Risu nodded. "Very good, everyone. Cosmology or," he added, "if one wants to be exact, physical cosmology to distinguish it from the philosophical discipline of cosmology, is the science of interest here."

He began walking up and down in front of the class as he usually did when lecturing. "Cosmology. The scientific study of the large-scale structure of the Universe and, indeed, of its possible origin and end. Last term, when discussing the history of astronomy, we spent a little time on cosmology as it really is one of the areas of interest that reach back the furthest in human history. But this term, leaving metaphysics behind, we shall focus purely on physical cosmology."

Risu stopped and looked at his class. "With this in mind, can anyone venture a guess as to when cosmology outgrew its philosophical childhood behind and became a science in its own right? And, if I might add a second question, what would or could have led to this development?"

Chloe felt a little puzzled about this question. She had an idea of what may be a rather basic answer but who knows it may be right. Thus she raised her hand and responded, "I believe when people started to learn things about the world around them that could be proven facts rather then just guesses is when cosmology became it's own science.".

Lila raised her hand and waited to be called on. "Is it either with the invention of telescopes in the early 17th centuary or with Albert Einstein's general theory of relativity published in 1915," she responded.

"Didn't scientists just think the universe was there, and had like no beginning or end." Jack started with his hand waving in the air again. "But then some other scientist said NO, and developed his own theory about it ... something to do with static and matter ... or something."

"At first people and also scientists didnt know about zodica signs and jist thought the universe was there.The word cosmology was first used 1730. With the discovery of telescopes that era the cosmolgy got science on its own", Fee wasnt sure if that was right but she found saying what you know better than just saying nothing because you were afraid it could be wrong.

Rubiey had known it was Physical Cosmology; she had read about it in the book. But what on earth was he talking about now?! Rubiey sank a little lower in her chair, and copied down what everyone was saying. Maybe she'd answer the next question..

Risu pointed at the first student to raise her arm and listened to her answer. "You are essentially correct, of course, Miss Merets," he said when the girl had finished. "I was looking for something a bit more specific to cosmology, but your point is well taken. Only substantiated guesses are workable in science."

The next student had an answer Risu was looking for. "Very good. General relativity is often considered one of the cornerstones of modern cosmology. Telescopes still had a long way to go before they became important on the grand cosmological scale in the 17th century, but, no doubt, without them some of the most important facts that are at the basis of our current understanding of the Universe could not have been, er, spotted."

"Or something," Risu said with a slight smile, hoping privately for a little more substance and less waffling in the student's homework. Although he had to admit, of course, that astronomy was very difficult work. And it was his job to teach it. "We shall return to competing cosmological models in just a minute."

"Good point about the telescopes, Miss Schwarzberg," Risu said, pointing at the young Slytherin next. "Zodiac signs, while giving fascinating insight into the ability of humans to find signs and images, are not as important to cosmology, however."

He glanced around at the rest of the class. "Miss Schwarzberg here and Miss Weasley-Schleck have both raised important points that touch on the longer history of cosmology. We will meet Einsteinian relativity again later this term, most likely, but before we go into some of the first educated guesses of modern cosmology, I would like to focus on the birth of this science in the 17th century for a moment."

Walking up and down the length of his desk again, Risu continued. "Last term we found out that the time of and following the 17th century marked the beginning of modern science. The Renaissance and subsequent Enlightenment lead to the now globally employed scientific method. Naturally enough, scientists began applying it to the Universe at large as well, but without the proper technology, none of these attempts were more than metaphysical meanderings." A smile scuttled over his face.

"Of course, the human mind is painfully unable to grasp the size and scale of the cosmos. To illustrate, perhaps, this struggle to understand, we can point out the German philosopher Immanuel Kant who was able to come up with two completely opposite philosophical..." Risu paused, trying to find the right word. "Proofs," is what he settled for. "If you will. One showed that the Universe had a beginning and had an edge, and the other 'proved' that it was eternal with no limits in space."

