Life Is A Dream To Work On
How Can We See Galaxies 47 Billion Light Years Away When the Universe is Only 13 Billion Years Old?
How's your world luv's? I greet you with an open heart and mind. The net for me is one of the greatest things for my insomnia. Most of the times when I can not sleep is because my brain never shuts up or off! It has a ravaging appetite for knowledge and requires to be fed..A LOT! One site I have self prescribed is:
http://motherchi.stumbleupon.com/
It gives me an unlimited supply of web site from everywhere on any one of the unlimited amount of things that totally intrigue and fascinates me about life. This is one of the articles that popped up last night that I thought was well worth sharing.
How Can We See Galaxies 47 Billion Light Years Away When the Universe is Only 13 Billion Years Old?
Posted in: cosmology
Hubble ultra deep field This is my second post in the Just Science Week Challenge.
This 2003 paper in Physical Review Letters puts a lower limit on the size of the universe at no smaller than 46.5 billion light years in radius. If the universe is geometrically flat, that is.
In this video I made on the Hubble Deep Field, I mentioned this number and was immediately inundated with questions and comments from people screaming that that number could not possibly be correct. How can the universe be that big if the fastest anything can travel is the speed of light? The universe simply CAN’T be larger than the distance light travels during age of the universe, right?
Wrong.
It is true that the universe is 13.5 billion years old, and it is also true that nothing can travel faster than the speed of light. But it does NOT follow that the size of the universe is simply the distance light traveled in 13.5 billion years. You can’t stop there. Why?
Because the universe is expanding, and has been for 13.5 billion years.
Remember yesterday’s post? Everything in the entire universe is flying away from each other at a rate linearly proportional to its distance. That’s Hubble’s Law. The distance that light has to travel over time is continuously getting bigger and you MUST take that into account.
Technorati Tags: cosmology
Remember in my last post, we’ve established that the universe is expanding at roughly the Hubble Constant, and that number is a function of time. It matters WHEN you take your measurement of the redshifts of far away galaxies. Right now, the universe is expanding at about 71 km/sec/Mpc and is accelerating.
Here's an interesting article I found web surfing today on one of my favorite subjects.I help categorize galaxies at galazyzoo.org.
A somewhat simpler way to think of the expansion rate of the universe is that it expands at roughly the age of the universe to the 2/3 power: Age Of Universe^(2/3). Unfortunately, it’s not simply a plug and chug formula, since the expansion is occurring continuously, you need to apply some calculus. Here’s the formula, but I’ll go through a simple example a little later:
Horizon-Eq
Illustration Credit: Ned Wright
The above integral just takes the ratio of elapsed expansion time to the age of the universe raises it to the 2/3 power and does this over the entire time the expansion is occurring.
What all of this means is that whenever you discuss the size of the universe, you need to apply a scale factor that is relevant TO THE TIME you are interested in. The issue of when is very important because the size of the universe, and the rate at which it was expanding has changed since the universe began.
So, for RIGHT NOW, the size of the universe has expanded to roughly 46.5 billion light years since the Big Bang.
Let’s break down the above integral into some smaller intervals and watch what happens. Let’s use 13 billion years as the age of the universe and let the universe expand for an average of five billion years at three different points in time: 2, 7, and 12 billion years after the Big Bang:
* At age of universe = 2 billion light years: the universe has expanded by a factor of (13/2)^2/3 = 3.48
* At age of universe = 7 billion light years: the universe has expanded by a factor of (13/7)^2/3 = 1.51
* At age of universe = 12 billion light years: the universe has expanded by a factor of (13/12)^2/3 = 1.08
So combining these scale factors over the two intervals above, the universe has expanded to a size of:
(average distance light travels over interval of interest) * (sum of all scale factors).
Plugging in the numbers (we used an elapsed time interval of 5 billion years):
(5 billion light years) * (3.48+1.51+1.08) = 30.37 billion light years.
The 5 billion light year number above is the average distance light traveled in 5 billion years so the units are in light years.
