Perspective Definition and 207 Threads

My real passion lies in nuclear medicine, which of course, contains physics albeit NOT straight physics in the sense of physics COURSES on offer - the degree offers ONE straight physics course in first year. The problem is, I was a high school drop out, have never learned physics, and only...

I still can't quite grasp the scale and size of our universe. Can you guys give the basic facts? Size of universe? Number of stars? Number of galaxies? Size of our own planet/sun in comparison to others in existence? Thanks very much! :approve:

Hi friends, I was wondering about the following - in GR texts we always see these penrose diagrams and some line representing the horizon and all these timelike , spacelike curves and all that ... but the picture that I have of GR is just that of a smooth 4 manifold endowed with a metric . Can...

So, I assume to look at multiplication as addition; how should I look at division?

Trying to understand small increments of light. From a particle perspective, a photon is the smallest increment, dependent on frequency as E=hf. From Maxwell's wave perspective, light propagates as a result of the energy passing between the E field and the B field. The rate at which this...

AN ENGINEERING PERSPECTIVE ON CHRISTMAS There are approximately two billion children (persons under 18) in the world. However, since Santa does not visit children of Muslim, Hindu, Jewish or Buddhist (except maybe in Japan) religions, this reduces the workload for Christmas night to 15% of...

I am pursuing electrical engineering and I am currently in my 3rd semester. I have field theory or Engineering electromagnetics as a subject. It seems very interesting but I am not able to figure how to approach the subject to enjoy it. Hence I need to change my perspective from just...

Hello All, I like to think that I have a decent background in physics and related material, but I confuse myself quite easily on, well, everything. I guess I think about it too much, really. So feel free to give complex answers and I will do my best to follow along accordingly. Anyways, here...

is it a good thing to understand physics by intuition ? or is it a bad thing ? lots of people told me that sometimes i have to take things as they are , but i really can't do that . i mean , yea i understand mathematical relations , but i don't really understand anything just by its math ...

This paper makes some interesting points: A Dynamic Dark Information Energy Consistent with Planck Data, http://arxiv.org/abs/1308.2382.

I'm working on an animated short, and want to find ways to quickly calculate the positions of objects on the drawing plane from their changing positions in the imaginary 3D space. The thing that has me slightly stuck at the moment is figuring out how to creata a 'moving forward' loop in...

I'm having trouble understanding the arguments in http://arxiv.org/abs/hep-th/9510209 They propose that M-theory on the orbifold R^9 \times S^1 \times S^1 / Z_2(1) yields Type I' on R^9 \times S^1, wheras M-theory on R^9 \times S^1 / Z_2 \times S^1(2) is E_8 \times E_8 on R^9 \times S^1. What...

Hello, This might be a bit of a stupid question, but if there were a universe of 4 spatial dimensions and photons behaved in the same way as in ours, would a 4D "hyper-alien" be able to see 4D perspective with only 2 hypershpherical eyes, or would it require more? In case my question isn't...

Imagine looking at a set of x-y-z axes, from directly along the z-axis. Say in this image, the road is the line z=0. Why is it, that only lines on or parallel to the z-axis get skewed? All the surfaces that are in or parallel to the x-y plane remain undistorted, and their angles are at 90...

First, an unnecessary short introduction of why I'm asking this question in the first place. Due to some doubts about a certain plot device in a science-fiction novel, I'm trying to figure out how long it would take to accelerate someone to, say, 50% of the speed of light under constant...

So sound is a mechanical wave usually a propagation of atmospheric pressure in a medium in the classical interpretation.I`m curious what happens in the quantum realm ? Also if this pressure force is giving kinetic energy to those atoms,but due to friction is also generates heat energy,and with...

Some questions have been haunting me about this experiment for some time. I'm mainly interested in what we observe from the perspective of the projection screen. First let's imagine that there is only one slit, and we are observing from the projection screen looking back at the slit with the...

I was watching Lincoln last night, and at a part were the idea of women voting was laughed at by the legislators. My mom's comment was along the lines of "Oh right, women weren't smart enough to vote back then." or something similar (and a sarcastic tone of course). My retort was that around...

I am trying to gain some understanding of what SR 'tells us' about the universe. The following statements are made from the imaginary perspective that light would have. Are they correct? 1. A light wave observes no time passing for any matter. 2. The light wave is absorbed or is at the...

This might not be original, but I wanted to throw it out there. The Drake equation is typically used in the sense of the question, "Is there life in the universe, and what is the probability that WE can detect/find/communicate with it?" In other words the underlying assumption is that we...

For a mathematician, how is rotation defined in the most general sense? Question arose to me because it occurred to me that an essential property of the rotation matrix is that it preserves lengths. Is this the only mapping (if not please give me a counterexample) that has this property...

Since temperature is no more than vibrating atoms (in Feynman's words), wouldn't that induce a changing electric field, just very slow in some cases? If so, is everything that is not 0 degrees kelvin radiating some kind of EM radiation? Like an ice cube, does it radiate small amounts of radio...

Hello! I am new to the forums! (Love the F=MA and P=MV questions that they ask you when registering!) I need some feedback on an essay that I am writing for the UVa supplement. Would someone be willing to help? The prompt is- If you were given funding for a small engineering project, what...

My understanding of the S&G relativity is that one theory deals with reference frames at speeds near the speed of light while the other deals with reference frames that are approaching the speed of light. There are variances in observation between the two reference frames arising from their...

Ok, I'm applying for fall 2013 PhD programs and one masters (at an institution that funds its MS students!) in astronomy, specifically planetary science. I'm a somewhat nontraditional applicant and need some perspective on my application. I majored in English and minored in Astrophysics, but...

