Random Phylosophy-physics

Foxchild · Postby **Foxchild** » Mon Oct 20, 2003 7:49 pm

Me and my friend were in a fast food place, getting food before class, talking about Halloween. We started talking about ghost(fairly relavent), and from there where said spectors may have come from. Eventually we wound up talking about the possibility of multiple dimmentions. He brought up the idea of the fact that it's mathematically possible to show the possibility of 17 real* dimmensions. (firstly, i'd like to point out that math prooves the possibilty, not a fact! secondly, i have not seen this math, but this friend is fairly well versed in knowledge that doesn't seem to pertain to anything). In any case, he pointed out that we can freely traverse through 3 dimmensions, lenght, width, and hight, and 4th we pass through even when we don't want to, time. He asked the rhetorical question "Well, what if something could only freely move between 2 dimensions, any of the two we travel through, willingly or not. He then said that it really didn't seem possible for something to only exist in 2 dimensions, trying to pull the socratic method on me, and then asked how many dimmensions a shadow had. Well, i took a moment to think, to see if I could find a flaw in that logic, and I could not. A shadow by it's nature only has 2 dimensions. Next he asked what i thought would happen if something were to exist in 1 of the dimensions we pass through daily, but not the other 3. I then suggested the idea of spectors(i was mostley eating at this point, only responding when i had to. We'd be late for class, otherwise, and I had not eaten since that morning), which seemed to fall directly in line with what he wanted me to say (I had not seen the socratic method used so well by any other person, now that I think about it.). I was kinda wondering what everyone here may think of this. Its a little out of this world, but since its getting close to All Hallows Eve, the idea of ghostly sights seems fitting, and this seems like it may be a fair explanation. What are your thoughts on it. (actually, i don't know if this will get any replies, but it was worth a shot!) <img src='http://definecynical.mancubus.net/forum ... /laugh.gif' border='0' style='vertical-align:middle' alt='laugh.gif' />

erikbarrett · Postby **erikbarrett** » Mon Oct 20, 2003 8:25 pm

Ok, I'll take a shot at it. In my understanding, a dimension of reality is just a definition. The fact that there are 3, 4, or 17 dimensions simply states that there are 3, 4, or 17 different "ways" of looking at things in reality... ..ok, that was a bad explanation. Perhaps I don't understand the question. Can you help out? As for the rest, a shadow doesn't exist in two dimensions. It exists in four (or however many) just like you and me. Shadows lying on the corner between a floor and a wall are in three dimensions, and the fact that shadows aren't permanently in one place shows that they are effected by time. Simply because something is flat doesn't mean it's only 2D, or limited by two dimensions.

Foxchild · Postby **Foxchild** » Mon Oct 20, 2003 8:47 pm

Hm... well, the definition of dimension i guess can be kinda vague. I went and found the dictionary definition, so here it is:  <table border='0' align='center' width='95%' ><tr><td class='quotetop'>Quote: </td></tr><tr><td class='quotebody'> dimension: NOUN: 1. A measure of spatial extent, especially width, height, or length. OTHER FORMS: dimensional, dimensionality (-sh-nl-t) , dimensionally, dimensionless</td></tr></table>  Not neccissarily much help... but i think i understand it. A dimension is an area in which we move. We obviousely can percieve distance forward and back, up and down, and left and right, and to an extent, past and future. These each only have two directions, <-- and -->, as in one direction, or the exact opposite(i didn't want to say forewards and backwards because of the first mentioned perception). Beyond this, i have trouble thinking of anything else that could be described that way, because we as people have the large dilema of a limited view of the world. As for the shadow and how many dimentions that exists in... you bring up a very good point, one that is making me think a lot (and therefore is very good). My only response at the moment is that a shadow, just as a shadow has no depth, eliminating one dimention. A shadow is affected by things in other dimentions, such as hight- like a wall on which a shadow transfers from to the floor. and I don't know if a shadow itself is affected by time, or just by objects that ARE affected by time. Maybe someone else can help shed some light on this... IS THERE A QUANTUM PHYSISIST IN THE HOUSE?!?!