Now, this is a discreet example, taking only three points in time, but already we have a number bigger than 13 billion light years. Since the universe is expanding continuously, we actually need to do the integral above and when you do that, the answer approaches 47 or so billion light years.
Actually, this is a little misleading, the number cited in the above paper does a different analysis and I’m doing something a little different that what the authors of that paper did, so I’m trying to make a number fit that was derived using different techniques in my example above and it won’t work out that way. Still, the end results are similar and nothing is really lost by doing that.
But, ignoring the details for a minute, what I’m really trying to do here is show that the size of the universe isn’t simply the light travel time over the age of the universe. The expansion of the universe requires that you apply a scale factor as outlined above.
If the math is confusing you, just remember this: that scale factor is important. It accounts for the distance the universe has expanded over the time period you’re interested in. It doesn’t go far enough to say that the size of the universe is simply the distance light travels over the course of the age of the universe. Since the creation of time, everything has gotten farther apart, remember Hubble’s Law: everything is speeding away from everything else, all the time.
So, when the Hubble telescope took the deep field images, it provided us with the deepest views we’ve ever seen into the universe. Those galaxies were approaching the farthest edges of our cosmic home, and they weren’t 13.5 billion light years away, they were much, much farther.
For those of you that are not familiar with the basic science of stars and galaxies, the web site http://galaxyzoo.org has a wonderful simplistic way of explaining the basics.
Systems of Stars
Sir Patrick Moore for Galaxy Zoo
What is a Galaxy? The short answer is that it is a system of stars – each of which is a sun. Our Sun, together with the Earth and the planets, belongs to a galaxy made up of around 100 thousand million stars. It is a flattened system, and if we look along its main plane we see many stars in almost the same direction producing the lovely band of light which we call the Milky Way. It is natural to refer to our system as the Milky Way Galaxy; it is slightly above average in size and mass, but it is no means exceptional. Our nearest really important neighbour, M31 in the constellation of Andromeda, is considerably larger than our system. (M31 means that this was the 31st object in a famous catalogue drawn up in the eighteenth century by the French astronomer Charles Messier. The M numbers are still used, but official we turn to the New General Catalogue or NGC; M31 is also NGC 224).
The galaxies are widely spaced. They are found in definite groups or clusters, some sparse and others populous; we belong to the Local Group, which consists of three large systems – our Milky Way, the Andromeda Galaxy M31 and the Triangulum Galaxy M33, plus few of medium size and over two dozen dwarfs. Around 50 million light-years from us we find the Virgo cluster, with over a thousand galaxies of which the largest, M87, far outranks even M31. Because the galaxies are so far away, few are visible without optical aid, and indeed only three can usually be glimpsed; M31, which is on the fringes of naked-eye visibility, and the far south Clouds of Magella, which are satellites of the Milky Way and are ‘only’ around 170,000 light-years from us.
It is widely supposed that all the galaxies are receding from us, so that the entire universe is expanding, but this is not the whole story. The galaxies inside a definite group moving randomly with respect to each other, and indeed M31 is approaching us; in the remote future (certainly over 1,000 million years hence) there will be a collision. The individual stars will seldom hit each other – we may draw a comparison with two orderly crowds moving in opposite directions – but the dust and gas will be colliding all the time, triggering star formation. However, each group of galaxies is racing away from each other group, so that the ‘expanding universe’ concept is correct. During the 1920s the American astronomer Edwin Hubble (after whom the Space Telescope is named) used spectroscopic methods to show that the galaxies really are external systems rather than parts of the Milky Way, and also that the greater the distance of a galaxy, the faster it is moving away from us. This does not mean that we are in a privileged position; the expansion is universal in every sense of the term.
