Wednesday, December 30, 2009

Randall's maze 6

This brings me to a very interesting point (it’s totally a tangent from Randall’s book, but oh well). It has to do with God! So God’s supposed to be omnipresent, right? Everywhere at once? Well that would include extra dimensions. And if he created the universe then he must have created those extra dimension. He created time. This means he was not subject to it in the beginning. And he must exist outside of it! And like I was saying before we are 4-D (at least) creatures. So he must see us that way. So when God looks down at a person, say Einstein, he sees him as a holistic 4-D creature and not him as an old man (the way most of us are used to seeing him). It also means that whole thing about him knowing the future and us still being able to change it doesn’t even apply. When you think about it this way a whole host of interesting consequence pop out at us. I would really like to hear what you guys think about such a weird concept so send me a line!

Monday, December 28, 2009

Randall's maze 5

Now for another term. You know how I said that physicist and mathematicians put numbers onto our axes? Well this may seem like not that bit of a deal when we are just moving a string around a table, but when theorist make up new math these numbers become very very important, they even get their own name. They are called the metric of a system. If you’ve ever dabbled in relativity you will hear this work a lot, usually preceded by someone’s name. All they means is a specific system of units and measurements that goes along with the coordinate system they are talking about.

Now if I could I would like to take a moment to talk about time. Einstein declared it to be one more dimension and stated that we now had 4 dimensions. How does that fit into all of this? Well it is an extra dimension by not an extra spatial dimension (you know I just learned how to spell spatial…what a weird spelling). But how to picture this? Well…just like we normally would. Imagine yourself as a baby, a 5 year old, a 15 year old, a 20 year old and so forth to your current age. If you string these images together you get your 4-D projection. We are in all honesty 4-D creatures. We grow and change with time.

Sunday, December 27, 2009

Randall's maze 4

All right now that you know what a vector is we can talk more about dimensions. In the exercise we did yesterday you were using a 3 dimensional coordinate system. There were 3 axes each corresponding to a different dimension. And we needed 3 different numbers, an x component, a y component and a z component, to specify exactly where your vector end was located. If you only had one dimension you would only need one component to tell where your vector end was located. And the same holds for five dimensions. You may not be able to draw a graph like that but you still only need 5 numbers or components to specify a location in 5-D space. I've included a picture of some objects in 2, 3 and 4 dimensions. String theory and now M-theory suggest 10 and 11 dimensions, respectively. Why so many?

Saturday, December 26, 2009

Randall's maze 3

Hello!!! And Merry Christmas! I hope it was a good day for all. And now back to physics. So in order to more fully understand what Randall means by ‘dimensions’ we need to understand the concept of vectors. This took me two years to fully understand! It’s a weird concept for those who aren’t used to it, so take your time and think about it… So what is a vector? A vector is just a straight line. But when we say vector with regard to dimensions we’re talking about a straight line anchored at one point. (no one on the internet seems to have done this so I will go ahead and do it!) Here’s an exercise that should be helpful. Get a piece of string (or something like it). Now we are going to set up a 3 dimensional coordinate system. All you have to do is declare and origin (or zero point like in the picture), it could be the corner of a table or a book or anything. Next you need to declare an axis. The normal axis in math and physics are: left right or x, back and forth or y, and up and down or z. Next hold one end of the string against your origin. That is the anchor for your vector. Now pull the string taut in any direction. And there you have a vector. You can move the one end but not the one connected to the origin. Ok now pick a vector position. Take your finger and put it up to the end of your vector. Now drop it straight now onto the table. This is your vectors ‘projection’ onto the ‘x-y’ plain. Now if you run your finger straight over to one of you sides or axis you have that axis, say the x axis, ‘component’. The only thing that physicist and mathematicians to is put numbers on them. I hope this walk through was helpful. If it wasn’t let me know and I can change it.

