The Faint Red Dot --Is This the Most Distant Known Object in the Observable Universe?

A deep optical image of the afterglow of the gamma-ray burst GRB 090429B, arguably the most distant object known in the universe.The light from this object has been traveling towards us for about 13.2 billion years, or 96% of the age of the universe. Since the universe is not static but expanding, today this object is much farther away than 13.2 billion light-years - more like about thirty billion light-years.

The most distant objects in the universe are also the oldest -- or at least that is how they appear to us, because their light has had to travel for billions of years to get here. They are also extraordinarily faint since they are so far away, and only in the last decade have astronomers been able to stretch their vision using the newest telescopes and clever techniques.

One such innovation occurred with the launch of the NASA Swift satellite in 2004; it searches for bursts of gamma-ray emission, called GRBs. These flashes, thought to result from the especially spectacular deaths of massive stars, are the brightest events in the cosmos during their brief (only seconds-long) existence. But because they are so bright, they can be seen even when they are billions of years away.

A large international team of astronomers including CfA astronomers Edo Berger, Alicia Soderberg, and Ryan Foley used the Swift satellite to spot a GRB that rapid, ground-based followup studies determined was possibly the most distant object known (but measurement uncertainties allow a few other candidates to compete for this title).

The scientists were unable to detect any faint trace of the putative galaxy in which this massive star once lived, helping to confirm the great distance of this GRB. Other important details in their new paper confirm that the object is similar to more nearby GRBs, and consequently that - even at this early stage of cosmic life - at least some stars already resembled stars in our local universe.

Provided by Harvard-Smithsonian Center for Astrophysics

Comments

[Bob Greenwade]

If it's 30 billion light-years distant, then either the universe is at least 30 billion years old, or the recently-mentioned theory that light traveled much faster in the early universe has to be correct.

Or perhaps it's something else, eh? Could something be wrong with the way we measure these things? Is anyone even seriously considering that possibility, and not being widely ridiculed over it?

[Frank]

regarding bob's comment:
The article says "The light from this object has been traveling (...) 13.2 billion years, or 96% of the age of the universe."
Remember that we are always looking back in time.
The 30 billion light-years distance is estimated for today's universe, which has been expanding for 13.2 billion years after the light we see today has left this object. This does not imply that the spped of light is not constant. But it tells us that 13 billion years ago, this GRB was more than 17 billion lightyears closer tahn today. The expansion of the universe is like blowing up a ballon with stars painted onto its surface; an expansion of spacetime itself.
The expansion of spacetime is changing the distance to this object. This effect is not limited by the speed of light.

[Amakiir]

Bob Greenwade, the universe is expanding. Say you draw a line from point A to point B in the universe, with a distance of 10 light years at t=0 (I am going to use simplified numbers and math just to make the point, you can look up exact figures if you want). You begin traveling along this line moving at the speed of light. In five years you travel five light years. The distance between A and B at t=0 was 10 light years, and you have traveled 5 light years, so you should now be 5 light years away from point B, right? Well, it turns out you aren't. You are now 6 light years away from the destination. How is that? So you travel 3 more years, moving at the speed of light. After three years you have traveled 3 light years. Point B was 6 light years away at t=5, and you have traveled 3 additional light years, so you should be 3 light years away, right? Well, it turns our point B is now 3.3 light years away.

At t=0, it was 10 light years. You traveled 5 light years, and at t=5, you were still 6 light years away. So you traveled an additional 3 light years, and at t=8 you were 3.6 light years away.

You travel an additional 1.8 light years. You should be 1.8 light years away, right? But this time you are 2.2 light years away. So you travel another 1.1 light years and you are 1.2 light years away. So you travel .6 light years, and you are .8 light years away. Et cetera, et cetera until you reach your destination.

You started exactly 10 light years away from your destination, but you ended up traveling 13.1 light years. How is this so?

