13.7 billion years.

NASA

The Andromeda Galaxy, seen at ultraviolet wavelengths. This mosaic covers a region 200,000 light-years wide and is made up of 330 individual images taken by NASA's Swift satellite.

The State Of The Universe Address

by Marcelo Gleiser

I would like to start by thanking those members of the human race who, through their inventiveness and diligence, have learned so much about my properties over the past few millennia. In this address I will, for the sake of clarity, adopt the human notion of time, which is indeed very practical, although somewhat quaint. Those other intelligences spread around my domain should pay attention to what these humans are doing.
I continue to expand, as I have for the past 13.7 billion years. Things were quite lonely, I must say, for most of this time. Deep silence, no minds tinkering with the mysteries that I ingeniously create to entertain myself over the eons. Yes, for within the initial furnace that followed the big bang, my birth so to speak, particles of matter and radiation simply zoomed around with no chance of forming anything very stable. I was filled in those days with a hot soup of primordial matter and radiation — nothing more.

Only after some four-hundred-thousand years the first atoms appeared. And even so, only the simplest of them were present, what humans call hydrogen and helium. It’s true that I am partial to humans. There are many brute forms of life across my volume, some quite curious to behold. However, in humans I find that spark of magic that makes all the difference, an appreciation for things that transcend them. While most life forms simply live, humans aspire to more than that. They have concepts such as dignity, respect and love that I find quite creative. Perhaps that’s the reason why while all other intelligent life forms self-destruct after they reach a certain level of technological prowess, humans have managed to remain alive, even if currently struggling.
Those first atoms of hydrogen, through the workings of gravity, managed to coalesce into highly dense spherical blobs called stars. In their cores, when temperatures reach some 15 million degrees, hydrogen fuses into helium, the second most complex chemical element. This is the transmutation that holds the key to all complexity within my volume. Yes, nothing is more important than this fusion. From it, stars ignite and produce the light and energy that will warm up their court of planets and moons; from it, life extracts its energy; from it, when these stars approach the end of their lives, heavier atoms are formed, sprinkling the interstellar space with the ingredients that make life possible throughout. This is my dance of creation and destruction, the true harmony of the worlds: dying stars giving birth to new ones and to the ingredients that make life possible.
These clever humans have figured all this out in only a few hundred years. They have even realized that my expansion is variable, sometimes faster sometimes slower, depending on what kinds of matter and radiation are more important. They know that for the past few billion years I’ve been going through a period of accelerated expansion, that the distances between galaxies is increasing quite fast. I loved to see the look of total surprise in the faces of some of the human scientists when they found this out. Hopefully, they are finally learning that we things cosmic it’s best to keep their minds open, and to have the humility to accept that no view of mine that they acquire will ever be complete. The more they probe into my mysteries the more surprises they will find. That amuses me greatly and surely keeps them busy. I hope those other brutes across my domain, who spend so much of their times fighting and killing each other for pathetic reasons, will learn that lesson, and learn to engage themselves in the pursuit of knowledge.
I know I was quite partial when I allowed Earth to form 4.6 billion years ago. Yes, it’s an unusual world, very special. For among the trillions of worlds out there, very few bear the properties of this small blue jewel of mine. I am intrigued by how slow humans have been in realizing the importance of their world. Especially now that they have the means to study other worlds in some detail, they should be praising their gods (well, me really) for their luck. Had things been only slightly different, they’d have a lot of trouble surviving there. Do they realize this? I’m not sure, at least judging from the disappearing of green over the Earth’s surface. Whatever they are doing there, it’s on a global scale. Interesting for me to see that a single species can evolve to affect the whole planet willingly and when it does so, it seems to act destructively. I guess it’s hard for them to strike a balance between their need to survive and their planet’s need to replenish its resources. Hopefully they will learn faster than the others. I’m tired of looking at desert worlds across my domain, worlds that once were as alive as Earth is now.