Galaxies are of many kinds. Some are spiral in form like graceful Catherine-wheels; others are elliptical, some more or less spherical, others irregular in outline. There is endless variety; for example we have ‘barred spirals’, where the arms issue from the opposite ends of a bar running along the central plane. Our Milky Way is a barred spiral, although the bar itself is not very obvious, and of course measurements of the exact shape are not easy to make simply because we lie inside the system, around 26,000 light-years from the centre. The centre itself seems to contain a massive Black Hole and this is also true of most large systems. The Milky Way, like other spirals, is rotating; the Sun takes about 225 million years to complete one circuit – a period often called the cosmic year. One cosmic year ago, even the dinosaurs had yet to make their entry. It is interesting to speculate about what conditions will be like one cosmic year hence…
We have found out a great deal about the galaxies, but we cannot claim that our knowledge is at all complete, and there are so many of them that even classification is a problem. This is where Galaxy Zoo is so helpful. It has been organised by professional astronomers, and demonstrates yet again that in astronomy professionals and amateurs can work closely together to their mutual benefit. And – who knows? – while taking part in the programme you may be luck enough to make some unexpected and spectacular discovery. The universe, with its majestic star-cities, is indeed a wonderful place.
The Science
What do we want to know?
Elliptical Galaxy Galaxies, made up of billions of stars like our Sun, are the beacons that light up the structure of even the most distant regions in space. Not all galaxies are alike, however. They come in very different shapes and have very different properties; they may be large or small, old or young, red or blue, regular or confused, luminous or faint, dusty or gas-poor, rotating or static, round or disky, and they live either in splendid isolation or in clusters. In other words, the universe contains a very colourful and diverse zoo of galaxies. For almost a century, astronomers have been discussing how galaxies should be classified and how they relate to each other in an attempt to attack the big question of how galaxies form.
For a more general introduction to galaxies - CLICK HERE
Edwin Hubble early last century divided the galactic zoo into two major categories. There are galaxies shaped like rugby balls (or American footballs) which we call 'ellipticals' and whirlpool-like galaxies which we call 'spirals'. More than 80 years later, there is still major controversy among scientists about how these two principal types are even connected in the global understanding of galaxy formation and evolution. Does one type evolve into the other? In theoretical simulations astronomers have found that the merger of spirals can create an elliptical, and that an elliptical can become a spiral by accretion of further stars and gas during its lifetime. Pictures of real galaxies in the sky taken with the most modern telescopes on earth and space reveal that such processes are indeed happening in nature. But how frequent are mergers? Are they really important? Does every galaxy go through such fundamental transformations during its lifetime?
What do we need to do?
Hubble Telescope Why don't we just look at galaxies and see how they evolve? Galaxies evolve over billions of years, which is why like evolutionary biologists, we can't just sit there and watch galaxies change. Instead, we need to look at the fossil record contained in the galaxies around us which provides only *one* snapshot of the universe.
The way scientists get around this problem is by analysing pictures of galaxies with up-to-date technology in as much detail as possible. Astronomers have spent many decades trying to measure basic galaxy properties such as age, mass or dustiness that may give us some clues as to how they formed and evolved and what precisely the connection between spiral and elliptical galaxies is. However, most studies of galaxies so far have only looked at a few dozen or hundred galaxies in the nearby universe and many aspects of galaxy formation and evolution are still a mystery.
However, with the advent of the 21st century the age of large-scale astronomical surveys has arrived! The Sloan Digital Sky Survey (SDSS) is taking images of a large portion of the sky and will eventually find a million galaxies. With such a large number of galaxies, astronomers can finally begin to understand how they form and evolve by comparing various populations to each other with large enough numbers to draw real conclusions about their origin.
But out of these million galaxies, how do we know which are spirals and which are ellipticals? The answer is simple: look at them! Indeed, until now galaxies have been classified by visual inspection of their images. And in fact, technology is of little help here. It turns out that the human brain is far better than a computer at recognising the patterns that divide ellipticals from spirals. So visual inspection works well for a handful, or even several hundred objects....but one million? There are just too many galaxies for even the most dedicated of astronomers to look at. We need thousands of people to inspect galaxy images and to classify them as spiral or elliptical. We need you to help us.
What can galaxies tell us about the wider Universe?
