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Fate of the Universe

Fate of the Universe


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Which scenario will be worse for the ultimate fate of the Universe, forever expanding or the "Big Crunch"? Will the Universe be destroyed in both scenarios? At the present time does it appear that it will expand forever or will the expansion stop sometime in the future?


I'll be brief in my answer but I suggest you look at the wikipedia page on dark energy for a good starting point for further research. (http://en.wikipedia.org/wiki/Dark_energy)

At the present time it is believed that the universe will continue to expand at an ever increasing rate due to the driving force of "dark energy" (which is as mysterious as it sounds!). Since space itself is expanding there is no limit to the rate of change in the distance between them, and it is quite possible this speed exceed that of light - meaning observers at each point will not be able to see each other.

With this in mind, eventually (in many billions of years) the universe will be expanding so fast that we will not be able to see any other galaxies, and eventually any other stars after much more time has passed. If the acceleration continues at the increasing rate Earth and the Sun will be "pulled" apart, and at this point the situation on Earth is pretty bleak - no Sun, no stars and no external light.

In the extremely far future it is possible the acceleration of space will cause Earth itself to be torn apart, and the eventual fate of the universe is for every molecule, atom and particle to be broken apart until all that remains are stray photons.

So that's a pretty bad scenario as far as the ultimate fate of the universe goes, but at the moment it seems like that is what may happen.

It's very important to note that extending the increasing rate of acceleration into the future that far is not good practice and probably won't provide very accurate predictions.


Which scenario will be worse for the ultimate fate of the universe?

Well, that's a wee bit opinionated. It depends on your point of view - that is, how you take a liking to the following two scenarios. Everyone has their own opinion; from the details I give below, I'll let you answer that yourself.

To infinity - and… well, more infinity: The perpetually expanding universe

There are actually three types of universes that could fit this model: The accelerating expansion one, the constant expansion one, and the decelerating expansion one. At this point in time, we appear to be in a universe undergoing accelerated expansion, thanks to dark energy. However, all three scenarios give us a similar end result: A dead universe.

In the far future, as long as the universe does not curl back into a Big Crunch, slowly all processes as we know them will begin to end. Star formation will eventually cease, and black holes will slowly start to gobble up a lot of matter. In the even farther future, black holes are evaporate to decay via Hawking radiation, leaving the universe a collection of various subatomic particles. (If protons decay, then perhaps there will no longer be any atoms). The temperature of the universe will drop until everything is about thermodynamically equivalent. Not a great place to be (well, there won't be any life, so nobody will be around to see it, but still… ).

Beyond this… well, there are a few different ideas regarding what could happen. The Big Freeze idea states that the universe will eventually just cool off to this low-temperature state. The Big Rip idea says that matter itself could be torn apart bye extreme expansion of space. Cosmological false vacuum theories suggest that quantum tunneling effects could make some interesting expansion possible. However, I emphasize that we do not know whether any of these long-term theories are correct. They are too far in the future, and there is too much uncertainty among the relevant factors.

In the short term, however, it appears our universe will expand forever.

Back to the beginning: The Big Crunch universe and all its friends

The Big Crunch scenario says that if the density of the universe is greater than the critical density, the universe will fall back onto itself into a singularity - just like the Big Bang. This leads to other theories, such as the epykrotic universe, or a Big Bounce, which postulate that our current universe is just undergoing one of infinitely many stages of expansion and collapse.

This isn't exactly a great outcome, either, but again, I'll leave you to judge.


Fate of the Universe - Astronomy

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An introduction to modern astronomy's most important questions. The four sections of the course are Planets and Life in The Universe The Life of Stars Galaxies and Their Environments The History of The Universe.

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Great teacher! Extremely interesting lessons. The teacher was able to explain very complicated aspects in physics to non specialists audience in an intriguing manner. Thank you!

Easy to follow. Anyone who is interested in Astronomy should take this course. This course is better than the course (Astronomy - Big Questions) that I took at my University.

What is the Fate of the Universe?