Let’s start with our universe.
What an amazing place to be alive! Some 200 billion galaxies, each with some 200 billion stars, a good fraction of them with planets, and these planets with moons. Trillions of worlds besides our own, each unique, each with its own history, with its own mysteries and wonders.
If Copernicus thought (he didn’t, but many who followed him did) that displacing the Earth from the center of the cosmos would make the cosmos and the Earth less interesting, he was quite wrong. This expanding fabric of space, with texture so rich we couldn’t have imagined even 20 years ago, will never cease to amaze us.
What’s beyond space? What happened before the big bang, the event that kick-started time? These are the questions so many want to understand. Can we? Yes, we can!
  Our present measurements — and remember, all we can say about the world is what we can measure of it; the rest may be cool to talk about in parties but it’s speculation until measured — indicate that space is flat: this means that it goes on forever.
Now, do we know that for sure? Not really. All we can say is that the portion of space that we can measure, that is, the portion that is delimited by the distance light traveled since the initial bang 13.7 billion years ago, is flat or very very nearly so. Think of a beach and the horizon in the distance. You know the ocean doesn’t end there, just what you can see of it. Well, it's the same with space. We can see as far as light traveled since the beginning of time, a staggering 45 billion lightyears, in round numbers. Beyond that there is more space, and probably more galaxies, more stars, more planets. (Why 45 billion lightyears and not 13.7? Because light gets a “push” from the cosmic expansion as a surfer riding on a wave and covers a larger distance than only 13.7 billion light-years.)
How can we be so certain?
Because our measurements tell us that the laws of physics and chemistry are the same across the vastness of space. How mind-boggling is that? We can tell what a star is made of without ever needing to go there; we can tell how galaxies formed some 10 billion years ago, way before Earth even existed. As we look into space we look into the past: the farther away, the farther into the beginning. Who said there is no magic in science?
And what about “the” beginning? Well, we don’t really know. But we do know a lot of the cosmic history all the way down to one trillionth of a second after the big bang. Not too bad for a science that is only about 400 years old, right? We also know that there isn’t much sense in asking what happened before the big bang. Kind of asking who were you before you were born. Since there was no time ticking for you, there was no you. As Saint Augustine cleverly said some 16 centuries ago, space and time came into being with the cosmos. No cosmos, no space and no time.
If only it were so simple.
Some speculate that our Universe is just a chunk of a much larger (how large?) entity, a multiverse that represents all possible realizations of universes. Or almost all. In each of them, the laws of nature may be different, and most would blatantly fail to become anything interesting. As in no life.
So, give thanks to our universe, the one among the many that has the right properties to live long enough so that galaxies and stars can form, and then planets and, in some of them, life.
But wait! Don’t get carried away. Our universe couldn’t care less about life or about preserving it. Be suspicious of arguments that claim that our universe is just right for life!
Just look at our cosmic neighbors, barren worlds, desolate and fascinating. Strip away our thin atmosphere, our protective magnetic and ozone shields and Earth would turn barren too, a dead world incapable of harboring life. (Or at least complex life. Maybe simple life is resilient enough to survive in very extreme conditions.)
So, it’s not really to the universe that we should be giving thanks but to Earth itself, our amazing, life-bearing, life-preserving planet. The more we move outwards to explore other worlds, the more remarkable our own becomes. We should all, collectively as a species, be giving thanks to our world. Most of all, for its patience in taking so much abuse from us and still letting us stick around. Few mothers would be this patient.

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Will humans figure out what is fueling my fast expansion?
I love the name they gave to it, “dark energy,” as quaint as their notion of time. I hope they won’t get carried away by giving it a name and attribute to it properties it doesn’t have. They did this with space and time, these two inventions to describe distance and change. They need concepts to organize their thoughts, certainly. But to make those concepts into real things can be confusing. As when they say that space is expanding or time is ticking away and take these things literally. Nah, these are just ways to organize measurements, nothing that exists on its own. But I have confidence they will see all of this in due time. When they figure out why I’m expanding fast now and what is this thing they call dark energy, some of these mysteries will be cleared up. Only, of course, to give rise to new ones. Meanwhile, I’ll keep expanding, creating and destroying worlds, to my great enjoyment and, of course, to that of humans. After all, let me be frank. Even I am an invention of their minds. We are all in this together.