Spiral Galaxy It is not only those of us studying galaxy formation who are curious about the shapes of galaxies. Cosmologists who study the origin and properties of the Universe itself can also learn from observations of galaxies and, in particular, their rotation. Generally galaxies rotate, and the details of their rotation (angle, speed, direction) depends on the way that they formed and on the properties of the space around them - such as the presence of magnetic fields, or the tidal pull from other structures.
Galaxies form from the gravitational collapse of much larger clouds of gas and, if the cloud has any rotation to start with, it will rotate faster as it gets smaller. This is similar to the way an ice-skater spins faster as they pull their arms in, and it is due to the conservation of angular momentum. In fact, it is this rotation that stops the galaxies collapsing any further as the gravity provides just enough force to keep the gas in its rotational orbit. Thanks to the spiral arms, it is straightforward to observe the rotation direction of spiral galaxies (clockwise or anti-clockwise) just by looking at them. We think that neighbouring galaxies will have formed from the same original large gas cloud. Therefore we expect close galaxies to share some properties, including the angle at which they rotate. By looking at these shared properties over different distances we can tell a lot about the process through which they formed.
But what about the wider Universe? Observing the rotation of galaxies also provides a probe of the large-scale properties of the Universe, and intriguingly there is already some indication from SDSS galaxies that all may not be as it seems! Our current theories about the Universe have it that galaxies should not prefer to rotate one way or the other, and we should therefore observe as many clockwise rotating spiral galaxies as anti-clockwise. This is related to a fundamental assumption we make in cosmology; that there are no special places or special directions in the Universe. Prof. Micheal Longo from the University of Michigan has claimed, in his recent astro-ph preprint, that there is a preferred handedness (rotation direction) of galaxies in the local Universe. This is a revolutionary claim, that could force us to rethink our understanding about the underlying nature of space and employ a much more complicated background model for the Universe. The current claim is based on a sample of just 1660 galaxies from the SDSS survey, but a much larger sample is required to assess the significance of the effect which is where Galaxy Zoo comes in.
For seeing the differences between a spiral, elliptical or merging galaxies the site offers a training tutorial here:
http://galaxyzoo.org/Tutorial.aspx
Anyone any age can participate in this site. The site is well organized and put together. Here's an outline of what it offers:
Home - The Science - How to Take Part - Galaxy Analysis - Forum - Press - Blog - FAQ - Links - Contact Us
I'm leaving you with a few out of hundreds of my favorites from a thousand or more I categorized. I love this site because it constantly makes me ask "wow! What is that!" [I'm addicted to brain stimuli lol!] Because it reminds me of the magnitude and splendors of space. Some of these galaxies are just breath taking and leave me in awe, and because I get insomnia a lot. It's very repetitious like doing a job you really don't have to think about once you are familiar with the with the categories. Many nights has it lulled me to sleep to dream of traveling the stars and exploring the wonders of the universe.
Be blessed dear ones. Think of me, and that thought..will carry me to you.........
http://motherchi.stumbleupon.com/
It gives me an unlimited supply of web site from everywhere on any one of the unlimited amount of things that totally intrigue and fascinates me about life. This is one of the articles that popped up last night that I thought was well worth sharing.
How Can We See Galaxies 47 Billion Light Years Away When the Universe is Only 13 Billion Years Old?
Posted in: cosmology
Hubble ultra deep field This is my second post in the Just Science Week Challenge.
This 2003 paper in Physical Review Letters puts a lower limit on the size of the universe at no smaller than 46.5 billion light years in radius. If the universe is geometrically flat, that is.
In this video I made on the Hubble Deep Field, I mentioned this number and was immediately inundated with questions and comments from people screaming that that number could not possibly be correct. How can the universe be that big if the fastest anything can travel is the speed of light? The universe simply CAN’T be larger than the distance light travels during age of the universe, right?
Wrong.
It is true that the universe is 13.5 billion years old, and it is also true that nothing can travel faster than the speed of light. But it does NOT follow that the size of the universe is simply the distance light traveled in 13.5 billion years. You can’t stop there. Why?
Because the universe is expanding, and has been for 13.5 billion years.
