Astronomy & Space Exploration

MrMarcello

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Felt it deserved its own thread.

I'll start off with this...

http://news.yahoo.com/largest-structure-universe-discovered-093416167.html

Largest Structure in Universe Discovered
By Mike Wall | SPACE.com – 15 hrs ago

Astronomers have discovered the largest known structure in the universe, a clump of active galactic cores that stretches 4 billion light-years from end to end.

The structure is a large quasar group (LQG), a collection of extremely luminous galactic nuclei powered by supermassive central black holes. This particular group is so large that it challenges modern cosmological theory, researchers said.

"While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe," lead author Roger Clowes, of the University of Central Lancashire in England, said in a statement. "This is hugely exciting, not least because it runs counter to our current understanding of the scale of the universe."

Quasars are the brightest objects in the universe. For decades, astronomers have known that they tend to assemble in huge groups, some of which are more than 600 million light-years wide.

But the record-breaking quasar group, which Clowes and his team spotted in data gathered by the Sloan Digital Sky Survey, is on another scale altogether. The newfound LQC is composed of 73 quasars and spans about 1.6 billion light-years in most directions, though it is 4 billion light-years across at its widest point.

To put that mind-boggling size into perspective, the disk of the Milky Way galaxy — home of Earth's solar system — is about 100,000 light-years wide. And the Milky Way is separated from its nearest galactic neighbor, Andromeda, by about 2.5 million light-years.

The newly discovered LQC is so enormous, in fact, that theory predicts it shouldn't exist, researchers said. The quasar group appears to violate a widely accepted assumption known as the cosmological principle, which holds that the universe is essentially homogeneous when viewed at a sufficiently large scale.

Calculations suggest that structures larger than about 1.2 billion light-years should not exist, researchers said.

"Our team has been looking at similar cases which add further weight to this challenge, and we will be continuing to investigate these fascinating phenomena," Clowes said.

The new study was published today (Jan. 11) in the Monthly Notices of the Royal Astronomical Society.
 

Kraftwerker

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Felt it deserved its own thread.

I'll start off with this...

http://news.yahoo.com/largest-structure-universe-discovered-093416167.html

Largest Structure in Universe Discovered
By Mike Wall | SPACE.com – 15 hrs ago

Astronomers have discovered the largest known structure in the universe, a clump of active galactic cores that stretches 4 billion light-years from end to end.

The structure is a large quasar group (LQG), a collection of extremely luminous galactic nuclei powered by supermassive central black holes. This particular group is so large that it challenges modern cosmological theory, researchers said.

"While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe," lead author Roger Clowes, of the University of Central Lancashire in England, said in a statement. "This is hugely exciting, not least because it runs counter to our current understanding of the scale of the universe."

Quasars are the brightest objects in the universe. For decades, astronomers have known that they tend to assemble in huge groups, some of which are more than 600 million light-years wide.

But the record-breaking quasar group, which Clowes and his team spotted in data gathered by the Sloan Digital Sky Survey, is on another scale altogether. The newfound LQC is composed of 73 quasars and spans about 1.6 billion light-years in most directions, though it is 4 billion light-years across at its widest point.

To put that mind-boggling size into perspective, the disk of the Milky Way galaxy — home of Earth's solar system — is about 100,000 light-years wide. And the Milky Way is separated from its nearest galactic neighbor, Andromeda, by about 2.5 million light-years.

The newly discovered LQC is so enormous, in fact, that theory predicts it shouldn't exist, researchers said. The quasar group appears to violate a widely accepted assumption known as the cosmological principle, which holds that the universe is essentially homogeneous when viewed at a sufficiently large scale.

Calculations suggest that structures larger than about 1.2 billion light-years should not exist, researchers said.

"Our team has been looking at similar cases which add further weight to this challenge, and we will be continuing to investigate these fascinating phenomena," Clowes said.

The new study was published today (Jan. 11) in the Monthly Notices of the Royal Astronomical Society.
So it would take light 4 billion years to travel the length of it?

The universe freaks me out.
 

Liam147

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That was a fecking incredible video. Even though it's saying most of what you already know, actually 'flying' through the universe like that is amazing.

Not to derail the thread, but when he's talking about the light from Edison's bulb for example, how does that work? Because although the light won't technically stop travelling, it will get to a point where it's no longer visible. Or have I missed something there?
 