Tavis · Postby **Tavis** » Mon Oct 20, 2003 9:38 pm

I'm not a quantum physicist, but I do read Discover and Scientific American when I can. While mathemeticians have demonstrated the possibility of extra dimensions, physicists have verified that if they do exist, they are very tiny. The experiments involved measure the effects of gravity and other forces in distances less than a millimeter. I remember something about a 2D chart in one of those magazines saying whether life can exist in any number of dimensions (spatial as well as temporal). Ugh.. too much thinking.. <a href='http://www.ozyandmillie.net/2001/om20010905.html' target='_blank'>rutabegas are cool!</a> *muttering* Stupid spontaneous Monday pop quizzes asking for pseudocode algorithms from someone whom habitually complicates the question and was half asleep when told to pull out a sheet of paper...

Sabre · Postby **Sabre** » Mon Oct 20, 2003 11:00 pm

<table border='0' align='center' width='95%' ><tr><td class='quotetop'>Quote: </td></tr><tr><td class='quotebody'> IS THERE A QUANTUM PHYSISIST IN THE HOUSE?!?! </td></tr></table>  <img src='http://definecynical.mancubus.net/forum ... s/wink.gif' border='0' style='vertical-align:middle' alt='wink.gif' /> Maybe......

Foxchild · Postby **Foxchild** » Mon Oct 20, 2003 11:06 pm

<table border='0' align='center' width='95%' ><tr><td class='quotetop'>Quote: </td></tr><tr><td class='quotebody'> While mathemeticians have demonstrated the possibility of extra dimensions, physicists have verified that if they do exist, they are very tiny. The experiments involved measure the effects of gravity and other forces in distances less than a millimeter.</td></tr></table>  Less than a millimeter, which means it would have, in essence, a boundry. Interestingly enough, I recently heard a theory that said that our univers was not limitless, that it has boundries. perhaps... in perspective, our universe is contained in one of those tiny dimentions inside something so big, whe can't comprehend it. The more you learn, the less you know. Hmm.