Remember yesterday’s post? Everything in the entire universe is flying away from each other at a rate linearly proportional to its distance. That’s Hubble’s Law. The distance that light has to travel over time is continuously getting bigger and you MUST take that into account.
Technorati Tags: cosmology
Remember in my last post, we’ve established that the universe is expanding at roughly the Hubble Constant, and that number is a function of time. It matters WHEN you take your measurement of the redshifts of far away galaxies. Right now, the universe is expanding at about 71 km/sec/Mpc and is accelerating.
Here's an interesting article I found web surfing today on one of my favorite subjects.I help categorize galaxies at galazyzoo.org.
A somewhat simpler way to think of the expansion rate of the universe is that it expands at roughly the age of the universe to the 2/3 power: Age Of Universe^(2/3). Unfortunately, it’s not simply a plug and chug formula, since the expansion is occurring continuously, you need to apply some calculus. Here’s the formula, but I’ll go through a simple example a little later:
Horizon-Eq
Illustration Credit: Ned Wright
The above integral just takes the ratio of elapsed expansion time to the age of the universe raises it to the 2/3 power and does this over the entire time the expansion is occurring.
What all of this means is that whenever you discuss the size of the universe, you need to apply a scale factor that is relevant TO THE TIME you are interested in. The issue of when is very important because the size of the universe, and the rate at which it was expanding has changed since the universe began.
So, for RIGHT NOW, the size of the universe has expanded to roughly 46.5 billion light years since the Big Bang.
Let’s break down the above integral into some smaller intervals and watch what happens. Let’s use 13 billion years as the age of the universe and let the universe expand for an average of five billion years at three different points in time: 2, 7, and 12 billion years after the Big Bang:
* At age of universe = 2 billion light years: the universe has expanded by a factor of (13/2)^2/3 = 3.48
* At age of universe = 7 billion light years: the universe has expanded by a factor of (13/7)^2/3 = 1.51
* At age of universe = 12 billion light years: the universe has expanded by a factor of (13/12)^2/3 = 1.08
So combining these scale factors over the two intervals above, the universe has expanded to a size of:
(average distance light travels over interval of interest) * (sum of all scale factors).
Plugging in the numbers (we used an elapsed time interval of 5 billion years):
(5 billion light years) * (3.48+1.51+1.08) = 30.37 billion light years.
The 5 billion light year number above is the average distance light traveled in 5 billion years so the units are in light years.
Now, this is a discreet example, taking only three points in time, but already we have a number bigger than 13 billion light years. Since the universe is expanding continuously, we actually need to do the integral above and when you do that, the answer approaches 47 or so billion light years.
Actually, this is a little misleading, the number cited in the above paper does a different analysis and I’m doing something a little different that what the authors of that paper did, so I’m trying to make a number fit that was derived using different techniques in my example above and it won’t work out that way. Still, the end results are similar and nothing is really lost by doing that.
But, ignoring the details for a minute, what I’m really trying to do here is show that the size of the universe isn’t simply the light travel time over the age of the universe. The expansion of the universe requires that you apply a scale factor as outlined above.
If the math is confusing you, just remember this: that scale factor is important. It accounts for the distance the universe has expanded over the time period you’re interested in. It doesn’t go far enough to say that the size of the universe is simply the distance light travels over the course of the age of the universe. Since the creation of time, everything has gotten farther apart, remember Hubble’s Law: everything is speeding away from everything else, all the time.
So, when the Hubble telescope took the deep field images, it provided us with the deepest views we’ve ever seen into the universe. Those galaxies were approaching the farthest edges of our cosmic home, and they weren’t 13.5 billion light years away, they were much, much farther.
For those of you that are not familiar with the basic science of stars and galaxies, the web site http://galaxyzoo.org has a wonderful simplistic way of explaining the basics.
