life out there?
Discussion
I think something else stands a good chance of getting us.
http://www.passc.net/EarthImpactDatabase/Worldmap....
Bet we are not the only ones with bits whizzing around a solar system.
http://www.passc.net/EarthImpactDatabase/Worldmap....
Bet we are not the only ones with bits whizzing around a solar system.
Simpo Two said:
On what basis is that? How many advanced species did the theorist study? There is only one as far as I know and it's still going.
True - but in terms of life on earth - we are still but a blip. Humans have been around for only 200,000 years - that's no time at all. To trumpet that fact we are "still going" - when in fact we have barely just come down from the trees (in geological terms) seems a little premature.
Our technology may help us prolong our existence on (or even off) the earth - but when you examine the fate of most species on earth - the odds do seem to be stacked against us. Extinction would seem to be the natural order of things and most individual species are nothing more than an evolutionary flash in the pan.
Moonhawk said:
True - but in terms of life on earth - we are still but a blip. Humans have been around for only 200,000 years - that's no time at all.
What does that have to do with wiping ourselves out?Moonhawk said:
To trumpet that fact we are "still going" - when in fact we have barely just come down from the trees (in geological terms) seems a little premature.
So are we a young civilisation just starting or an old one about to destroy itself? Either way, we as a single species have achieved more than all the others put together.Moonhawk said:
Our technology may help us prolong our existence on (or even off) the earth - but when you examine the fate of most species on earth - the odds do seem to be stacked against us. Extinction would seem to be the natural order of things and most individual species are nothing more than an evolutionary flash in the pan.
But as you say, we have technology. None of the extinct species did. They were made extinct either by significant climate change (far greater than anything we have done), or predation. Neither of those affects H. sapiens, at least not yet. But if you have an idea how to kill every single member of the species, I'd be interested to know.I think you're taking rather a hand-wringing 'oh my god it's all too good to last' approach without putting any logical thought in
I prefer to look at it this way, life will continue unless it is a real major event, we may not be part of the long term future.
One planet killer curtesy of Jupiter and we are all toast. Which raises the question, knowing we have had a impact that would give us a bad day in the past, how often does this happen elsewhere.
One planet killer curtesy of Jupiter and we are all toast. Which raises the question, knowing we have had a impact that would give us a bad day in the past, how often does this happen elsewhere.
Simpo Two said:
Moonhawk said:
True - but in terms of life on earth - we are still but a blip. Humans have been around for only 200,000 years - that's no time at all.
What does that have to do with wiping ourselves out?Moonhawk said:
To trumpet that fact we are "still going" - when in fact we have barely just come down from the trees (in geological terms) seems a little premature.
So are we a young civilisation just starting or an old one about to destroy itself? Either way, we as a single species have achieved more than all the others put together.Moonhawk said:
Our technology may help us prolong our existence on (or even off) the earth - but when you examine the fate of most species on earth - the odds do seem to be stacked against us. Extinction would seem to be the natural order of things and most individual species are nothing more than an evolutionary flash in the pan.
But as you say, we have technology. None of the extinct species did. They were made extinct either by significant climate change (far greater than anything we have done), or predation. Neither of those affects H. sapiens, at least not yet. But if you have an idea how to kill every single member of the species, I'd be interested to know.I think you're taking rather a hand-wringing 'oh my god it's all too good to last' approach without putting any logical thought in
'Filters' is the often used term.
https://en.wikipedia.org/wiki/Fermi_paradox
For the record, if push comes to shove I stand with Moonhawk's thinking rather than yours!
Simpo Two said:
But as you say, we have technology. None of the extinct species did. They were made extinct either by significant climate change (far greater than anything we have done), or predation. Neither of those affects H. sapiens, at least not yet. But if you have an idea how to kill every single member of the species, I'd be interested to know.
I think you're taking rather a hand-wringing 'oh my god it's all too good to last' approach without putting any logical thought in
None of the extinct species on Earth did... Elsewhere who knows? I think you're taking rather a hand-wringing 'oh my god it's all too good to last' approach without putting any logical thought in
I have the "idea" you're interested in. Entropy. The universe is flat and will keep expanding so it will end cold and dark. All life within it will extinguished, with all suns dead. There will not only be no life and no one to observe it, even if they could stare up at the sky they would see only a darkness, and there will be no trace anyone was had ever existed, forever.
Matter is about ~1% of the mass of the universe, we are cosmic pollution, like the puff of smoke forming patterns above an extinguished candle flame, and it is only a matter of time before everything, good and bad, is destroyed.