Well, the universe is expanding. For every light year separating to points in space, a few km of space expands between. I believe it is something like 70km/mpc/second. A megaparsec being like 3 million light years or so. So 70km per 3 million light years per second. That doesn't seem like much, but it adds up. It means that distant objects can expand billions of light years before light can catch up. It means that if objects are far enough away from each other, light can never exceed the rate of expansion. Two objects sufficiently far enough away will never, ever produce light that can be seen by one another. That is why there is an 'observable' universe. Anything further out than the observable universe is too far away to ever be seen by earth. It is unobservable. This is why the observable universe expands out in a sphere, essentially with the center of the sphere being the sun. We orbit about the sun, so the sun is the center of our observable universe. Light that beings a certain distance away will never, ever reach us.

So we are essentially saying that our best estimate of the universe is 13.75 billion years or whatever (and we find this in many different ways). So light that is on the edge of the visible universe must have traveled that long, because it is light that has traveled the furthest to reach us. So if light traveled 13.75 billion years to reach us, with the current rate of expansion in the universe, then it must be 30, 40 billion light years away from us right now. Now being very subjective. How far away was in produced this light? Well, we know it was far closer than 13.75 billion years, otherwise the light wouldn't have reached us yet. With the current rate of expansion we can predict how far away this light was.

[me]

So when a "light" is created, does it not have a starting point? If we see the moon's light, we see one side of it. When we view Mars, its the same thing. I'm confused as to why the origination of the light is effected by expanding space. Does the origin of the light actually change? Or is that a very theoretical thought?

[Amakiir]

Light is made of photons. You can think about it using the Bohr model of the atom. You have a Proton in the center, with an electron going around it in an orbit, similar to how Earth goes around the sun. There are multiple orbits the electron can take, each with a different energy level. When the electron gains energy, it goes from an inner orbit to an outer orbit. When it loses energy it goes from an outer orbit to an inner orbit. When it drops in energy from one orbit to another, it releases a photon. This photon is exactly the energy difference between the more energetic and less energetic orbits. If you take that photon and shoot it into the electron, it will move up exactly back into its orbit.

Anyhow, when the electron drops its orbit, it releases a photon. This photon moves in some random direction, in a straight line. Well, it moves in a wave, but the wave moves in a straight line. It moves at the speed of light. Light cannot speed up or slow down, it always moves at the same speed. This is very important. No matter what your perspective is, light will always go the same speed.

So you have point A and point B which are distance X light years (ly) apart. Point A has a single electron drop in energy, firing off a single photon directly in a straight line towards B. Since A is Xly from B, and the speed of light (c) is always the same, then you would expect the photon to reach B in X years.

But there is a problem. Space expands. This is a difficult concept to grasp. The distance between objects gets longer. The objects aren't moving, but the space between them is slowly getting larger.

Think about a balloon. Mark two points on the balloon and label them A and B using a marker. Now blow up the balloon slowly. The two points get further and further away from each other. This is kind of like how space is expanding, except space is expanding in every dimension.

The things in space are not necessarily moving. Space is getting longer.

If you have 3 points in space making a triangle. You measure the sides of each of the triangle and find the sides are 3x, 4x, and 5x. As space expands, this ratio will always remain the same. The points are not moving relative to each other, but the space between them is getting larger. At t=0, x=1. At t=1, x=2. At t=2, x=3. Each time the space between each point is getting larger and larger, but none of them are moving in any direction. Space is getting longer.

--

The light we are talking about is being created by stars, galaxies, or whatever else. Some basic source of light. Lets just say it is a star to make things easier. The star is emitting some tremendous amount of energy, which heats up some super hot hydrogen atom, and bumps an electron up an energy level. This energy is very unstable, and eventually the electron falls back down, and creates a photon. This photon begins moving towards earth at the speed of light.

Now assume some long period of time passes, say a billion years. The light has moved a billion light years directly towards earth. Its star has not moved. Earth has not moved. But the distance between the photon and its original star is not a billion light years. It is, 1.2 billion light years or whatever. Further more, whatever distance Earth was away, say it was 10 billion light years away, is now 9.9 billion light years away or whatever it is.

--

So the point here is that the object that made the light isn't moving, at least it isn't moving due to the expansion of space. Earth isn't moving, at least not due to the expansion of space. But the distance between Earth and the star that makes the light is expanding. So the distance between Earth and the star when the light is created is significantly smaller than the distance between Earth and the star at present time.

Light takes time to travel. The light you see is from the past, and it is from a point in time when the universe was smaller and whatever object that created the light was closer to Earth.