Systems of Stars
Sir Patrick Moore for Galaxy Zoo
What is a Galaxy? The short answer is that it is a system of stars – each of which is a sun. Our Sun, together with the Earth and the planets, belongs to a galaxy made up of around 100 thousand million stars. It is a flattened system, and if we look along its main plane we see many stars in almost the same direction producing the lovely band of light which we call the Milky Way. It is natural to refer to our system as the Milky Way Galaxy; it is slightly above average in size and mass, but it is no means exceptional. Our nearest really important neighbour, M31 in the constellation of Andromeda, is considerably larger than our system. (M31 means that this was the 31st object in a famous catalogue drawn up in the eighteenth century by the French astronomer Charles Messier. The M numbers are still used, but official we turn to the New General Catalogue or NGC; M31 is also NGC 224).
The galaxies are widely spaced. They are found in definite groups or clusters, some sparse and others populous; we belong to the Local Group, which consists of three large systems – our Milky Way, the Andromeda Galaxy M31 and the Triangulum Galaxy M33, plus few of medium size and over two dozen dwarfs. Around 50 million light-years from us we find the Virgo cluster, with over a thousand galaxies of which the largest, M87, far outranks even M31. Because the galaxies are so far away, few are visible without optical aid, and indeed only three can usually be glimpsed; M31, which is on the fringes of naked-eye visibility, and the far south Clouds of Magella, which are satellites of the Milky Way and are ‘only’ around 170,000 light-years from us.
It is widely supposed that all the galaxies are receding from us, so that the entire universe is expanding, but this is not the whole story. The galaxies inside a definite group moving randomly with respect to each other, and indeed M31 is approaching us; in the remote future (certainly over 1,000 million years hence) there will be a collision. The individual stars will seldom hit each other – we may draw a comparison with two orderly crowds moving in opposite directions – but the dust and gas will be colliding all the time, triggering star formation. However, each group of galaxies is racing away from each other group, so that the ‘expanding universe’ concept is correct. During the 1920s the American astronomer Edwin Hubble (after whom the Space Telescope is named) used spectroscopic methods to show that the galaxies really are external systems rather than parts of the Milky Way, and also that the greater the distance of a galaxy, the faster it is moving away from us. This does not mean that we are in a privileged position; the expansion is universal in every sense of the term.
Galaxies are of many kinds. Some are spiral in form like graceful Catherine-wheels; others are elliptical, some more or less spherical, others irregular in outline. There is endless variety; for example we have ‘barred spirals’, where the arms issue from the opposite ends of a bar running along the central plane. Our Milky Way is a barred spiral, although the bar itself is not very obvious, and of course measurements of the exact shape are not easy to make simply because we lie inside the system, around 26,000 light-years from the centre. The centre itself seems to contain a massive Black Hole and this is also true of most large systems. The Milky Way, like other spirals, is rotating; the Sun takes about 225 million years to complete one circuit – a period often called the cosmic year. One cosmic year ago, even the dinosaurs had yet to make their entry. It is interesting to speculate about what conditions will be like one cosmic year hence…
We have found out a great deal about the galaxies, but we cannot claim that our knowledge is at all complete, and there are so many of them that even classification is a problem. This is where Galaxy Zoo is so helpful. It has been organised by professional astronomers, and demonstrates yet again that in astronomy professionals and amateurs can work closely together to their mutual benefit. And – who knows? – while taking part in the programme you may be luck enough to make some unexpected and spectacular discovery. The universe, with its majestic star-cities, is indeed a wonderful place.
The Science
What do we want to know?
Elliptical Galaxy Galaxies, made up of billions of stars like our Sun, are the beacons that light up the structure of even the most distant regions in space. Not all galaxies are alike, however. They come in very different shapes and have very different properties; they may be large or small, old or young, red or blue, regular or confused, luminous or faint, dusty or gas-poor, rotating or static, round or disky, and they live either in splendid isolation or in clusters. In other words, the universe contains a very colourful and diverse zoo of galaxies. For almost a century, astronomers have been discussing how galaxies should be classified and how they relate to each other in an attempt to attack the big question of how galaxies form.