Risu shrugged. "Now, I am no philosopher, and the purpose of this class is not to teach Kantian philosophy, which at any rate I cannot pretend to know, but... can anyone of you speculate why he would come to two radically different conclusions? Or what his arguments might be like?"

Fee thought about it for a while.
"Maybe as he first tried to find out more about the universe the technology wasnt as good as it later had been. Cause of that his first proof couldnt be as accurate as his second."

wow, this was some confusing stuff Emmaleigh thought. but maybe, just maybe she could come up with an answer. She thought about the paradox in front of her, and then raised her hand. "C-could he possibly m-mean that the universe is eternal b-because it has always been a-around, but that it has a b-beginning because that is as far b-back as we can d-date it? And, um, that the u-universe is infinite, and the e-edge is as far as we h-have been able to s-study?" She didn't know if that was the right answer, but at least it made since to her.

Brittany was extremely lost when it came to the next question. she silently scolded herself to pay attention more because maybe she had missed a couple words or sentences of explanations.

Okay, yeah. She was officially an idiot.

She should have just listened to herself last year. Astronomy and Ellie did not mix. She couldn't remember ANYTHING, for one. And she wasn't ABSORBING anything now. Like that. That that the Professor just said. That. She had no idea. It happened, what? Like two seconds ago? And now.... she just didn't know. She just didn't.

Blink.

Risu waited for a little while to see if any other answers would be forthcoming, but there were none. He wasn't surprised. This had been a question he'd asked more or less out of the blue, to see if any of his students were that interested in 18th century rationalist philosophy to know more about Kant than he did (admittedly a rather long shot). He decided to press on quickly to reach scientific terrain that he was more familiar with.

"That seems like the most logical conclusion, definitely," Risu said with a nod. "We are, at any rate, talking about logical proofs here rather than scientific proofs which, as you should know, aren't really provable as such anyway."

Risu nodded encouragingly. "You actually add more to this question than Kant could have possibly known. As far as he was concerned, he was out to show that both ideas - that of an infinite, eternal cosmos as well as the opposite - had equal validity." He began wandering once more.

"We know more now, of course. It is generally agreed upon that our Universe, at least as it is now, has both a spatial and a temporal edge. That is, there is a border to it." He raised a finger. "With certain limitations, which we will come to. As far as time goes, standard cosmology conceives of time as having begun at the point of origin of the Universe. You should be aware, however, that the reasons for this are not at all clear. There are numerous more or less educated guesses."

Waving a hand, Risu continued, "But let us proceed onwards. As Miss Weasley-Schleck informed us earlier, one of the main driving forces behind modern cosmology is Einstein's theory of general relativity. And while his calculations predicted the kind of Universe we do find ourselves in, it wasn't until the early years of the 1920s that observational evidence was streaming in."

He grabbed his wand from the desk and waved it behind himself. An image appeared on the wall.



"This," Risu said, pointing, "is the 2.5m Hooker Telescope at the Mount Wilson Observatory in the United States. It's long defunct now, of course, but 150 years ago, it revolutionised our understanding of the Universe. It was chiefly used by a scientist by the name of Edwin Hubble. Who, if you please, was Edwin Hubble?"

I believe its because he used two different reasoning. One being sensory,what we preseve and the other logical, what we believe or think.

Lila was thrilled because she was sure she knew this one. "Edwin Hubble was an astronomer that demonstrated galaxies other than the Milky Way existed," she answered as she had her hand raised. Lila was loving this class.

"Edwin Powell Hubble was an American astronomer who profoundly showed us a new way to understand the universe by demonstrating the existence of galaxies other than our own, the Milky Way. He also discovered that the degree of "Doppler shift", also known as "redshift",observed in the light from other galaxies increased in proportion to a particular galaxy's distance from Earth",Fee said raising her hand.