I am under the impression that the Earth orbiting the sun is really a matter of perspective and we can actually take a perspective in which the Earth is stationary and the sun and everything else move in relation to it. And we can take any perspective we want but we just have to use fictional...

The question is on page 10 of this link http://www.educationaldesigner.org/ed/volume1/issue3/article9/pdf/burkhardt_09_fig3.pdf It is the question about the mountain. In particular I would like help with the last part about which mountain appears taller to Simon. Could you please explain how you...

Hi all, Just looking for some advice regarding university (again). Here's the 411 on my situation: I'm just your average mathematics major at a big public university in Canada. I've gone through freshman year with excellent grades and am about to start my second year in the math honors...

I'm making a 3D rotation of a poligon.The problem is when I rotate some points in 2D, it works, but if I use the same function to rotate the same points in a 3D perspective , while rotating the vertices move to the center of the object and remain there. I also wrote the 3D rendering part.At...

I'm struggling with trying to visualize the vector potential as in the identity: B = ∇⨯A For starters, how does A relate to, say, a uniform magnetic field, which is quite easy to visualize. Then, how about the magnetic field around a bar magnet -- where is A? Any help would be appreciated.

I'm doing some 2D pencil diagrams (CUD - computer-unaided design). So I've got a square in perspective (2 point perspective but 1 point perspective is good enough). Now I want to draw an ellipse within it, so that the ellipse is properly tangential to all four midpoints of the square. I have...

Can a model be countable from its own "perspective"? I'm reading about Skolem. And I'm wondering about the result of the paradox: that countability (at least in first-order formulations) is relative. Now, even when we state Skolem's theory -- if a first-order theory has an infinite model then...

Hello fellow phyisics geeks, I am quite happy to finally find a forum in which the topic of physics is commonplace. I have am new here posting, but I have been reading posts here for a while. I do have some questions that I would really appreciate some help with. First a little about myself...

I need some help to answer a question as my physics background, while self taught, still has some holes both from following only specifics and gaps since studying it. The question is below. "is there a reputable function for the effect of time dilation in special relativity or is just...

hey , i want to hear your opinion on good books i could read . I just read "whats life? and mind and matter by Erwin Schröndinger , and I am looking for a book that tries to answer similar questions in a physical or philosophycal way , but from a different perspective, and with some...

Thanks a lot for your time, I assume this is the correct subforum for my question, if not, please excuse my mistake. Is it possible to have a 1-, a 2- and a 3-vanishing-point perspective object in one room? I’d like to know this out of curiosity and for understanding and teaching drawing. More...

Okay, so i have read one or two articles about cancer from a evolutionary perspective. However it still its not clear how cancer cells have a particular advantage in our body ? Is it that cancer cells have increase their survivability by rapidly multiplying - are there any examples of this in...

There are two sides to every issue: one side is right and the other is wrong, but the middle is always evil. -AYN RAND Is she trying to say that being a moderate is bad? What exactly does this quote mean?

http://arxiv.org/abs/1202.3373 A perspective on the landscape problem Lee Smolin (Submitted on 15 Feb 2012) I discuss the historical roots of the landscape problem and propose criteria for its successful resolution. This provides a perspective to evaluate the possibility to solve it in several...

Hello Forum, can anyone explain why a camera, a lens, automatically creates perspective in an image? Is it explainable with ray tracing? thanks fisico30

These damn shows on the Science Channel seem to raise more questions for me than they answer, and maybe I'm understanding this wrong but here we go... If I were an unfortunate soul who fell into a black hole, the show claims that I will not feel a thing as I pass through the event horizon...

[I'm more concerned with how mathematics is taught in university in this topic] I'm a junior Mechanical Engineer and have taken Differential & Integral Calculus, Multivariable Calculus, Differential Equations, and Linear Algebra. Just from these classes and talking with a variety of peers in...

Hi, I have used Mathematica to determine a 3x3 perspective transformation from one 2D image to another. Let's say that Mathematica gave me the following 3x3 matrix: a b c d e f g h 1 Now, moving outside of Mathematica, I'm trying to use that perspective xform it gave me in...

Apparently my last post was seen as 'posting nonsense' so I will try to elaborate more constructively. In it, I asked, "How much of the male domain is the spirit of the explorer, the adventurer, the frontier man?" The reason I ask this question is because I teach disconnected teenagers...

Sorry guys if you have already covered this subject but someone the other day mentioned time wells and different frames of reference etc. and I was wondering: If time slows down the more massive and dense things are then how can that effect the observer's perspective? In other words when we...

Im an undergrad physics student, who has lived and learned in the US all my life, for obvious reasons has taken a lot of math courses in college. A lot of these courses covered quite a few proofs, and a lot of conceptual proof-ish questions (aka not rigorous proofs but still requiring you to...

I didn't know where to post this question, but the general math forum seemed like the best idea. Newton's Laws are invariant with respect to the Galilean transformations. Maxwell's equations are invariant with respect to the Lorentz transformations. My question is, is it necessary...

I completely understand the effects of parallax as well as perspective...intuitively; but I can't seem to explain them to a particularly inquisitive child I'm tutoring. He wants to know, in conceptual terms, why objects in the distance like the moon seem to move in the same direction as you...

I thought about what gaining weight means. Isn't the following (obviously) correct? When you eat X grammes of something you momentarily gain X grammes of weight. The only way to lose weight is to go to the toilet or sweat. However, when you sweat most of the mass is water so this is easily...

Hi! I want to know, the value of perspective in exact number. Like how much is the angular convergence between two points A. Camera ----------------------------------------------------------- Building B. In the above how much would building converge, and what would be the size...