For a more general introduction to galaxies - CLICK HERE
Edwin Hubble early last century divided the galactic zoo into two major categories. There are galaxies shaped like rugby balls (or American footballs) which we call 'ellipticals' and whirlpool-like galaxies which we call 'spirals'. More than 80 years later, there is still major controversy among scientists about how these two principal types are even connected in the global understanding of galaxy formation and evolution. Does one type evolve into the other? In theoretical simulations astronomers have found that the merger of spirals can create an elliptical, and that an elliptical can become a spiral by accretion of further stars and gas during its lifetime. Pictures of real galaxies in the sky taken with the most modern telescopes on earth and space reveal that such processes are indeed happening in nature. But how frequent are mergers? Are they really important? Does every galaxy go through such fundamental transformations during its lifetime?
What do we need to do?
Hubble Telescope Why don't we just look at galaxies and see how they evolve? Galaxies evolve over billions of years, which is why like evolutionary biologists, we can't just sit there and watch galaxies change. Instead, we need to look at the fossil record contained in the galaxies around us which provides only *one* snapshot of the universe.
The way scientists get around this problem is by analysing pictures of galaxies with up-to-date technology in as much detail as possible. Astronomers have spent many decades trying to measure basic galaxy properties such as age, mass or dustiness that may give us some clues as to how they formed and evolved and what precisely the connection between spiral and elliptical galaxies is. However, most studies of galaxies so far have only looked at a few dozen or hundred galaxies in the nearby universe and many aspects of galaxy formation and evolution are still a mystery.
However, with the advent of the 21st century the age of large-scale astronomical surveys has arrived! The Sloan Digital Sky Survey (SDSS) is taking images of a large portion of the sky and will eventually find a million galaxies. With such a large number of galaxies, astronomers can finally begin to understand how they form and evolve by comparing various populations to each other with large enough numbers to draw real conclusions about their origin.
But out of these million galaxies, how do we know which are spirals and which are ellipticals? The answer is simple: look at them! Indeed, until now galaxies have been classified by visual inspection of their images. And in fact, technology is of little help here. It turns out that the human brain is far better than a computer at recognising the patterns that divide ellipticals from spirals. So visual inspection works well for a handful, or even several hundred objects....but one million? There are just too many galaxies for even the most dedicated of astronomers to look at. We need thousands of people to inspect galaxy images and to classify them as spiral or elliptical. We need you to help us.
What can galaxies tell us about the wider Universe?
Spiral Galaxy It is not only those of us studying galaxy formation who are curious about the shapes of galaxies. Cosmologists who study the origin and properties of the Universe itself can also learn from observations of galaxies and, in particular, their rotation. Generally galaxies rotate, and the details of their rotation (angle, speed, direction) depends on the way that they formed and on the properties of the space around them - such as the presence of magnetic fields, or the tidal pull from other structures.
Galaxies form from the gravitational collapse of much larger clouds of gas and, if the cloud has any rotation to start with, it will rotate faster as it gets smaller. This is similar to the way an ice-skater spins faster as they pull their arms in, and it is due to the conservation of angular momentum. In fact, it is this rotation that stops the galaxies collapsing any further as the gravity provides just enough force to keep the gas in its rotational orbit. Thanks to the spiral arms, it is straightforward to observe the rotation direction of spiral galaxies (clockwise or anti-clockwise) just by looking at them. We think that neighbouring galaxies will have formed from the same original large gas cloud. Therefore we expect close galaxies to share some properties, including the angle at which they rotate. By looking at these shared properties over different distances we can tell a lot about the process through which they formed.
But what about the wider Universe? Observing the rotation of galaxies also provides a probe of the large-scale properties of the Universe, and intriguingly there is already some indication from SDSS galaxies that all may not be as it seems! Our current theories about the Universe have it that galaxies should not prefer to rotate one way or the other, and we should therefore observe as many clockwise rotating spiral galaxies as anti-clockwise. This is related to a fundamental assumption we make in cosmology; that there are no special places or special directions in the Universe. Prof. Micheal Longo from the University of Michigan has claimed, in his recent astro-ph preprint, that there is a preferred handedness (rotation direction) of galaxies in the local Universe. This is a revolutionary claim, that could force us to rethink our understanding about the underlying nature of space and employ a much more complicated background model for the Universe. The current claim is based on a sample of just 1660 galaxies from the SDSS survey, but a much larger sample is required to assess the significance of the effect which is where Galaxy Zoo comes in.