Oh Brittany was excited now because she was from the united states and she had learned this in her muggle school before she came to hogwarts. She raied her hand " He was the scientist who discovered there was other glaxies besides the milky way. He also discovered something dealing with light porportions in other glaxies growing in size upon leaving from earth which became a law called Hubbles law. Thats how they found out the universe was expanding." She said with a smile. Who knew all that what she thought was useless information would come in handy now. She might enjoy this class.

He was the man who was the first to show that the universe is expanding, and is considered by many to be the father of observational cosmology. Nessa said

Emmaleigh gave a small smile. so she had been on to something. She picked up her quill scribbled some notes down on to her parchment. She looked up as the picture appeared on the wall. Hubble? she knew alittle about him. Her father loved to study the stars, it was one of his favorite ways to spend an evening out on their farm. She raised her hand to answer. "The H-hubble Space T-telescope was named after h-him. He is c-called the p-pioneer of distant stars. I think it was b-because he discovered that other g-galaxies exist."

Kurumi began to wish she had not read so much about magical creatures and had also done some reading about astronomy. She felt utterly lost for the first time - and she was not happy about it...especially when the professor said "as you learned last year." She hadn't been here last year, and almost raised her hand to point that out. She sure got agitated when she didn't know what was going on.

Oh! Edwin Hubble! Kurumi knew a little about him. She raised her hand. "Kurumi Hollingberry, first year Gryffindor," she introduced herself before continuing with her answer. "Mr. Edwin Powell Hubble was an American astronomer completely changed our way of understanding the universe by proving that there is more to the universe and more galaxies than the Milky Way Galaxy in which Earth resides. He also helped establish that the universe itself is constantly expanding. He also created a system for classifying galaxies that is commonly used where galaxies are divided into 3 broad classes - ellipticals, lenticulars and spirals - based on their visual appearance. This is called the Hubble sequence, although some call it the Hubble tuning-fork diagram." Kurumi would have to write her brothers and thank one in particular for being an astronomy nerd.

Jacqueline raised her hand. ''Edwin Powell Hubble was an American astronomer who profoundly changed our understanding of the universe by demonstrating the existence of galaxies other than our own, the Milky Way. He also discovered that the degree of "Doppler shift" observed in the light spectra from other galaxies increased in proportion to a particular galaxy's distance from Earth.''She was very nervous. She sat down and listened what others were saying.

W.O.W That thing.. er telescope was cool. It looked like a light tower though... anyways, Edwin Hubble? She has never heard of him. Who was he? Louisa looked around at her classmates and listened to their answers. There truly seemed to be more educated students than herself. Not good. She should raise her reading hours from 10 to 12. A serious nod was followed as a confirm.

Jenny blinked. Edwin Hubble? She had no idea who the guy is, but she heard of the Hubble Space Telescope before. Even then she didn't know what the Hubble Space Telescope did. She quickly wrote down some notes before reminding herself to read more carefully next time.

Carin bit the end of her quill as she formulated the answer in her mind. "Edwin Hubble was an American astronomer. He was the one who showed people that there are other galaxies except our own through the MIlky Way, and then there's Hubble's Law that shows how the universe is expanding." She couldn't quite remember the details concerning this law, but she never had been very good or interested in Physics. Oh, well, all she could do was hope that her answer would be enough.

Salander leaned back on his seat, resting his arm on the backrest and cradling his head with his hand. Edwin Hubble?... It sounded vaguely familiar, where'd he heard of that before? Hubble.... Hubble.... Oh yeah!... "He's the dude who owns that space telescope... errr or maybe he went up to space with his telescope? Anyway theres a telescope with his name on it. He also seems to be having trouble seeing the galaxies properly or something so them Astronauts have to keep coming up to space and giving him new glasses. Or maybe just getting his eyes fixed or something like that." Eh history. This was like 100 years ago or something. Salander was just there for the stargazing. In the middle of the afternoon.

Lexi raised her hand and said, "He is the man that invented the famed Hubble telescope that is one of the most powerful telescopes in the world." She was sure that was right.... it might be THE most powerful but she was not sure... Meh. It was worth a shot to try though, Heh.