Monday, December 21, 2009

Randall's maze 2

So why would be even bring such a crazy ideal up? We can only see 3 dimensions…why would there be more? Well why not? Why couldn’t there be more than 3 dimensions? Perhaps that could solve some of the weird problems we have in physics. And according to Randall, they do. There is one that I find fascinating that has to do with gravity. Have you ever thought about how weak gravity is? It’s really really weak. Even though you have the entire pull of the whole earth on you, you are still able to jump off the earth (it’s actually the electromagnetic force that allows you to do this). So in comparison to all the other forces gravity is really weak. Why is this? Randall and some of her colleagues say that it’s because the gravity is shared with the other dimensions. Fore some reason or another it’s stronger in those other dimensions than in ours and that’s why it seems so weak. Now, of course, that’s not all there is to her idea. There is a lot of super complicated math that I haven’t even looked into to go along with that general idea, but the point it extra dimensions are defiantly worth taking a look at.

Sunday, December 20, 2009

Randall's maze 1

A couple of corrections. First Randall is spelled with 2 l’s. Second she hasn’t won the nobel prize…yet. So far I’ve gotten through the introduction and it looks like a fascinating book. It’s all about extra dimensions. So we are all familiar with our normal three dimensions, up-down, left-right and forward-backward. I used to have trouble explaining this concept because people can move in any combination of these 3 ways but most of that difficulty has been cleared up by (of all things) video games. When the first video games came out they were 2-dimensional you could only more forward-backward and up-down. But now they have those really advanced video games with toggles and if you push the toggle just forward you only go forward or side to side or you jump up and down (or in those flying video games up and down…those games are so hard to get the hang of). So basically what the book is about is the idea of there being more than just those three space dimensions.

Friday, December 18, 2009

fyi

Just an fyi (I just figured out what that meant!), I’m on vacation so my posting might be rather erratic. But I think I’ve found something to do while all of my library books are in hock…well I guess they’re not really mine…but…whatever. My friend lent me this book called “Warped passages” by Lisa Randal. I think she won the Nobel prize. It’s about higher dimensions and stuff, M theory and such.

Thursday, December 17, 2009

Pop physics

So a breakdown of the graph: The little blueish slice there is the stuff we can see. All the stars and galaxies and everything that emits light is accounted for in that slice. And it’s a pretty small slice. The orange slice is the interstellar gas. This is the stuff that the stars form from. It’s mostly hydrogen and helium, and some carbon and bits of heavier elements. It floats around the universe and sometimes collapses to form stars (I’ve included a picture of some gas backlit by some stars). And the speckley grey stuff is obviously dark matter. It’s the stuff that contributes to gravity to hold the universe in the precarious balance that it sits in. And the rest is dark energy. And there sure it a lot of it. I’ve always found this graph amazing. All the stuff we’ve ever been impressed with or looked at or awed at is only the tiniest fraction of all the ‘stuff’ in the universe. That’s just nuts!

Wednesday, December 16, 2009

Pop physics

Ok so here we are in the 1970’s and we are very confused. There is this extra mass around the galaxy and we don’t know where it’s coming from but…it’s there! It must be there. It was certainly a time when many a physicist was questioning their sanity. But what has happened after that…? I have no idea, and I don’t have the time to figure that out. So, let’s skip to the stuff I do know. What has been established since…I don’t know, the 1990’s maybe….is the amount of ‘stuff’ in the universe. I’ve included a graph of all the ‘stuff’ in the universe as we know it today. So what we did is count all the stars and galaxies and gas that we could see and then compared it to the amount of gravity we could see and saw there was a lot missing. And by the looks of things we are missing a lot of energy in addition to the mass we were missing (remember that ‘stuff’ includes both mass and energy, E=mc^2). And so when we put all the ‘stuff’ we need back in we get the graph I’ve included. I’ll talk more about the graph tomorrow.

Tuesday, December 15, 2009

Pop physics

Ok so more dark matter. Last time I told you about the guy who first came up with the idea, Fritz Zwicky. But like I said he was kinda crazy so no one took him seriously. It took experimental evidence to get the idea under way again. In the 1970’s this lady named Vera Rubin looked at the rotational velocity of stars in different places throughout the galaxy and found the graph that I’ve included. So basically she looked at the speed of a star near the center and then a star further out in the galaxy and what we expect to see is a steady drop in speed as we go further out because the gravity is weaker out there. BUT what she found was that the stars near the edge of the galaxy go just as fast as the stars near the center. But this doesn’t make any sense with the amount of gravity we thought there was. So what is the explanation? There must be some more gravity that we can’t see. There must be dark matter!!!!