The History of The Universe - Why the Big Bang? A History of Time, What Happened Before the Big Bang

Преподаватели

Adam Frank

Текст видео

Welcome back everyone. So to answer this question that is, we're obsessed with this week about the fate of the universe, we first have to understand the idea of the Big Bang. And why we even consider the Big Bang to be true. So let's start with the most important the first piece of evidence that lead to our thinking about the Big Bang, which is what's called Hubble's Law. Recall from our first week, the idea of Doppler shift, that if we see light from an object being having its light stretched, so that it be if we have something that we know the wavelength, what the wavelength should be, and we see that wavelength stretched out, we know that that is a redshift, and the object is moving away from us. If the light is compressed, and the wavelength goes down, that is a blue shift, and the object is heading towards us. Well, it was in the 1920s that Edwin Hubble went out and started making measurements of redshift or blue shift of galaxies, and what he was astonished to find was that everything was redshifted. With the exception of just one or two cases, every galaxy he looked at was moving away from us and so all the galaxies were moving away from us. And not only that, the speed at which the galaxy was moving away from us depended on how far away it was from us. So by making independent measurements of distance and combining that with the measurement of the galaxy's redshift he found what was called a linear relationship. The farther away it was, the faster it was moving, and that's called Hubble's Law. And this was one of the most remarkable discoveries in the history of astronomy, because what it implied was is that the entire universe was expanding. Not just the galaxies, but space-time itself was actually stretching and the galaxies were just sort of like you can imagine them to be marbles pinned onto a rubber sheet and as the rubber sheet was stretched, the galaxies are just going along for the ride. So this was the first indication essentially that the universe was expanding. That there was a, something we could call a Big Bang. so, you know, if you imagine putting raisins inside a loaf of raisin bread that you're or, you know or, dough. And then putting it in the oven and allowing the bread to expand, because, you know, of course, of the yeast. Every raisin will move apart from every other raisin. So, no matter which galaxy you're sitting on, you would see all the other galaxies moving away from you. So, this was our first indication that something like expan, or that the, the, it was our first indication that the universe was expanding, right. So where do, how do you get a big bang from this. Well, if you run the movie of the universe's expansion backwards, then what youɽ expect is over time, things that are very far apart would end up being very close together. So it was clear from this, well it wasn't exactly clear, we took a, a, few more pieces of evidence for people to really understand this. But at least the implication with the discovery of the Hubble Law was that the universe early on must have looked different than it does now. The universe was not static, the universe was not eternal in its appearance, that there was an earlier epoch of cosmic history that was very different from our own. So using Hubble's Law, you can actually figure out in a simple way that time that it would take for everything to be very close together, and what you end up with is the naive use of Hubble's Law. You end up with a cosmic age of about 14.3 billion years. That exhumes, well, there's, there's in that, it, that calculate, it's a very simple calculation. As we'll see, that's not the actual age of the universe, but it's pretty close. So even a simple calculation gives you ten, about 10 billion years of cosmic history. What comes with the understanding that the universe has evolved, is that if we look at a galaxy 7 billion light years away, we're really looking halfway back to the beginning of the universe. Right, that's what's really remarkable. Once we come to understand that the universe has a history, when we're looking back in, when we're looking out in space, we're actually looking back in time and history. So that's the, that's what comes when we understand that the universe is not static. Alright, so the idea of the Big Bang is that the universe started from a hyper compressed state. That all the matter in the universe, was densely packed. Now to understand what this means, we have to go through, we have to understand what the Big Bang is, and what it isn't, okay? The first thing is, the universe the Big Bang is not a theory of how the universe began, how time began. It's a theory about what happens immediately after the universe began. It's a theory of after, because we're going to use the laws of physics that we understand, and we're going to track as far back into this hyper compressed, hyper, high temperature state as we possibly can. And then let time begin to run forward. But what actually happened when the universe, what actually created that state of the universe, is not science. Right now we can't answer that question. Maybe we will be able to soon, but right now we're not in a position to really answer that question definitively. So the Big Bang is a theory of what happened after The Big Bang. It also tells us how the universe evolved. It didn't tell us why the universe is there. Right, again, so this is, you see with cosmology how this is a science that's really bumping up against very deep philosophical issues and if you're so inclined even theological issues. Okay the Big Bang is our creation story right, it's our narrative of how the universe evolved and emerged to become what it is today. And it's still, because it's a scientific story, we see changes in it. the, the basic narrative has not changed now over 60 years. Our understanding of what immediately happened after the moment of creation, has not changed. But, you know, we've been adding to the story as we come to understand more more more facts. So, we have really firm observational evidence for a lot of this story, but when people begin talking about what happened before the Big Bang or or, or, your know, the idea that there is multiple universes, that stuff is still very much scientific speculation. We don't have any evidence for the existence of any other universes, or we don't have any evidence for, yet for what came, direct evidence, for what came before the Big Bang. So it's important to understand where the science is very firm, and where scientists are still, you know, try, you know, coming up with new ideas and hoping to find something that might have an observational handle on it. Okay? [BLANK_AUDIO]