Peering At The Edge Of Time: The Enigmatic Black Holes

by Marcelo Gleiser

Recently, scientists announced a remarkable discovery: using the NASA X-ray Observatory Chandra, they were able to find a young black hole, the youngest ever found, still reeling from its birth throes. On a personal note, it’s nice to see that the study is led by Daniel Patnaude from the Harvard-Smithsonian Center for Astrophysics, who is one of our own freshly-minted Ph.Ds from Dartmouth College: young astrophysicist finds his peer in the sky.
The object belongs to galaxy M100, at approximately 50 million light years from Earth and hence not exactly around the corner. This means that the light (or better, X-ray radiation) collected by Chandra’s antennas left the black hole 50 million years ago, about the same time that dinosaurs became extinct here on Earth. (That happened about 65 million years ago.) As aptly explained in NASA’s web site, it’s like cabling a photo of a baby to a far away place. The photo shows the baby, but it took a while to get to its destination.
The black hole, it’s inferred, is the remnant of a giant star, some 20 times more massive than the Sun. To see one just forming is incredibly exciting; no object is more mysterious than a black hole, where our much beloved notions of space and time cease to make sense.
  Black holes challenge the boundaries of the reasonable. You can picture them as a secret protected by a spherical cocoon, which we call the “event horizon.” Just like with a beach, where the horizon delineates the limit of what you can see, the event horizon marks the point of no return: if you pass beyond it, you cannot come back out. Not even light, which explains the famous name, black hole.
Now, what does go on inside the horizon? Good question. Black holes come in different kinds, classified by their mass and rotation. A simple, non-rotating black hole has a point singularity in its center, a point where, yes, the laws of physics as we know them break down. This explains the excitement: inside the horizon there is a world beyond this one where what we know of reality doesn’t make sense any longer. And we want to see more than we can.
Picture this: you shoot your worst enemy down a non-rotating, spherical black hole. He travels in a spaceship that has a blue blinking light that blinks at every second. What do you see, safely from a distance? As your enemy’s spaceship approaches the horizon, the color of the blinking light changes gradually down the colors of the rainbow, from blue to red. Eventually, you won’t see the light any longer, as it gets stretched into longer wavelengths: infrared, microwave, radio. Also, the interval between the blinking increases. Once the spaceship crosses the horizon, the blinking essentially freezes: for you, time at the spaceship has stopped! Kind of frustrating, because you won’t see your enemy’s fate within the horizon. But you do know that the gravitational pull is so intense that just the difference from the tip to the bottom of the spaceship will force it to thin out like spaghetti. You feel a tinge of remorse. (Readers who want to know more can consult my book The Prophet and the Astronomer, where I discuss dying stars and black holes in great detail.)
The shifting of light to longer wavelengths is called “gravitational redshift.” (Not to be confused with the cosmological redshift from the expansion of the universe.) The slowing down of the blinking illustrates “time dilation”: the stronger the gravitational pull, the slower a clock ticks. At the horizon, a clock wouldn’t tick any longer. Black holes are indeed quite weird.
And what would your enemy see? Well, for him, all would proceed normally; as he is freefalling into the hole, he won’t feel time dilation or light redshift. But he will feel the differential pull of gravity and be stretched into oblivion. The only other curious thing he will feel as he crosses the horizon is that he won’t be able to escape the singularity. Just as in our lives time marches forward inexorably while we have the freedom to move in any direction of space, once you cross the horizon the roles of time and space are reversed: there’s only one direction of space, directly toward the crushing singularity at the center, where gravity becomes infinitely strong.
Or so we believe. The problem is that as we approach the singularity, the theory we use to describe black holes, Einstein’s general theory of relativity, breaks down. We need a different theory, capable of dealing with absurdly huge gravitational attraction in extremely small distances. That is, we need a theory of quantum gravity to understand how strong gravity behaves at very small distances, a theory we still don’t have.
What we do know, from the first intimations of such theory, is what Stephen Hawking called black hole evaporation: it turns out that black holes are not eternal. They evaporate slowly, losing their masses due to quantum effects. In fact, a black hole is not really black for this reason: as it evaporates, it emits radiation of a certain temperature, the Hawking temperature, roughly T = (10²³kg/M)K, where M is the mass of the black hole in kilograms and K is the temperature in the Kelvin scale. (1 Kelvin = -273 Celsius. Sorry for the formula, but I’m sure some readers will appreciate it.) For comparison, the Sun’s mass is roughly 10³⁰kg. So, a black hole with the Sun’s mass would “shine” with a temperature of 10^-7K: very very cold! But note that the temperature increases inversely with the mass: a small black hole closer to the end of its life would brighten up!
Which leaves us with an intriguing question. As a black hole evaporates, its horizon shrinks. What happens as we reach the final singularity? Would the horizon disappear revealing a point where space and time are balled-up to infinite density? This does sound a lot like the Aleph of Jorge Luis Borges’ brilliant homonymous short story. We don’t know. There is something called the cosmic censorship conjecture, which says that a “naked singularity” is impossible: something will happen before things get to that pornographic all-revealing point where physics breaks down. But what? Good question. Some, including this author, have conjectured that as the black hole approaches the singularity, it will excite the extra spatial dimensions where superstrings are supposed to live and the singularity will actually disappear in a puff of strings. Wild stuff. But this was in the days when I was much more convinced of the reality of such unifying theories than I am now, as readers of my book A Tear at the Edge of Creation know well. Meanwhile, black holes remain puzzling and fascinating to scientists and non-scientists. Any new information we have on them, such as the news from Chandra, is most welcome.