norsenerd · Postby **norsenerd** » Tue Oct 21, 2003 1:15 am

I am a mathematics and physics major who is talking undergraduate senior level classes who independently reeds up on cosmology so I'm probably going to be the closest thing to a quantum physicist that you are going to get. One problem is that the correct definition of dimension has not yet been stated. This is a term from mathematics and cannot be found (correctly) in a language dictionary. The same is true for any other technical term in any field. The Concise Oxford Dictionary of Mathematics does not state the definition probably because it's different depending on what field of study you're in. All of them, though, would be statements of how to describe space. (You can skip this next paragraph if you want. Its mostly technical) The first real definition learned of dimension is from linear algebra (which is a sophomore/junior level course in college). First thing to define is a field. This is a complicated definition but a field is a set of numbers that behave like the real numbers (I will add a topic where I'll put in depth definitions). A vector space is a set of vectors where each vector has addition and scalar multiplication. I can describe the space that humans naturally perceive as a real four dimensional vector space. Once I choose a basis (four vectors) and an origin a can put three special dimensions and one time dimension on each one. A basis is a set of vectors that when multiplied by scalars (a number) and added together gives you the entire vector space and none of the three can be manipulated in a similar fashion from the others. A finite dimensional vector space has dimension equaling to the number of basis vectors. (The vectors arent set. Nearly any four will do.) Thats probably more math than you wanted but I will try and explain it here. A dimension is a way of describing space. I define a particular (the x direction) dimension by saying the positive direction is that way. I then assign numbers to any point in space for each dimension and you get an unique point in space. In that sense a dimension is a direction. The dimension of an object and of a space are different things but both are basically what is the minimum number of directions I can have here? According to human perception all space can be described with four dimensions (three spatial and one time) and no less. Humans, however, are three dimensional objects. You can describe every point on yourself using only three dimensions. Sure you move and change in the fourth but you have no time depth. Shadows are two dimensional objects. They exist in four dimensions but you can describe every point using only two directions. Shadows sometime bend but the directions bend with them. Currently physicists believe that the most fundamental particles (whatever they may be) are dimensionless point particles. From what we can tell it sure looks like quarks and electrons have no dimensions and only exist at a point. I'm not sure the exact number but we can cap the size of an electron to something like 10^-28 meters (thats less then a third the size of a hydrogen nucleolus). I'm probably accurate to within +/- 10^-20 meters). It is very easy to show that seventeen dimensions is possible. Define a seventeen dimensional system. I'll define a seven dimensional system: the dimensions are as follows: 3 spatial, 1 time, red value, green value, blue value. This system (actually more complicated versions) are used allot in computer animations. Define a function that takes any point in space and time your in and assign it a color (possibly clear). There's seven dimensions for you. Typically you have however dimensions you have variables. You can also have infinite dimensions. Take the real numbers as a vector space over rationales. That vector space is an infinite dimensional vector space (I sadly do not yet know the definition of such a thing). This is an abstract example and I don't know of any not abstract things with infinite dimensions. The economy sure has a home of a lot (some of them only have two different values for their dimension). Dimensions don't have to be integers or infinity either. Fractal space is described by fractional dimensions (I have no idea how but I think thats drum cool). The question is how many definitions describe reality. On really large scales it still looks like for does it (and our familiar four too.). The interesting thing is that on large scales space is non-Euclidian (e.g. the sum of the angles in a triangle dose not necessarily add up to 180 degrees, two straight lines can possibly intersect at more then one point. But there are questions like is how curved is space. We know that space is very nearly flat (abs(1-omega_r,m)=<2x10^-4) and even flatter back in time (very early on abs(1-omega_P)=<1x10^-60) (2x10^-60<<2x10^-4). But if it is at all curved, we don't know if it is positively of negatively curved. Positive curvature is like that of the surface of a ball while negative curvature is the opposite (NOT the inside of a ball, that's still positive) like a saddle at the very center and nearby. Interestingly enough it is imposable to have a surface with constant negative curvature in Euclidian space that has no boundary. On really small scales dimension is not what you think it is. First on small enough scales there is no difference between time and space. The two behave the same. There are other examples of how our standard views break down (one if them involves strange wrap around when space is partitioned but since I don't know much here I will leave it alone). There is a quantum theory called Superstring theory that describes reality very well mathematically by adding more and more dimensions to describe the physical world. It stated with describing reality with seven dimension but as the theory was broken down by phenomenon not previously observed to grew and has something like 23 dimensions today. But it is defiantly a possibility that all of reality might be described using 17 dimensions. We really have no clue at this point (this is where all the superstring theorists throw their white board erasers at me for saying that). Also FoxChild brought up the point about the universe having "limits". I'm not sure what limits means but I will address it here. One of the most fundamental rules of cosmology is the cosmological principal: there are no special points in our universe. This means that the universe is isotropic (the same in every direction) and homogeneous (the same at every point). These are different concepts and should not get confused and NEITHER ONE IMPLIES THE OTHER. This is obviously not true from what we see. Gravity pulls you downwards not upwards or sideways and I can move my hand through the air with no problem but when I try and move it through my monitor, it hurts. But on scales of 200 mega parsecs (a parsec is the distance where 1 AU (mean distance from the earth to the sun) is 1 arc minute of the great circle so 1 pc = 2160 AU = 3.1 x 10^16 m, 200 Mpc=6.2x10^24 m) the universe does appear to be very nearly isotropic and homogeneous at every point (there are still inconsequential fluxuations). Thus if the universe had a boundary that would violate this principal for points near the boundary because they would be special (i.e. the 200 Mpc window would be different then the others). To end with I would like to point out that things arent always as they seem. Hopefully if you reed though my explanation then you will agree with me that the earth is three dimensional. But to me where Im sitting looking out I can't see it curve. It looks like the earth is flat, like it's two dimensional. Locally at any point on a sphere the sphere is two dimensional but globally the sphere is three.

LotharBot · Postby **LotharBot** » Tue Oct 21, 2003 6:11 am

A few things to note: 1) I remember recently hearing that the universe can be reasonably described large-scale as a manifold in four dimensions (x, y, z, and t) but that most small-scale descriptions require ten dimensions. You *can* use more to describe it, but only 10 are strictly necessary for a complete description (all of the others can be viewed as functions of the first 10, through some physical laws.) 2) While the earth is 3-dimensional, your observation that it's "locally 2D" is not technically correct. It's locally 3D -- grab a shovel and check. However, its surface is locally 2D and globally 3D, which is probably what you intended to convey. It's essentially a 2D manifold in 3space. Whether space is a 4D manifold embedded in higher dimensions, or whether it's a 4D manifold in four dimensions, nobody really knows. 3) A shadow is, strictly speaking, a projection of a 3D shape onto a set of 2D surfaces (perhaps arbitrarily ugly) -- which, I believe, forces it to be a 2D manifold, though not necessarily a smooth manifold. 4) I'm not sure about the universe being either isotropic or homogeneous -- if these are scientific observations, all they really show is that the *observed* universe is both, not that the rest of the universe necessarily is. If we haven't found the boundary yet, our observations may not show it to us <img src='http://definecynical.mancubus.net/forum ... s/wink.gif' border='0' style='vertical-align:middle' alt='wink.gif' /> And, of course, studying some boundary layer theory will quickly point out to you how easy it is to miss such things...