Monday, December 14, 2009

GOD! ?



any ideas on what you want me to write about next??? anyway...here's some pic's till i figure that out...

Sunday, December 13, 2009

confession

Ok so I have a small confession to make: I don’t actually own the book out of which I’ve been writing out of. It’s a library book. And it needs to be returned. So I think we can put the whole “by the book” thing on hold until a certain arbitrary amount of time (three weeks or something) has passed and the library lets me check it out again. So until then I have to figure out something else to talk about. So any suggestion? More pop physics? More philosophy stuff? Let me know…

Saturday, December 12, 2009

By the Book 12

Ok so here’s the interesting part (I’m feeling a little better by the way, I went to the doctor and he gave me pink mold in a bottle, I can’t get over the whole Penicillin thing), so ya know the whole matter-antimatter thing? Well that applies here. When temperatures started to drop at the end of the hadron era annihilation happened more frequently than creation and all the hadrons started to disappear. But we still have them? So why do we have them? Well according to Harrison its because there were slightly more matters than antimatters to begin with. He says the ratio between the fraction that survived (the difference between the matters and antimatters) and the total number that there was at one point is about 10^-9. In other words only about 1 in a billon of the original matters survived. And yet this amount of matters is what makes up the whole universe as we see it today. And when all the rest of the matters annihilated with the antimatters they created a whole bunch of energy. And this energy is what we see today as the photon and neutrino backgrounds. Our universe has done a pretty amazing turnaround since its beginnings no?

I guess matter and antimatter shouldn’t be plural.

Friday, December 11, 2009

no post tonight...i've got this cold...and a fever...is it still considered a cold if you have a fever...anyway...sorry

Thursday, December 10, 2009

By the Book 11

Ok maybe this won’t take as long as I thought it would. What is a hadron? A hadron is a particle made of quarks. There are 2 different kinds of hadrons, the mesons and the baryons. Mesons are made of a quark and an anti-quark, (wait…I talked about this before didn’t I?) and baryons are made of 3 quarks. There are also anti-baryons, made up of 3 anti-quarks. I’ve attacked a table of a large number of the hadrons (and the quarks). There are two of importance to our everyday lives, the proton and the neutron. They are each baryons made of 3 quarks and…obviously they are our everyday nucleons at the center of all of our atoms.

Ok, so back to the hadron era. Just like the lepton and radiation eras the reason it’s called the hardron era is because it is dominated by hadrons. Hadrons are very heavy particles, at least compared to electrons or massless photons. So they take more energy to make (remember E=mc^2. You see it is useful for more than just the atomic bomb), and consequently the early universe can only produce them at very high temperatures. And as we go back and back temperatures get higher and higher and consequently we have a hadron era, but there are some subtleties…that I will talk about another day.

Wednesday, December 9, 2009

Pop physics

Ok so I thought that for the days when I don’t want to do read out of the book cause it does take a substantial about of time to figure that stuff out, I think I’ll try to explain some of the topics in pop physics that I know a thing or two about. First up:

Dark matter

The mysterious substance that seems to have appeared out of nowhere. It is very easy to be skeptical about such a (to borrow my 14 year old neighbor’s term) sketchy substance. But it’s not all smoke and mirrors. (look! I made an awesome introduction!) So here’s what I know. Dark matter was first proposed by Fritz Zwicky in 1933, but no one took him seriously (here’s his bio and here’s his facebook). So that’s the intro to Dark matter and when I feel lest like I’m going to keel over I’ll write more.

Tuesday, December 8, 2009

By the Book 10

And on we go…ever further back into time! We find ourselves starting at the beginning of the lepton era at a universal age of 100 microseconds and moving backwards. At this point things get shaky! Up until now all the stuff we’ve talked about in the by the book segments has been part of the standard model of the early universe. But now is when we get to the strange speculations that not everyone agrees on.

So get this: at this point in the universe’s history the temperature was 1 trillion Kelvin, and the density is 10^14 grans per cubic centimeter. That’s equivalent to 100 million tons per thimbleful! That nuts! The next era is the hadron era. But I would like to take a step aside from the book and take a moment to discuss some to the physic background we need in order to understand the hadron era to its fullest.

