed, you'd reach Pluto in, give or take a decade or two, 6,293 years. If you instead chose to go by Boeing 777 at it's maximum speed of 590 mph, if you started the trip back in 1338 AD, 680 years ago, you'd reach Pluto in the next day or two.
Yep!
Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.


Hector Savage is offline  
Thanks from:
19-04-2018, 21:00   #67
10000maniacs
Registered User
 
10000maniacs's Avatar
 
Join Date: May 2004
Posts: 2,214
Quote:
Originally Posted by H3llR4iser View Post
It's actually very simple - the vast majority of people can't appreciate the sheer scale of just our galaxy, let alone the Universe.

Let's put it this way - Earth's oceans are brimming with fish. We know it, we've seen them and...came up with delicious recipes using them

But let's say there's a guy who has never seen a fish; Just heard stories about these creatures. He goes to the coast and takes a look for himself by scooping up a drinking glass of water from the sea. There are no fish in it.

We, as a species and civilization, are the guy staring at a glass of sea water with no fish in it - would it be reasonable to assume the ocean to be a barren expanse based on that observation?

(I *might* have lifted that example out of Neil DeGrasse Tyson's "Star Talk" podcast!)
To use your analogy with my hypothesis if I may, if your guy who has never seen a fish places a glass ball in a fixed position in the sea, eventually a fish will crash into the glass ball.
10000maniacs is offline  
19-04-2018, 21:24   #68
OneOfThem Stumbled
Registered User
 
Join Date: Apr 2011
Posts: 911
Quote:
Originally Posted by ThunderCat View Post
As for what the Universe is expanding into, my understanding is that it isn't expanding into anything as the Universe is the creation of space and time itself and those things exist within the universe and not outside it. The expansion of the universe is really more the stretching of spacetime. It is more a stretching than an expansion.
If the universe is the extent of the laws of physics, how can things happen without the existence of time? As far as I'm aware, conventional wisdom says it can't (depending on how you define "it")! As such nothing could exist before the big bang, because there wasn't a time within which for anything to exist, and as such the big bang occurring when it did makes sense, as there was no time in which it could occur before there was a time for it to occur in.

Aaah. And it still makes no sense as something can't come from nothing, much less everything! And where did all the energy come from in the first place? Some people say that there are many universes, like bubbles in a river - and while this idea is interesting, it is also alarming. Are these bubbles popping out of existence? Also, while it may explain where the "bubble" came from, an explanation for everything else (the "river") would still be required.

We know so little. We are like ancient Greeks with a little bit of knowledge - capacities in the sciences and the arts, but outside of our own little world; the underpinnings of everything and the dark universe around us are obscure, unreachable and unknown.
OneOfThem Stumbled is offline  
(2) thanks from:
19-04-2018, 21:37   #69
 
Join Date: Jun 2010
Posts: 7,310
Quote:
Originally Posted by OneOfThem Stumbled View Post
If the universe is the extent of the laws of physics, how can things happen without the existence of time? As far as I'm aware, conventional wisdom says it can't (depending on how you define "it")! As such nothing could exist before the big bang, because there wasn't a time within which for anything to exist, and as such the big bang occurring when it did makes sense, as there was no time in which it could occur before there was a time for it to occur in.

Aaah. And it still makes no sense as something can't come from nothing, much less everything! And where did all the energy come from in the first place? Some people say that there are many universes, like bubbles in a river - and while this idea is interesting, it is also alarming. Are these bubbles popping out of existence? Also, while it may explain where the "bubble" came from, an explanation for everything else (the "river") would still be required.

We know so little. We are like ancient Greeks with a little bit of knowledge - capacities in the sciences and the arts, but outside of our own little world; the underpinnings of everything and the dark universe around us are obscure, unreachable and unknown.
Can't for the life of me remember where I read it but apparently (if I remember correctly) physics as we know it is pretty accurate right up till just after the BigBang. During and before the big bang it all gets a bit screwy. Partly no doubt, because of some of the things you mentioned there.
wexie is offline  
Advertisement
19-04-2018, 22:21   #70
Four Phucs Ache
Registered User
 
Four Phucs Ache's Avatar
 
Join Date: Oct 2016
Posts: 919
From what I understand just after the big bang as in millionths of a second, all that existed was pure energy that expanded instantly to infinity.