simon · Postby **simon** » Tue Oct 21, 2003 12:12 pm

Wow norsenerd... I'll need to print that out and read it sometime. :P

norsenerd · Postby **norsenerd** » Tue Oct 21, 2003 2:29 pm

Lotharbot brigns up several good points. Points 1-3 briing some more rigour to my discussion as well as some insight to the nature of the universe on small scales. Point 4 also brings up a good point about cosmology. Throught most of history people have been claiming to know the center of the universe. First it was eart, then the sun, then the center of our galaxy. These things were not ingorant at the time (well, most of the time) because the matched our observation. According to curent observation at distances of over 200 Mpc the universe dose not apper to have variation. We can measure allot more of the universe so this is reasonalbly good evedince that it dosn't variate that much. Granted we can only see a small portion of our universe (posably a infatesamly small fraction of thw whole). But we can look back in time. The distance we can se is caled our horizon distance. Outside this area whatever hapened there had no time to efect us even if information was caried at the speed of light (we have yet to find anything that can move faster then the speed of light, also nothing going slower or at the speed of light can accelerate to go quicker). Looking back until the early reaces of the universe through the cosmic microwave backround the universe also looks homogenous and isotropic. The shape of what we can see back this far looks like a sherical shell around us. The horizon distance at that point is 2 degrese. This means that we can see 16200 times what we can see today and the universe also looks isotropic and homoenious with slight variations (like today). Curent observation points to the universe being isotropic and homegenious. That stated at one point in time the curent observations pointed to the earth being the center of our universe. The cosmological princaple has something of a belief element atached to it too. While there is evedinmce suporting it it is also excepted because people don't want to say this is the point that is diferent from evrything else. But this is an aside because the universe certantly does look to be isotropic and homogenious. (It's one of the 5 most fundamental observations of cosmology). All that said I think that evrything that we believe curently will be shown to be wrong. Look at waht we believed 2000 or 3000 yoears ago and compare it to what we believe today. Then use the same comparasion to look at what we will elieve 2000 or 3000 years ahead of us. It's probably going to be different. I can imagine aa conversation "Man, I can't believe that we used to believe in evolotion." So, we cirtantly do not know. Also as for ten dimensions needed to discribe quantum space. I know that Superstring theory uses more then 10. That's all I'm saying there. (I'm not a big fan of Superstring theory)

Foxchild · Postby **Foxchild** » Tue Oct 21, 2003 5:25 pm

I'd just like to point out to anyone who'se reading this, but norsenerd wrote 5 pages of 12 font, double spaced worth of material in just his first explanation!

LotharBot · Postby **LotharBot** » Wed Oct 22, 2003 6:18 am

With respect to the point that everything we believe now, in 3000 years we will probably think was foolish... read through <a href='http://www.angelfire.com/ego/thomashanc ... wrong.html' target='_blank'>The Relativity of Wrong</a> by Isaac Asimov. He makes some fairly good points on the subject.

erikbarrett · Postby **erikbarrett** » Wed Oct 22, 2003 5:06 pm

Wow. This is one of the reasons I don't philosophise much in physics: I know there's a lot I don't know. Thanks for the time, Norsenerd. Yes, I did catch most of that. I'm glad someone explained it better than myself. Two days of thinking gives me a clearer idea of what I was trying to say then my first post.

norsenerd · Postby **norsenerd** » Wed Oct 22, 2003 5:58 pm

Another interesting thing to ponder was that by 1975 both the general and special theories of relativity were proved wrong. As far as I know there is not a generally agreed upon mechanics to replace relativity and relativity remains a good approximation (so does Newtonian for everyday life) but still we know that relativity is in fact wrong. Not only that but it was disproved 70 years after its inception.

ravage · Postby **ravage** » Wed Oct 22, 2003 9:36 pm

I'm suprised no one has mentioned Philotes, Inspace, and Outspace. <img src='http://definecynical.mancubus.net/forum ... tongue.gif' border='0' style='vertical-align:middle' alt='tongue.gif' />

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