Before the Big Bang? Not Yet.

 

by Adam Frank

What happened before the Big Bang?

There is a growing list of possible answers to that question ranging from "nothing" (literally) to "many repeating cycles in an endlessly cyclic Universe".
Recently Roger Penrose (one of the most distinguished mathematical physicists of our age) and a collaborator Vahe Gurzadyan claimed to have found evidence for a Pre-Big Bang Universe.  They pointed to "rings" of structure embedded in the Cosmic Microwave Background which is fossil radiation left over from the Post-Big Bang Universe.  It was an exciting announcement.  Today it seems the wind is out of their sails.
Two groups have published a response to the cyclic Universe paper showing that Penrose's effect was nothing more than a statistical fluke.  As one of the papers puts it,

Gurzadyan and Penrose have not found evidence for pre-Big Bang phenomena, but have simply rediscovered that the CMB contains structure.

I am sure the story is not over yet. Gurzadyan and Penrose are unlikely to just fold up their tents and go home.  On the other hand getting beyond (or before) the Big Bang is not going to be easy.  So stay tuned kids.  There may be more Universe out there yet.

The process of star formation

The process of star formation is one we still don't understand very well. Here is a beautiful simulation of an initially turbulent interstellar cloud of gas collapsing to form many stars. The simulation, by Matthew R. Bate, Ian A. Bonnell, and Volker Bromm lets the gas turn into stars and then follows their motions.  The stars are the little dots.

Space Travel Will Always Be Dangerous, And That's OK

 

by Adam Frank

Getty Images The Columbia lifts off from Florida on January 16, 2003. Damage incurred during the ascent into space resulted in the shuttle's disintegration during its return on February 1.