Drainy

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The software is called Celestia, it's free to download if you want to mess around with it.

You are right, he's talking about a theoretical point where the light particles have reached.
Obviously the light from the bulb will be too dim to be viewed at that distance, just like how you can't see the sun after a certain point.
 

Raoul

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Used to be in awe of the planets, stars etc. but now I'm more interested in the subatomic piece of the equation. What is the Universe made of ?
 

Gambit

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All the Stargazing shows are being shown back to back right now.
 

Pexbo

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That was incredible, the map of the universe at just 400,000 years old. Some 12,000,000,000 years ago.
 

JohnLocke

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I posted something similar to this in the newbies when I was down there, but I couldn't be bothered posting the whole thing. So I'll just scale it down a bit.

The Scale of the Solar System:

Using a size 5 football as a representation of the sun you will need to walk x meters to said planet.

Mercury - 9.4m
Venus - 17.5m
Earth - 24m
Mars - 37m


Jupiter - 126m
Saturn - 231m

Neptune - 466m
Uranus - 730m
Pluto - 960m

That's almost a km! So if the sun was the size of a football the solar system would be almost a km long. (I know that Pluto is no longer classed as a planet as well!)

http://www.exploratorium.edu/ronh/solar_system/
 

Gambit

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That was incredible, the map of the universe at just 400,000 years old. Some 12,000,000,000 years ago.
So surely our galaxy would have traveled from there. Does that mean we could be looking at the Milky way in there somewhere?
 

jojojo

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In the spirit of linksharing then, an introduction to the dawn of the universe as we know it. I know the big bang is not exactly a current event, but it's amazing just how fast ideas in astronomy, like dark matter, dark energy etc are developing right now.

 

Will Absolute

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Great days for ET hunters.

Although frustation is likely to set in when the initial excitement dies down, and we realize that identifying potentially habitable planets is all we can ever do. No observation from Earth will tell us definitively whether any of our candidate planets does harbour life.

Unless we detect radio wave or laser emissions of course. What a day that would be!
 

Count Orduck

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Travelling at the speed of light, the 4 billion light year journey would be instantaneous.

Time elapsed: 0.0000.... seconds.
Er, I'm afraid not. A light year is named that because it's how far light travels in one year (to just under 10 trillion kilometres or about 6 trillion miles).

So if you travelled at the speed of light, a 4 billion light-year journey would take you... four billion years.

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

RedLars

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Er, I'm afraid not. A light year is named that because it's how far light travels in one year (to just under 10 trillion kilometres or about 6 trillion miles).

So if you travelled at the speed of light, a 4 billion light-year journey would take you... four billion years.

http://en.wikipedia.org/wiki/Light_year
http://en.wikipedia.org/wiki/Time_dilation

And more simply explained

http://nimbleit.squarespace.com/sim...down-when-approaching-the-speed-of-light.html

Edit: To clarify, 4 billion years will have passed on earth, but no time at all will have passed for the one traveling at the speed of light. But then the theory doesn't allow for any mass traveling at the speed of light so that might be wrong anyways.
 

RK

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Er, I'm afraid not. A light year is named that because it's how far light travels in one year (to just under 10 trillion kilometres or about 6 trillion miles).

So if you travelled at the speed of light, a 4 billion light-year journey would take you... four billion years.

http://en.wikipedia.org/wiki/Light_year
Unless he's talking about length contraction. I was never the best at Special Relativity.

EDIT: Or time dilation, as RedLars has pointed out
 

Will Absolute

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Er, I'm afraid not. A light year is named that because it's how far light travels in one year (to just under 10 trillion kilometres or about 6 trillion miles).

So if you travelled at the speed of light, a 4 billion light-year journey would take you... four billion years.

http://en.wikipedia.org/wiki/Light_year
Nope. :D

An object (man or atom) travelling at the speed of light doesn't age. If we (on Earth) were to measure the time taken for a spaceship moving at the speed of light to travel 4 billion light years, we would conclude that the journey took 4 billion years. But for the crew of the spaceship, the trip takes no time at all. They're no older at journey's end than at the beginning.

No material object can travel at the speed of light, so the question is academic. But it's theoretically possible to accelerate as close to the speed of light as desired. So a journey of 4 billion light years could be accomplished in a human lifetime.