194 Questions Regarding the Eventual Fate of the Universe

There is nothing whatsoever that we have measured, or can measure, that will show us anything about this larger space. Everything that we measure is within the Universe, and we see no edge or boundary or center of expansion. Thus the Universe is not expanding into anything that we can see, and this is not a profitable thing to think about.

Will the Universe keep expanding, come to a stop, or begin to collapse?

This depends on the ratio of the density of the Universe to the critical density necessary to support continued expansion. If the density of the Universe is higher than the critical density, the Universe would recollapse in a Big Crunch . But current data suggest that the density is less than or equal to the critical density so the Universe would expand forever.

Even if the Universe continues to expand, what will eventually happen to the Universe?

From our current knowledge and understanding, the Universe will continue to expand. Matter will be converted to energy. This is understood from the Laws of Thermodynamics: matter cannot be created out of nothing the Universe would undergo the conversion of its matter to energy. Finally, with matter converted into energy, eventually the Universe will become dark. This would happen in about 100 trillion years!

Astronomers believe Dark Matter and Dark Energy exist. If so, why can’t we see either?

Probably because our sensors cannot register Dark Matter and/or Dark Energy. Yet every time scientists turn a higher fidelity instrument toward the Universe, they find something new. Consider this as a science history lesson: we didn’t see individual cells until the microscope was invented and scientists theorized about the atomic nucleus now we see the parts of the nucleus.

What of Parallel Universes or Multiverses?

Some current thinking points to the possibility of numerous universes, of which we are in one universe. Think of our Universe as a bubble now, think of multiple bubbles. Is there any evidence? Yes, what appears to be “bumps” in our bubble. These bumps appear in the Cosmic Microwave Background images. It has been hypothesized that the bumps represent distinct collisions between Universes (December 2010).


The End of the Universe: What is our ultimate fate?

By: Maria Temming July 18, 2014 0

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Image of the temperature fluctuations in the cosmic microwave background created from 9 years of WMAP data.
NASA / WMAP Science Team

During the latter half of the 20th century, cosmologists determined that there were three possible scenarios for the end of the universe, and they all depend on its density. If the density were high enough, then gravity would eventually slow the expansion of the universe and cause it to re-collapse in a “Big Crunch.” On the opposite side of the spectrum, a low density would allow the the universe to expand forever. Everything would gradually dim, cool, and spread out in a fate known as the “Big Freeze.” But if the density were just right, then the universe’s expansion would very, very gradually slow down, coming to a complete stop only after an infinite amount of time. This third picture is known as a “flat” universe, and would also end in a Big Freeze.

Images of the cosmic microwave background, relic radiation leftover from the Big Bang, show a universe whose density is very close to the critical density of the latter scenario. So theoretically, the expansion of the universe should eventually stop, right?

Not according to observations first made with the Hubble Space Telescope in 1998. These observations of supernovae in distant galaxies indicate that the universe is expanding at an ever-increasing rate. Cosmologists explain this startling observation with dark energy, a mysterious force that appears to counteract gravity’s pull, instead accelerating the universe’s expansion. The nature of dark energy is one of the most pressing questions in modern cosmology — answering it would provide new insight into the fate of the universe. In one scenario, where dark energy’s negative pressure increases over time, the universe would ultimately rip apart.