What I don't understand and probably never will is how does matter currently exist if dark matter doesn't?

If dark/anti matter neutrons collide with positive neutrons they destroy each other so just moments after the big bang with everything nice and tight they should have canceled each other out?

Feckin brain is melted now.
Four Phucs Ache is offline  
19-04-2018, 22:29   #71
JupiterKid
Registered User
 
JupiterKid's Avatar
 
Join Date: Dec 2004
Posts: 7,664
The Andromeda Galaxy, about 2 million light years away. The closest large spiral galaxy to our own, the Milky Way.



Astronomers think that our galaxy and Andromeda will merge into a giant elliptical in less than a billion years.

Last edited by JupiterKid; 19-04-2018 at 22:52.
JupiterKid is offline  
19-04-2018, 22:40   #72
Fourier
Registered User
 
Join Date: Jan 2012
Posts: 10,199
To answer a few questions on the thread.

The Big Bang is not the beginning of the universe, just the earliest point we can reconstruct from observations. The universe could have existed for trillions of years prior to it, or five minutes. We don't know.

As for why matter and antimatter didn't cancel out, the full explanation is too complicated for a forum post, but essentially the laws of physics are not symmetrical between matter and antimatter. On average, over billions of particle collisions, slightly more matter is produced than antimatter, so they don't perfectly cancel out.

Last edited by Fourier; 20-04-2018 at 11:58.
Fourier is online now  
19-04-2018, 22:56   #73
JupiterKid
Registered User
 
JupiterKid's Avatar
 
Join Date: Dec 2004
Posts: 7,664
The ringed gas giant planet Saturn and its largest moon, Titan, seen edge on by the Cassini probe.

Titan is the only moon in our solar system that has a substantial atmosphere and has seas of liquid ethane. The Huygens probe successfully landed on Titan in 2005.


Last edited by JupiterKid; 20-04-2018 at 01:38.
JupiterKid is offline  
19-04-2018, 22:58   #74
Giblet
Registered User
 
Giblet's Avatar
 
Join Date: Oct 2001
Posts: 11,126
Quote:
Originally Posted by 10000maniacs View Post
To use your analogy with my hypothesis if I may, if your guy who has never seen a fish places a glass ball in a fixed position in the sea, eventually a fish will crash into the glass ball.
Firstly how would you know? And secondly who says you can reach the middle, you can barely get the ball wet as it is. If you thinking probes should crash into mars because there are so many of them, then you vastly under estimate the size of the Uinverse and the Distances involved, The speed of light dictates that a civilisation would need be given a hell of a head start, and any civilisation that has such a head start, is going to know how to hide from us idiots.
Giblet is offline  
20-04-2018, 00:10   #75
10000maniacs
Registered User
 
10000maniacs's Avatar
 
Join Date: May 2004
Posts: 2,214
Quote:
Originally Posted by Giblet View Post
Firstly how would you know? And secondly who says you can reach the middle, you can barely get the ball wet as it is. If you thinking probes should crash into mars because there are so many of them, then you vastly under estimate the size of the Uinverse and the Distances involved, The speed of light dictates that a civilisation would need be given a hell of a head start, and any civilisation that has such a head start, is going to know how to hide from us idiots.
You say what about the size of the universe?
I say what about the amount of time since the first intelligent civilization was formed to the last, maybe 10 billion years if life is inevitable?. And what about the gargantuan amount of civilisations formed since the first one if intelligent life is inevitable?
What about the 100,000 potential intelligent civilisations formed in our galaxy if intelligent life is inevitable? Where are they? Where are their radio waves, where are their probes?
I personally think we are a bizarre freak of chemistry that only happened once.
10000maniacs is offline  
Post Reply

Quick Reply
Message:
Remove Text Formatting
Bold
Italic
Underline

Insert Image
Wrap [QUOTE] tags around selected text
 
Decrease Size
Increase Size
Please sign up or log in to join the discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search



Share Tweet