Ps. Bizarrely, for the spaceship crew, there's no journey at all. They travel zero miles in zero seconds. 'Length contraction' reduces the distance to zero. For an object travelling at the speed of light, space and time don't exist. Only here and now.
 

MichaelS

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Nope. :D

An object (man or atom) travelling at the speed of light doesn't age. If we (on Earth) were to measure the time taken for a spaceship moving at the speed of light to travel 4 billion light years, we would conclude that the journey took 4 billion years. But for the crew of the spaceship, the trip takes no time at all. They're no older at journey's end than at the beginning.

No material object can travel at the speed of light, so the question is academic. But it's theoretically possible to accelerate as close to the speed of light as desired. So a journey of 4 billion light years could be accomplished in a human lifetime.

Ps. Bizarrely, for the spaceship crew, there's no journey at all. They travel zero miles in zero seconds. 'Length contraction' reduces the distance to zero. For an object travelling at the speed of light, space and time don't exist. Only here and now.
Aren't photon's material objects?
 

JohnLocke

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Human intuition is very flawed in this subject. People feel like time is constant, but it isn't- the speed of light is the constant.

Or at least that's my very poor understanding of it :lol:
I know that the speed of light is the constant, but I think if you are travelling a distance of 4 billion light years, at the speed of light, it will still take time to get there. Observers on Earth would say that it takes 4 billion years, whereas for the traveller it may take less time.:nervous:

But it would certainly take an amount of time (a considerable amount actually), so I don't believe that it would take no time / be instantanious.

Also agree with the part that light particles travel at the speed of light but they also take a fixed amount of time to get from A to B. Regardless of where you observe it. Maybe... :nervous:
 

JohnLocke

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There's a trilogy of books, The Forever War, that deals with this same issue. But iirc the protagonist travels thousands of light years away going through black holes, and is travelling at 99.99% the speed of light.

When he comes back from his first tour of duty he has been away for two years or so, but a few decades have passed on Earth. Each time he goes away he comes back and more and more years have passed and things on Earth a very very different to what he left behind and he can't fit into their society.
 

Revan

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Er, I'm afraid not. A light year is named that because it's how far light travels in one year (to just under 10 trillion kilometres or about 6 trillion miles).

So if you travelled at the speed of light, a 4 billion light-year journey would take you... four billion years.

http://en.wikipedia.org/wiki/Light_year
As others pointed out, when you travel at the speed of light (which is theoretically impossible) there is no time and no space. For the observers, a 4 billion light year journey would take 4 billions. But for the person who is in that spaceship it would take nothing at all.

The good part is that no-one will ever travel at the speed light. But it is very arguable that we could travel with near speed of light which will make time flow slower than for observers.
 

Phurry

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The zero time concept also makes the assumption that acceleration to and braking from the speed of light would be instantaneous, that's gonna hurt.
 

Revan

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Aren't photon's material objects?
Little complicated, it's the dual nature of the light. In some cases it behaves like wave and in some others like matter. But yeah, photons are massless, that's the reason why we don't die when they hit us.
 

Liam147

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Nope. :D

An object (man or atom) travelling at the speed of light doesn't age. If we (on Earth) were to measure the time taken for a spaceship moving at the speed of light to travel 4 billion light years, we would conclude that the journey took 4 billion years. But for the crew of the spaceship, the trip takes no time at all. They're no older at journey's end than at the beginning.

No material object can travel at the speed of light, so the question is academic. But it's theoretically possible to accelerate as close to the speed of light as desired. So a journey of 4 billion light years could be accomplished in a human lifetime.

Ps. Bizarrely, for the spaceship crew, there's no journey at all. They travel zero miles in zero seconds. 'Length contraction' reduces the distance to zero. For an object travelling at the speed of light, space and time don't exist. Only here and now.
That post made me feel sad.

You cnuts are making my head hurt. Why can't time be a constant, linear thing? I cannot comprehend time as a 'dimension' or whatever.
In the spirit of linksharing then, an introduction to the dawn of the universe as we know it. I know the big bang is not exactly a current event, but it's amazing just how fast ideas in astronomy, like dark matter, dark energy etc are developing right now.

That's a good video. He's go loads of interesting stuff.


I'd like to say "I wish I knew what happened just before the big bang", but apparently, there was no time then! feck you.
 