Regardless of whether this Big Rip scenario actually takes place, we do know that accelerated cosmological expansion will ultimately carry other galaxies out of our view.


Fate of the Universe - Astronomy

Great teacher! Extremely interesting lessons. The teacher was able to explain very complicated aspects in physics to non specialists audience in an intriguing manner. Thank you!

Easy to follow. Anyone who is interested in Astronomy should take this course. This course is better than the course (Astronomy - Big Questions) that I took at my University.

Преподаватели

Adam Frank

Текст видео

Welcome back everyone, and welcome to the last week of our course. And so today we ask the big question. What is the Origin and Fate, in particular the fate, of the Universe. So this is a really old question, in fact it's probably one the oldest questions that we have. Every culture has its creation story, its creation myth. And these questions always ask, where did we come from? And you know, where are we going, right? Where is, what is humanity's place in the universe but more important, where did the universe originate from? And so every culture and religion has one of these stories and those stories are usually built from ideas that mirror the kind of geography that you're experiencing, the kind of conditions you're experiencing. So you know, desert cultures tend to produce sort of deserty kinds of stories. And you know, rich tropical cultures tend to produce stories that have you know, reflect the kind of lives that they're living. So but there's also an equally interesting question which is, you know will the universe last for ever? How does the universe end. So that's really where we're headed towards. But in the process we're going to have to ask, ask the question of how did the universe begin. So it's interesting you know, we're all familiar with in the West, with this story, the Biblical story of Genesis, in the beginning God created the universe. You know, let there be light, et cetera. So you know, we're very much familiar with that one. But it's important to understand that these different versions of the creation story have they're different, imaginative responses to this question. So, in the West we have this idea that there was nothing, and then there was light. And the universe began. But for example in the Hindu cosmology, the universe is an endless cycle of birth and death. So for example, the god Indra speaking in the Brahma Vaivarta Purana is, speaks, thinks of himself as being the supreme deity but then is sort of, you know, schooled out of that. Where you know, one of the characters says, out of the pore of the body of Vishnu, a universe bubbles and breaks. Will you presume to count them? Will you calculate the gods in all those worlds, the worlds presents and the worlds past? So, this endless cycle of universes is something that the, the Hindu cosmology understood and remarkably, you know, there's some ideas in modern cosmology that say oh yeah there's actually a cyclical universe. So, you know, there was an imaginitive response to this question that dates back to our beginnings as culture, and then there's the scientific response and the scientific response also pulls from the imagination, but of course it has to work with the data. And that's what makes cosmology, scientific cosmology, different from the narratives, the creation narratives, from myth and religion. And so what we're going to look at this this week, is the scientific narrative of cosmology and how we believe why, or why and how we believe that this narrative actually has you know, a great deal of truth to it. so, let us go on from there. So the question really that we're interested in, we're going to be asking, are going to be, how did the universe begin, what is the evolution of the universe, and how do we think the universe is going to end. [BLANK_AUDIO]


Fate of the Universe - Astronomy

What is the mass of the Universe? Also how can you prove that this is the true mass of the Universe?

As nobody knows the size of the universe, one cannot really talk about the mass of the universe, though one can talk about the mass of the observable universe. What is normally sought after is the density of matter in the universe (which is the mass per unit volume). This is what is important in determining the fate of the universe: whether it will collapse one day or whether it will continue expanding forever.

The density of matter in the universe can be measured by various means, which are too technical to go into at this point: people measure the density by studying the fluctuations in the Cosmic Microwave Background, superclusters, Big Bang nucleosynthesis, etc.

According to these studies, the density of matter in the universe is about 3 x 10 -30 g/cm 3 , which means that it is 300 billion billion billion times less dense than water. Note that this includes the contribution of dark matter and so the density of luminous matter (that we see as stars and galaxies) is only about one-tenth of the figure given above.

Now, the size of the observable universe is about 14 billion light years, and using the above value of density gives you a mass (dark and luminous matter) of about 3 x 10 55 g, which is roughly 25 billion galaxies the size of the Milky Way.