Monday, December 7, 2009

By the Book 9

So we’ve got a bunch of these neutrinos floating around in space…ya know free floating, just like the CMB, except not light. And we can calculate their temperature and stuff so we should see a background of them … if, that is, we could see neutrinos. But they don’t have any charge and barely have any mass so they are really really hard to see, but…we’re working on that. And eventually I think we will be able to see them better. When that happens something else that’s very cool will happen. Remember how I said we couldn’t see any further back in time because there wasn’t any light to look at before the end of the plasma period. But if we were able to see the neutrinos then we would have a small, strange window into the first second of the universe. This is monumental. We would be looking much further than we ever have before! And who knows what we would find!

Sunday, December 6, 2009

By the Book 8

There are 6 different kinds, electron neutrinos, tauon neutrinos, and muon neutrinos, electron anti-neutrinos, tauon anti-neutrinos, and muon anti-neutrinos. But here’s the thing, neutrinos don’t really annihilate each other…I’m not sure why they don’t but they don’t. Also, each kind of particle only interacts with it’s respective leptons, tauon neutrinos and anti-neutrinos only interact with tauons and so forth so during the lepton era when the various leptons started annihilating the neutrinos had nothing left to interact with. So…what did you do? Well as far as I can tell they just spent the rest of their existence floating around in empty space doing nothing at all…just floating. Interesting yes?

Saturday, December 5, 2009

By the Book 7

I should note that muon pair production only happens at the very beginning of the lepton era because they are really heavy and (if we invoke E=mc^2 again) it takes more energy to create some heavy muons compared to some really light electrons. Also the tauons are even heavier then muons so their production took place even earlier.

As the lepton era draws to a close the universe is expanding and the temperature is dropping. Tauon pair annihilation starts happening more frequently than pair production and soon almost all the tauons disappear. Then the same thing happens with muons later and then the same thing happens with electrons a little latter (they don’t vanish completely, but before there were crazy ridiculous amounts of them…now there are just a reasonable amount of them).

Ok now to talk about neutrinos! Neutrinos are tiny little particles that have barely any mass and travel at near the speeds of light. They don’t have any electrical charge so they tend not to interact with anything. They were predicted by theory, but it took us forever to find them. There’s a cool documentary on them. We’ll talk more about them tomorrow.

Friday, December 4, 2009

GOD! ?



here's some more. let me know what you think.

Thursday, December 3, 2009

By the Book 6

Ok so if you look graph the density graph you will see that before the radiation era there comes the lepton era! You remember what leptons are, don’t you? They are the things that aren’t made of quarks, like electrons and tauons. This era begins when the universe is 100 microseconds old, that is .0001 seconds old. And the temperature was a trillion Kelvin or 100,000,000,000 Kelvin. Oh, and it was really really dense! Apparently this is when electron pairs where created. I might have talked about this before. So this is when two electrons (an electron and a positron) where spontaneously created from some energy (usually in the form of a photon) and then they get annihilated when they run back into each other. And it wasn’t just electrons it was tauons and muons and their neutrinos and all various forms of leptons. But this was happening all around so quickly and there was so much energy to create them with so the universe was a frothy mix of energy and leptons.

Wednesday, December 2, 2009

By the Book 5

Ok...so you know you are old when you write out an entire post and forgot to post it, so here's yesterday's post.

Before this ‘decoupling epoch’ or plasma period comes the ‘epoch of equal densities’ (I’ll have to make up my own spiffy name). So I think the all the ‘epoch of equal densities’ denotes is when the shift from radiation dominance to matter dominance occurred…yeah I think that’s it…but I could be wrong.

Before this was…obviously the radiation dominance era. This ere began when the universe was only a second old and lasted for about 100,000 years. Harrison takes a moment to talk about what it must have been like to be there in person, and I had never thought about that before. You would be trapped in a super hot fog of light. You would be surrounded by extremely intense white light (among all the other wave lengths). That would be pretty cool.

Shortly after the radiation era begins free protons and neutrons clump together to form helium nuclei. There were already a lot of hydrogen nuclei (protons) and a bunch of free neutrons and when the temperature got just right…they came together like the detonation of a giant hydrogen bomb all over the universe! But can you believe it… the temperature of the universe was already so high that the fusion of all that hydrogen into helium didn’t raise that temperature that much. Crazy stuff.