Enjoy it whilst it lasts gentleman. We live in a golden age and if there is one thing you can take to the bank, it is that all of this is going to end.
Skodasupercar said:
This is often referred to when people talk about the Fermi paradox.
'Filters' is the often used term.
https://en.wikipedia.org/wiki/Fermi_paradox
Nope, that's taking about the probability of other life. The subject it led on to was whether or not H. sapiens is going to wipe itself out. 'Filters' is the often used term.
https://en.wikipedia.org/wiki/Fermi_paradox
Prof Prolapse is right that we cannot last for ever, but that's not the as wiping ourselves out.
ash73 said:
Major new Kepler planet discoveries to be announced tomorrow here
Here's the NASA Audio link: http://www.nasa.gov/news/media/newsaudio/index.htm...Surprised there is no video if its going to be some kind of semi-major announcement.
5pm UK kick-off time.
I've started a thread. http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Edited by mudflaps on Thursday 23 July 17:20
Simpo Two said:
But as you say, we have technology. None of the extinct species did. They were made extinct either by significant climate change (far greater than anything we have done), or predation. Neither of those affects H. sapiens, at least not yet. But if you have an idea how to kill every single member of the species, I'd be interested to know.
Ice age? It will happen with or without the killer CO2 
TX.
OK, here's where my brain explodes. I've not been in this thread for a while and very busy to read through it all, so please bare with me.
Einstein says that nothing can travel at more than the speed of light, it's basically a speed limit. The Big Band occured ~13-14 billion years ago (can't remember which, but irrelevant for my question). So, with that in mind surely the Universe can only be 26-28 billian Light years in Diameter.
But a couple of posts earlier (both on page 3 or 4 I think, stated that the universe is infinite (my childhood understanding) and another said something like 91 billian light years in diameter?
I don't get how that's possible with Einstein's E-MC2?
Apologies if this is a real duffer's question!
Einstein says that nothing can travel at more than the speed of light, it's basically a speed limit. The Big Band occured ~13-14 billion years ago (can't remember which, but irrelevant for my question). So, with that in mind surely the Universe can only be 26-28 billian Light years in Diameter.
But a couple of posts earlier (both on page 3 or 4 I think, stated that the universe is infinite (my childhood understanding) and another said something like 91 billian light years in diameter?
I don't get how that's possible with Einstein's E-MC2?
Apologies if this is a real duffer's question!
The big bang occurred 'everywhere' not just in our neck of the woods so yes it happened 13-14 billion years ago and we are restricted to viewing that area of expansion.
My best analogy. If the big bang happened in London and the speed of light was 0.0000000001 mph then after say 13b years our 'bubble' would be up to say Birmingham and down to say mid-france. However at the same time as the big bang was happening in London it was also happening in Glasgow and they have a completely different but similar sized 'bubble' stretching 26b light years too.
That's why nobody knows the actual size of the whole Universe - just our 'bubble'.
It's a head f
k I know.
Here's Space.com's explanation.
As technology has evolved, astronomers are able to look back in time to the moments just after the Big Bang. This might seem to imply that the entire universe lies within our view. But the size of the universe depends on a number of things, including its shape and expansion. Just how big is the universe? The truth is, scientists can't put a number on it.
The observable universe
Astronomers have measured the age of the universe to be approximately 13.8 billion years old. Because of the connection between distance and the speed of light, this means they can look at a region of space that lies 13.8 billion light-years away. Like a ship in the empty ocean, astronomers on Earth can turn their telescopes to peer 13.8 billion light-years in every direction, which puts Earth inside of an observable sphere with a radius of 13.8 billion light-years. The word "observable" is key; the sphere limits what scientists can see but not what is there.
But though the sphere appears almost 28 billion light-years in diameter, it is far larger. Scientists know that the universe is expanding. Thus, while scientists might see a spot that lay 13.8 billion light-years from Earth at the time of the Big Bang, the universe has continued to expand over its lifetime. Today, that same spot is 46 billion light-years away, making the diameter of the observable universe a sphere around 92 billion light-years.
Centering a sphere on Earth's location in space might seem to put mankind in the center of the universe. However, like that same ship in the ocean, we cannot tell where we lie in the enormous span of the universe. Just because we cannot see land does not mean we are in the center of the ocean; just because we cannot see the edge of the universe does not mean we lie in the center of the universe.