For seeing the differences between a spiral, elliptical or merging galaxies the site offers a training tutorial here:
http://galaxyzoo.org/Tutorial.aspx
Anyone any age can participate in this site. The site is well organized and put together. Here's an outline of what it offers:
Home - The Science - How to Take Part - Galaxy Analysis - Forum - Press - Blog - FAQ - Links - Contact Us
I'm leaving you with a few out of hundreds of my favorites from a thousand or more I categorized. I love this site because it constantly makes me ask "wow! What is that!" [I'm addicted to brain stimuli lol!] Because it reminds me of the magnitude and splendors of space. Some of these galaxies are just breath taking and leave me in awe, and because I get insomnia a lot. It's very repetitious like doing a job you really don't have to think about once you are familiar with the with the categories. Many nights has it lulled me to sleep to dream of traveling the stars and exploring the wonders of the universe.
Be blessed dear ones. Think of me, and that thought..will carry me to you.........
Tags: galaxies, galaxyzoo, motherchi, space, stumbleupon, universe
- Attachments:
-
-
587742013833609414.jpeg, 26 KB -
588017627219361830.jpeg, 13 KB
-
588010878235115736.jpeg, 13 KB
-
Replies to This Discussion
-
Permalink Reply by PHILOXENIA Admin on -
Hello MotherChi!
This is fascinating! Astrophysics was always my beloved subject. To get my high school diploma I had to make a special work. I did that in astrophysics. At that time, in the middle of the 70-ties the scientists believed that our solar system was 5.0 billion years old and the Universe 7.0 billion years. The CERN project is giving us their theory on 13.8 billion years back as the start point of universe and on that they started the Big Bang project last Wednesday (Sept. 10th, 2008).
The Big Bang is one of the theories on how everything started. Using only 4-5% of our brain we will change our theories many - many times. We do only understand 4% of the universe. It goes parallel with our brain ???
Nobody can for sure tell us how old the universe is. There is aslo a problem. Panentheism (PanEnTheism) claims the Creator was before the Idea (Creation). Man will always be a playing child trying to find the roots to everything!
There is much to write but lets give our friends to say their meaning and opinion first.
Happy Week End
Georgios
-
Permalink Reply by Marius Wlassak on -
Hello Motherchi,
I enjoyed all You wrote and it is outstanding and very interesting.
I also agree that we do not know anything yet and if we could only understand on a smaller scale and truly could bring up an infinite love for the smaller things, maybe after we will be free we can someday look from outside travelling this expansion and laugh from our hearts what we will hopefully then experience or see.
Happy weekend from around the corner ;-),
Marius
-
Permalink Reply by Motherchi on -
Thank-you for your response Marius, you are most kind. I greet you in love with an open mind and heart. Indeed do I agree with you! My quantum mind sees both ways. I was gifted as a child to see things from a CSI perspective. My first experience was a grape vine that I thoughtlessly broke. I interpreted the fluid that leaked from the break as blood. I could see how the stem had a bunch of straws that branched out throughout the leave. When I'd look at a humming bird I would see heat rainbows of red and blue and white and a tiny heart fluttering faster than I could count almost in unison of his fast fluttering wings. I was 4 at the time or so and this perception greatly influenced how I view all life around me. I don't just stop and smell the roses, I ponder savor the life and beauty of it. The sight of life is a gift for anyone who desires to see. I have discovered in everything is infinity. The more you look, the more you will find......be blessed
About
Birthdays
Birthdays Today
Badge
BELOVED PHILOXENIA ACTIVITIES IN NING
© 2009 Created by PHILOXENIA Admin on Ning. Create a Ning Network!