At some point we will stop collectively mourning those who die in space. As horrible as it sounds, that will be an important day for our future in space.
Eight years ago today the space shuttle Columbia was lost with her crew during reentry into the Earth's atmosphere. Twenty-five years ago the space shuttle Challenger and its crew were lost during its launch into Earth orbit. As we look back on these anniversaries we remember the horror and national sense of grief. As a nation we rightfully continue to celebrate the crew of both spacecraft as national heroes.
The dangers of space travel remain daunting. From being blown out of Earth's deep gravity well on oversized roman candles, to spending weeks orbiting in the hostile, airless, radiation-drenched environment of Earth orbit, to the terrifying plunge at Mach 25 through the atmosphere; to be an astronaut demands the deepest kind of courage.
So why, as a nation, would we ever stop honoring the next generation of heroes who perish in space? The answer has everything to do with our real future in space. The future NASA and its private rocketeer partners are hoping to build. There is a transition waiting up ahead of us. If we successfully make it across, then we will truly have become a space-faring race. But it will come with a price.
  Back in the 1980s NASA circulated a poster showing a shuttle rising off the launch pad on a pillar of flame. The title read, "Going to Work in Space." The idea was the shuttle was making access to space routine, just another day at the construction site. The truth, as we all discovered after the Challenger disaster, was that there was nothing routine about shuttle missions. Every launch carried relatively high probabilities of failure. We simply had not yet reached the point were going into space was just another day of work.
At some point, however, we may well be there. When that happens we are going to have to expect accidental deaths in space. Every dangerous profession holds this possibility. The construction of the Brooklyn Bridge — the technological marvel of its day in 1883 — took 27 lives, including it's designer John Roebling. Many more workers were seriously wounded, including Roebling's son Washington.
If we are to build an orbiting infrastructure, allowing Earth orbit to become an new domain of human enterprise, then there will have to be many space suited men and women involved. Some of those intrepid workers are bound to be claimed by the endeavor.
If we then are to use that orbiting infrastructure and take the next steps to claim other worlds in the solar system then, without a doubt, more lives will also be lost.
If we are to have a real future in space, each of these future accidents will have to shrink in scale. They can no longer be national horrors. They will have to shrink to the level of personal or community tragedy.
We have our toes in the water of this new world. Companies such as SpaceX and Virgin Galactic are beginning their push beyond the thin blue vail of the atmosphere. It will be a delicate march forward for these companies in their work with NASA. The grand push for space will meet the imperative for profit and run straight into the absolute demand for worker (i.e. astronaut) safety.
But sooner or later accidents will come. We will have to expect it. We must forever honor the heroism of our national astronauts who opened the doors of space for the entire human species. At some point in the future, however, astronauts will really be going to work in space. At that point everything will change. How we manage that change will say much about where we are in our progress towards the high frontier.

WHO PUT THE MOON HERE?

Can Life Exist On Rogue Planets?

 

by Adam Frank

Underneath, they're not so cold.
Rogue planets with frozen surfaces may have liquid oceans beneath that could support life.
Scientists believe a subsurface ocean is most likely present on Europa (above), one of Jupiter's moons.

NASA/JPL/University of Arizona/University of Colorado

Underneath, they're not so cold. Rogue planets with frozen surfaces may have liquid oceans beneath that could support life. Scientists believe a subsurface ocean is most likely present on Europa (above), one of Jupiter's moons.

Here is a link to an interesting paper from the astro pre-prints archive. It's likely that the process of planet formation is a messy affair with newborn worlds being kicked into deep space by gravitational interactions with their siblings. What happens to these planets after they are orphaned?
The authors Dorian S. Abbot, Eric R. Switzer argue that even though these worlds will wander forever in the frozen depths of space, they might still harbor life. Taking a cue from Europa, the frozen ocean moon of Jupiter, they claim

"a rogue planet could maintain a liquid ocean under layers of thermally-insulating water ice and frozen atmosphere as a result of geothermal heat flux. We find that a rogue planet of Earth-like composition and age could maintain a subglacial liquid ocean if it were ~3.5 times more massive than Earth. If a rogue planet had about ten times higher water mass fraction or a thick cryo- atmospheric layer, it would need to be only ~0.3 times the mass of Earth to maintain a liquid ocean."

These dark space planets might even be found if they came close enough to the solar system. "Such a planet could be detected from reflected solar radiation and its thermal emission could be characterized in the far-IR if it passed within 1000 AU of Earth." That's about 1000 times the distance of the Earth from the Sun.