The shape of the universe
The size of the universe depends a great deal on its shape. Scientists have predicted the possibility that the universe might be closed like a sphere, infinite and negatively curved like a saddle, or flat and infinite.
A finite universe has a finite size that can be measured; this would be the case in a closed spherical universe. But an infinite universe has no size by definition.
According to NASA, scientists know that the universe is flat with only about a 0.4 percent margin of error (as of 2013). A flat universe is an infinite universe; thus the size of the universe is infinite.
My best analogy. If the big bang happened in London and the speed of light was 0.0000000001 mph then after say 13b years our 'bubble' would be up to say Birmingham and down to say mid-france. However at the same time as the big bang was happening in London it was also happening in Glasgow and they have a completely different but similar sized 'bubble' stretching 26b light years too.
That's why nobody knows the actual size of the whole Universe - just our 'bubble'.
It's a head f
k I know.Here's Space.com's explanation.
As technology has evolved, astronomers are able to look back in time to the moments just after the Big Bang. This might seem to imply that the entire universe lies within our view. But the size of the universe depends on a number of things, including its shape and expansion. Just how big is the universe? The truth is, scientists can't put a number on it.
The observable universe
Astronomers have measured the age of the universe to be approximately 13.8 billion years old. Because of the connection between distance and the speed of light, this means they can look at a region of space that lies 13.8 billion light-years away. Like a ship in the empty ocean, astronomers on Earth can turn their telescopes to peer 13.8 billion light-years in every direction, which puts Earth inside of an observable sphere with a radius of 13.8 billion light-years. The word "observable" is key; the sphere limits what scientists can see but not what is there.
But though the sphere appears almost 28 billion light-years in diameter, it is far larger. Scientists know that the universe is expanding. Thus, while scientists might see a spot that lay 13.8 billion light-years from Earth at the time of the Big Bang, the universe has continued to expand over its lifetime. Today, that same spot is 46 billion light-years away, making the diameter of the observable universe a sphere around 92 billion light-years.
Centering a sphere on Earth's location in space might seem to put mankind in the center of the universe. However, like that same ship in the ocean, we cannot tell where we lie in the enormous span of the universe. Just because we cannot see land does not mean we are in the center of the ocean; just because we cannot see the edge of the universe does not mean we lie in the center of the universe.
The shape of the universe
The size of the universe depends a great deal on its shape. Scientists have predicted the possibility that the universe might be closed like a sphere, infinite and negatively curved like a saddle, or flat and infinite.
A finite universe has a finite size that can be measured; this would be the case in a closed spherical universe. But an infinite universe has no size by definition.
According to NASA, scientists know that the universe is flat with only about a 0.4 percent margin of error (as of 2013). A flat universe is an infinite universe; thus the size of the universe is infinite.
AshVX220 said:
Einstein says that nothing can travel at more than the speed of light, it's basically a speed limit. The Big Band occured ~13-14 billion years ago (can't remember which, but irrelevant for my question). So, with that in mind surely the Universe can only be 26-28 billian Light years in Diameter.
Inflation deals with that.Whilst it's true that nothing with mass can travel through spacetime - there is no restriction on spacetime itself expanding faster than the speed of light (and thereby carrying the mass with it).
AshVX220 said:
OK, here's where my brain explodes. I've not been in this thread for a while and very busy to read through it all, so please bare with me.
Einstein says that nothing can travel at more than the speed of light, it's basically a speed limit. The Big Band occured ~13-14 billion years ago (can't remember which, but irrelevant for my question). So, with that in mind surely the Universe can only be 26-28 billian Light years in Diameter.
But a couple of posts earlier (both on page 3 or 4 I think, stated that the universe is infinite (my childhood understanding) and another said something like 91 billian light years in diameter?
I don't get how that's possible with Einstein's E-MC2?
Apologies if this is a real duffer's question!
I don't think there are daft questions. I read this stuff to remind me I'm not as smart as I think I am. Einstein says that nothing can travel at more than the speed of light, it's basically a speed limit. The Big Band occured ~13-14 billion years ago (can't remember which, but irrelevant for my question). So, with that in mind surely the Universe can only be 26-28 billian Light years in Diameter.
But a couple of posts earlier (both on page 3 or 4 I think, stated that the universe is infinite (my childhood understanding) and another said something like 91 billian light years in diameter?
I don't get how that's possible with Einstein's E-MC2?
Apologies if this is a real duffer's question!
The short answer is because "space" can travel faster than light.
ETA: I see it's already been answered...
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