This page was last updated June 27, 2015.

About the Author

Jagadheep D. Pandian

Jagadheep built a new receiver for the Arecibo radio telescope that works between 6 and 8 GHz. He studies 6.7 GHz methanol masers in our Galaxy. These masers occur at sites where massive stars are being born. He got his Ph.D from Cornell in January 2007 and was a postdoctoral fellow at the Max Planck Insitute for Radio Astronomy in Germany. After that, he worked at the Institute for Astronomy at the University of Hawaii as the Submillimeter Postdoctoral Fellow. Jagadheep is currently at the Indian Institute of Space Scence and Technology.


September 30th: Encore: Broken Teeth and the Fate of the Universe

Description: Learning about cosmology is full of surprises, and sometimes those can be as terrifying as suddenly losing a tooth.

Bio: Ben Lillie is a physicist who left the academy for the wilds of New York’s theater district. He now writes and performs stories about science and being a scientist.

Today’s Sponsor: No one. Please consider sponsoring an episode of 365 Days of Astronomy by clicking on the “Donate” button on the lower left.

This is the 365 Days of Astronomy Podcast for March 24th. My name is Ben Lillie. I’m an ex-particle physicist, now living in New York City where I write and tell stories about science. You can find some of my work online at peculiarvelocity.com. For the podcast today I’m going to tell one of those stories.

It’s never clear what should be surprising, almost by definition. The entire Universe is expanding, every galaxy is moving away from every other galaxy. This means that in the past they were closer together, and in the distant past there was a beginning, a big bang. It feels like this should be surprising, but it isn’t. What’s surprising to me is the end of The Universe.

As the universe expands after the big bang the gravity of every bit of matter — every galaxy, every star, every tooth in every head — pulls on every other bit, and this pulling slows the expansion. There are two possibilities for how it can end: if there’s enough matter, the pull is strong enough to slow the expansion to a halt and then to start collapsing, and the universe will end in a big crunch. If there isn’t enough matter then the expansion will go on forever, always slowing down but never quite stopping, coasting into infinity.

Or at least that’s what people thought in the fall of 1998 when I was a sophomore physics major taking a road-trip with some friends to Ashland, Oregon. We were there to see the Oregon Shakespeare Festival, and take in the sights. In Ashland, the sights are pretty much the sulfur springs. They smell like sulfur, and that’s why they’re famous.

So, after a play, we were sitting out in the park around the water fountains where you can taste the sulfur water if you’re insane, sitting on a bench, chatting in the shade, and I noticed a little hard thing in my mouth. I spit it out and it was white, and jagged on one side, and then I noticed that the edge of one of my molars was sharper than it had been. And then I realized that quietly, without any fuss, by tooth had broken.

Now, I could imagine several ways to break a tooth, but they generally involved an object, say a fist, moving very quickly towards one’s face, or perhaps one’s face moving very quickly towards an object, say the ground. Teeth do not break while you’re just sitting there, talking to friends. But that’s what happened.

As soon as I realized that, I freak out. How did this happen? If it happened once, could it happen again? Look, I brush I floss this should’t happen! I panicked. I was confused. I was nauseous, and the sulfur smell was not helping. Luckily I didn’t throw up, but only just.

Eventually I calmed down, and I called my mom to tell her about it, and she said “Oh yeah, we knew that might happen.” I and went “What? You knew? And you’re calm about it?” It turns out that when I was very young, when my adult teeth were just forming, I was sick with a very high fever, and that fever disrupted the tooth formation and made them especially brittle. It was good to learn, if a little annoying because I would have to go to the dentist a lot more often for preventative work. But now at least I knew, and somehow I guess at least I’d learned something about myself.

A couple days later, home from the trip, I had the dentist fix it. While I was recovering — which is to say later that afternoon while I was sitting on my couch still briefly hopped up on Novocain — I started reading about the “Discovery of the Year” in Science magazine. Two teams of cosmologists had set out to measure how much the universe was slowing down, to measure something called the deceleration parameter. If this parameter is greater than a half, then the universe will collapse less than a half and it expands forever. What they found, and the reason it was a breakthrough, was that the deceleration was negative. It’s not slowing down at all it’s speeding up. The universe is accelerating.