Will Absolute

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Aren't photon's material objects?
The Universe is composed of two kinds of things - matter (material objects) and energy. A photon is an energy packet and belongs to the second category. Energy moves at the speed of light, whereas matter moves at speeds less than the speed of light.

It's difficult to convince people of the implications of the Special Theory of Relativity, because it's so counterintuitive. People (including most physics students:lol:) cling stubbornly to the constancy of time. All I can say is that theoretical physicists would agree with me.

Actually the theory is one of the most well established in science. One of the best ways of demonstrating it's truth is by looking at the behaviour of subatomic particles in particle accelerators.

A subatomic particle is a tiny bit of matter given off when larger particles collide. There are many different kinds, and some have very short lifespans - 1 millionth of a second, say.

The interesting thing is that when these particles are accelerated close to the speed of light, their lifespans greatly increase. They become the methuselahs of the subtomic world, living 2,3, 5 or even 10 millionths of a second.

Of course, from the particles point of view, they live their normal lifespan. It's simply that at speeds close to the speed of light, time slows down.
 

Revan

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That post made me feel sad.

You cnuts are making my head hurt. Why can't time be a constant, linear thing? I cannot comprehend time as a 'dimension' or whatever.
Einstein is a cnut. Before him, time was constant but he decided to mess up with our heads. But to be fair, despite looking very counter intuitive, is not that much complicated.
 

MrMarcello

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When I think of space travel and what observers see I often recall Contact and how despite witnesses viewing a few seconds as the pod dropped, the pilot's recorder taped 18 hours of static footage.

However, reading above it seems as though it might be backwards. Would time on Earth be longer than time in space or the opposite?

Scene I'm referring to begins at 1:55:xx, occurs at 2:06:xx and the report mentioning 18 hours footage begins at 2:18:xx. Granted this is a movie but I would imagine they consulted scientists during the filming.

http://www.youtube.com/watch?v=wNnAMpQxGQ4
 

MichaelS

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The Universe is composed of two kinds of things - matter (material objects) and energy. A photon is an energy packet and belongs to the second category. Energy moves at the speed of light, whereas matter moves at speeds less than the speed of light.

It's difficult to convince people of the implications of the Special Theory of Relativity, because it's so counterintuitive. People (including most physics students:lol:) cling stubbornly to the constancy of time. All I can say is that theoretical physicists would agree with me.

Actually the theory is one of the most well established in science. One of the best ways of demonstrating it's truth is by looking at the behaviour of subatomic particles in particle accelerators.

A subatomic particle is a tiny bit of matter given off when larger particles collide. There are many different kinds, and some have very short lifespans - 1 millionth of a second, say.

The interesting thing is that when these particles are accelerated close to the speed of light, their lifespans greatly increase. They become the methuselahs of the subtomic world, living 2,3, 5 or even 10 millionths of a second.

Of course, from the particles point of view, they live their normal lifespan. It's simply that at speeds close to the speed of light, time slows down.
I can't really wrap my head around energy. I just don't understand, that if photons are not material, it would mean that light is non-physical, while it it clearly is physical. Luckily there are much brighter people than I who can enlighten me.
 

Will Absolute

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When I think of space travel and what observers see I often recall Contact and how despite witnesses viewing a few seconds as the pod dropped, the pilot's recorder taped 18 hours of static footage.

However, reading above it seems as though it might be backwards. Would time on Earth be longer than time in space or the opposite?

Scene I'm referring to begins at 1:55:xx, occurs at 2:06:xx and the report mentioning 18 hours footage begins at 2:18:xx. Granted this is a movie but I would imagine they consulted scientists during the filming.

http://www.youtube.com/watch?v=wNnAMpQxGQ4
I've not seen the movie, but I looked at the bits you indicated.

If Jodie had travelled to the far side of the Galaxy and returned, through normal space, moving at close to light speed, clocks on her ship would record an 18 hour passage of time. There would be no one to greet her return of course, as about 200,000 years would have passed on Earth, and humanity would likely be extinct.

But the movie uses the idea that she travelled through a series of wormholes, which are not part of normal space, and that changes all calculations. Wormholes are as much science fiction as fact, and no one knows if they exist, or could ever be used in the way the movie describes. The theory is beyond what I properly understand anyway, which is only the basic stuff.