The length of time the object travels does not represent how far away the object was when the light was created, and it doesn't represent how far the object is from us today.

[Amakiir]

I should also say that other forces in physics completely dominate the expansion of space. Objects bound by gravity do not expand relative to each other, but they do expand relative to other objects that are too far away to have gravity effect them. For instance, Earth and the sun are not expanding away from one another. The sun isn't even expanding away from other stars in the Milky Way galaxy. The dwarf galaxies in our local group aren't even expanding away from one another. The Andromeda galaxy is going to eventually crash into the Milky Way. But galaxies outside of our little local group are expanding away from us.

[ntlgnce]

Lets get this straight, The light from the farthest object is 13.6 billion light years old, and 96% of the age of the universe. So to say that would say that that star got where it was in just 4% of the age of the universe. or around 2 billion light years.. Which would also say that everything that we know got to where it is right not in about 15 billion light years.. So if scientists found more of these 13.6 billion light years away objects, in theory they should be very very very close together. Or less then 5 billion light years away from each other. Do you get it now guys? I have been trying to explain that for years to everyone who currently thinks they can see back to close to the big bang or see the reminants of it. Or whatever they expect to see.. NO they will never be able to, as,

A, the big bang is wrong, or the age of the universe is greatly underestimated, by more then two or three times whats currently the accepted age..
or B, light across vast distances is more like a quantom particle or twisted pair, ( where what happens to one happens to the other.. )... NOT completely but generally speaking..

[ntlgnce]

Lets get this straight, The light from the farthest object is 13.6 billion light years old, and 96% of the age of the universe. So to say that would say that that star got where it was in just 4% of the age of the universe. or around 2 billion light years.. Which would also say that everything that we know got to where it is right not in about 15 billion light years.. So if scientists found more of these 13.6 billion light years away objects, in theory they should be very very very close together. Or less then 5 billion light years away from each other. Do you get it now guys? I have been trying to explain that for years to everyone who currently thinks they can see back to close to the big bang or see the reminants of it. Or whatever they expect to see.. NO they will never be able to, as,

A, the big bang is wrong, or the age of the universe is greatly underestimated, by more then two or three times whats currently the accepted age..
or B, light across vast distances is more like a quantom particle or twisted pair, ( where what happens to one happens to the other.. )... NOT completely but generally speaking..

[ntlgnce]

Lets get this straight, The light from the farthest object is 13.6 billion light years old, and 96% of the age of the universe. So to say that would say that that star got where it was in just 4% of the age of the universe. or around 2 billion light years.. Which would also say that everything that we know got to where it is right not in about 15 billion light years.. So if scientists found more of these 13.6 billion light years away objects, in theory they should be very very very close together. Or less then 5 billion light years away from each other. Do you get it now guys? I have been trying to explain that for years to everyone who currently thinks they can see back to close to the big bang or see the reminants of it. Or whatever they expect to see.. NO they will never be able to, as,

A, the big bang is wrong, or the age of the universe is greatly underestimated, by more then two or three times whats currently the accepted age..
or B, light across vast distances is more like a quantom particle or twisted pair, ( where what happens to one happens to the other.. )... NOT completely but generally speaking..

[ntlgnce]

Lets get this straight, The light from the farthest object is 13.6 billion light years old, and 96% of the age of the universe. So to say that would say that that star got where it was in just 4% of the age of the universe. or around 2 billion light years.. Which would also say that everything that we know got to where it is right not in about 15 billion light years.. So if scientists found more of these 13.6 billion light years away objects, in theory they should be very very very close together. Or less then 5 billion light years away from each other. Do you get it now guys? I have been trying to explain that for years to everyone who currently thinks they can see back to close to the big bang or see the reminants of it. Or whatever they expect to see.. NO they will never be able to, as,

A, the big bang is wrong, or the age of the universe is greatly underestimated, by more then two or three times whats currently the accepted age..
or B, light across vast distances is more like a quantom particle or twisted pair, ( where what happens to one happens to the other.. )... NOT completely but generally speaking..

[Amakiir]

First, light year isn't a measure of time, it is a measure of distance.