We don’t know why. People’s best guess was that space is filled with a pervasive energy — the same amount at every point in space, and this constant energy density pushes everything apart. This is called the Cosmological Constant, and 12 years later it’s still our best guess for what’s causing the acceleration.

I had no idea what to make of this, so I took it to my hero of the moment: Rick Watkins. Rick was the professor for my sophomore physics survey, and he was amazing: young, wiry, an ultimate frisbee player, he could make thermodynamics funny, make quantum mechanics trivial and could grow a decent-looking beard.

He explained it was a good result and it was probably correct. He explained about the Cosmological Constant, but as he did I thought: “Look, if there’s a constant energy at every point and the universe is getting bigger, then that means there’s more energy as time goes on. So it can’t be right, that violates the law of conservation of energy.”

And he said, “So? Energy isn’t conserved in an expanding universe anyway.” Now, that was a surprise.

Conservation of energy is one of the most sacred principles of physics. Energy can be moved from one from to another: kinetic to potential to chemical to heat to mass. It can be swapped between these forms, but the total amount remains constant. Energy can neither be created nor destroyed. You learn this very early in your education, and you quickly realized how powerful of a principle it is problems that seemed intractable melt away when energy conservation is invoked. It becomes the central element of how you see the world of physics — so central that it becomes like air, all around but unseen, it’s use becomes like breathing, an autonomic response. Breath in, see physics problem, breath out, drink coffee, write down the law of energy conservation, breath in, chew food to a physicist, those all happen without thinking.

And yet here was Rick, my hero, telling me it didn’t apply in this case. I made him show me the math, and he did, and he was right. Simply put, if the space itself is changing, then the definition of energy is changing and it doesn’t have to be conserved. It’s a tiny effect. For anything that any human will ever do, it may as well be conserved. We’ll never get useful energy out of this. You would need to connect galaxies across the visible universe to see any violation of the law, but it’s there.

And just as using energy conservation was like breathing, discovering that it wasn’t always correct was like suddenly discovering that I wasn’t breathing, or that my heart had stopped beating, or… or that I’d suddenly broken a tooth. And just as when the breaking happened, my mind exploded in that painless agony, and those same emotions began to well up the panic, the confusion, the nausea. But this time, in the middle of that mental storm, I looked up and saw Rick grinning at me, and I realized that he thought this was great. He loved it, he thought it was wonderful.

And I realized that it is. The thing that made the law of conservation of energy so amazing was not the law itself, but the fact that it describes reality, and the reality is that it doesn’t always apply. That’s what’s so great about science no matter what is discovered, no matter what hallowed principle is overturned, the discovery is always fantastic because we know more about nature.

I find this example particularly great, and not just because I had such a huge and absurd reaction, but because few things are considered as fundamental or as immutable as the fact that energy can neither be created nor destroyed. There are things we know extraordinarily well, things we can say we are almost certain of, but that word “almost” is important. If even the law of conservation of energy can fail in certain circumstances, what other unthinkable things might be true?


What is the Ultimate Fate of the Universe? And how do we know?

I have an upcoming Astronomy Final and I have been searching an answer for this, but I cannot seem to find one, I have found a lot of theories, but I want an answer that is complete and is recent because our understanding of the Universe has evolved tremendously throughout the years and I don't want to end up with an outdated theory/thinking.

Please help! And thank you to all the do!

the most recent popular theory is what I've heard some people call colloquially 'the big freeze.' Essentailly, because the universe is still accelerating in its expansion, (mediated by ⟚rk Energy'), eventually, everything will get to be so distant from each other that everything will have lost all functional visibility. So everything that's within the visible universe will have red shifted towards the limit as it approaches a wavelength of no energy. The end result of this will be, for a period of time, there will be pockets of mass/energy, for which gravity was stronger than dark energy on those objects - enough to hold them together. They would eventually all coalesce into a blackhole, and die off by hawking radiation, leaving just speckles of radiation throughout the now dark universe.