Second, the light we can see may not even be a significant fraction of the total universe. It could be a tiny, tiny, tiny portion of a nearly infinite universe. Or the universe could simply be infinite. Or the observable universe could actually be the entire universe. Or, and this is kind of strange, the observable universe could be LARGER than the actual universe.

Third "close together' is very relative.

[JFoley]

I may be misunderstanding you but if you're asking why things aren't more compact as you get close to the big bang, it's because everything didn't explode out of a single point. This was a misconception that had puzzled me for a while.
The big bang shouldn't be visualized as everything we know exploding from a single point. But rather like the balloon example above, all of space-time expanded as a whole in less than a second. Like a very small miniature model of space blew up almost instantly to actual size. This is inflation. So the relative distances between matter are no more compact just following the big bang than they are now.
So what all this means is, it doesn't matter what direction you look in space. The big bang occurred everywhere. The deeper you look out in any direction, the longer the time those photons had to travel, therefore, the closer you get back to the big bang.

[Amakiir]

Also, the Big Bang didn't blow up in 3D, it blew up in 4D. It is a 4D object that is expanding, and the surface of the 4D object is our 3D world, which is expanding with the 4D. If you imagine a balloon, the rubber itself kind of approximates a 2D surface, and as you blow up the balloon it grows in 3D and becomes this large sphere type thing. The '2D' surface of the balloon stretches to cover this ever increasing sphere type 3D object.

[thunderza]

From a newby to astronomy and all
Thanks Amakir for your posts, I understand a bit more than I use to, but I suppose its always better to be a bit of a skeptic.

[DaisyDog]

Thank you for your clear, patient, explanations Amakiir. I find these type of posts to be both enjoyable and educational reading.

[Matt Rhodes]

To me, and possibly to many others, Space and the Universe have usually represented the same thing. This is also the most common interpretation put forward in education, in many books and on TV. Where Space is, and possibly ends according to some theories, there the Universe is and ends too. Or so I used to think until I came up with this odd idea a while ago.

Suppose Space - totally empty and devoid Space - is not quite something that exists, but merely a state characterized by the absence of everything, including matter. Then, could it not as well be that empty space is omnipresent and thus “infinite?” Empty Space was the natural initial state for everything; as a nothing, naught, non-existence?

Space, as a state of non-existence, would solve the age-old question about what "exists" beyond the Universe, beyond the furthest grouping of galaxies; namely nothing. And it was in this Nothing that “Something” was born through the Big-Bang 14 billion years ago; a something we have later chosen to call our Universe. And in this Space our Universe, or possibly many other Universes, could be sailing along like islands in a black void.

[Frank]

It it even possible that space is unlimited, without requiring the "nothing".

* from a mathematics point of view, an infinite space can expand by any factor (see "Hilbert's paradox of the Grand Hotel", http://en.wikipedia.org/wiki/Hilbert_hotel_paradox). Basicially, space could expand by a factor of - lets say - two, and still fit into the same "universe".

* The "multiverse" theories explain several levels of "infinity" in the universe (see Tegmark's classification, http://en.wikipedia.org/wiki/Multiverse)

* some string theories suggests that a "universe" is only an area in space that has a certain "ground state". Different such areas exists. At their borders, the groud states may "flip", causing a certain area to grow (faster than light). For an observer from inside, this looks like an inpflating universe. (see http://en.wikipedia.org/wiki/Bubble_theory or http://en.wikipedia.org/wiki/Introduction_to_M-theory or http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-9205.pdf)

* if your brains did not volatilize until now, you really understand why the hitchhiker's guide simply states "you are here" ;-))

But this is more philosophy than physics, as we will not be able to see the complete picture for a very long time...

[man]

So what we see now originated 13.5 billion years ago!! that object may not be in existence right now. Is it not ridiculous? may be fascinating to read such fiction but is it really worthwhile to
study such non existing ones when so many problems plaguing Earth
still intimidate us?

[igotyafiguredout]

something to chew on , measured by what we see? what about what we dont see? better yet what about what was there and has long since passed and we dont see anymore due to non existence? I was always taught you cant get something from nothing. Now tell me where did the singularity come from. Which came first the chicken or the egg theory....enjoy life and be thankful cause it may never happen again.