This is all obliviously just extrapolation from the observation that the universe is still accelerating in its expansion due to ⟚rk energy' - which no one really has any idea about. So until we understand what dark energy really is, we won't really have a sold theory, other than just a well educated guess.


Seeing fate of the universe is astronomy's goal, Ridgefield scientist says

When astronomer Heidi Hammel looks to the sky, she sees the possibility of mapping the future of mankind.

A senior research scientist and co-director of research at the

Space Science Institute in Bolder, Colo., Hammel lives in Ridgefield and telecommutes to the institute.

She has been instrumental in Ridgefield's involvement in the 2009 International Year of Science, which celebrates the 400th anniversary of Galileo first using a telescope.

"Why do astronomy?" Hammel asked the crowd at Thursday's "Rise and Shine" breakfast hosted by the Ridgefield Chamber of Commerce

How that expansion will continue and if it will finally come to an end is a primary question astronomers ponder.

"We now know the universe is going faster and faster as it's growing," she said. "We know this from our studies of exploding stars."

It is now believed the universe is made up of 73 percent dark energy and 23 percent dark matter, and only 4 percent of it is stars, planets and galaxies.

But no one knows what dark energy or dark matter is, Hammel said. The concepts are only 14 years old.

"So what is humanity's destiny?" she asked.

That is what scientists are trying to determine through the study of astronomy.

Hammel mainly studies the outer planets and their satellites. When a comet hit Jupiter in July 1994, she led the Hubble Space Telescope team that investigated Jupiter's atmospheric response to the collision.

"It made plumes of gases that rose 1,000 miles high. Jupiter was covered with atmospheric soot," Hammel said. "If that impact had happened on Earth, we all would have died. It would have created a major disruption of the biosphere. This is what we think happened to the dinosaurs."

Hammel said there is no concern a comet of that magnitude will hit Earth in the near future. Nor will the asteroid Apothess hit Earth in 2032, as was previously feared it will just shave the Earth's atmosphere.

But a comet or asteroid could strike the planet at some point, so scientists study their orbits and projections.


17.12: Questions Regarding the Eventual Fate of the Universe

There is nothing whatsoever that we have measured, or can measure, that will show us anything about this larger space. Everything that we measure is within the Universe, and we see no edge or boundary or center of expansion. Thus the Universe is not expanding into anything that we can see, and this is not a profitable thing to think about.

Will the Universe keep expanding, come to a stop, or begin to collapse?

This depends on the ratio of the density of the Universe to the critical density necessary to support continued expansion. If the density of the Universe is higher than the critical density, the Universe would recollapse in a Big Crunch . But current data suggest that the density is less than or equal to the critical density so the Universe would expand forever.

Even if the Universe continues to expand, what will eventually happen to the Universe?

From our current knowledge and understanding, the Universe will continue to expand. Matter will be converted to energy. This is understood from the Laws of Thermodynamics: matter cannot be created out of nothing the Universe would undergo the conversion of its matter to energy. Finally, with matter converted into energy, eventually the Universe will become dark. This would happen in about 100 trillion years!

Astronomers believe Dark Matter and Dark Energy exist. If so, why can&rsquot we see either?

Probably because our sensors cannot register Dark Matter and/or Dark Energy. Yet every time scientists turn a higher fidelity instrument toward the Universe, they find something new. Consider this as a science history lesson: we didn&rsquot see individual cells until the microscope was invented and scientists theorized about the atomic nucleus now we see the parts of the nucleus.

What of Parallel Universes or Multiverses?

Some current thinking points to the possibility of numerous universes, of which we are in one universe. Think of our Universe as a bubble now, think of multiple bubbles. Is there any evidence? Yes, what appears to be &ldquobumps&rdquo in our bubble. These bumps appear in the Cosmic Microwave Background images. It has been hypothesized that the bumps represent distinct collisions between Universes (December 2010).


Watch the video: Στον κόσμο του σύμπαντος. Χίμικο και Όροτσι: Οι γαλαξίες τέρατα (September 2022).