Beginning Definition and 179 Threads

I've been trying to find the latest, best guess, as to how long ago the universe's expansion began to accelerate (post-inflation). I've seen various estimates on websites from 5 billion to 8 billion years ago. Is there any kind of consensus in the community that studies these things as to a...

This is problem 1.16 from Kleppner & Kolenkow's Introduction to Mechanics. I didn't know whether to post it here or pre-university math. A sportscar, Fiasco I, can accelerate uniformly to $120$ mi/h in $30$ s. Its maximum braking rate cannot exceed $0.7g$. WHat is the minimum time required to...

I will be going to college next year and the course is called 'Fundamentals of Physics', it is assumed that the students have never done physics. It is a calculus-based course that covers mechanics, thermal physics and waves. After researching, I have narrowed my options down to two textbooks...

I know this post is in the topology thread of this forum, for group theory, this seemed like the reasonable choice to post it in. I realize group theory is of great importance in physics and I'm trying to eventually understand Emmy Noether's theorem. I'm learning group theory on my own, and...

As far as i understand the current big bang theory, it started as a extremely dense object, finite in size. But we still think (or well it is very accepted to belive) that the universe is infinite. I know inflation should be though as an expansion everywhere at the same time rather than the ball...

find the arc length for the curve $y=sin^{-1}+\sqrt{1-x^2}$ with starting point (0,1). $y'=\frac{1-x}{\sqrt{1-x^2}}$ $\int_{0}^{x} \ \sqrt{1+(\frac{1-x}{\sqrt{1-x^2}})^2},dx$ my answer is $\frac{-2\sqrt{2}*(\sqrt{\frac{1}{x+1}}-1)}{\sqrt{\frac{1}{x+1}}}$ i think my answer is wrong though

Homework Statement Left blank Homework Equations Left blank The Attempt at a Solution Well, I am not familiar with the Latex system on this website, just because I am a newbie and I rarely access to this forum. I have a problem (may be simple for you guys) but I still need a...

ok, I can understand that we can see object billion light-year away because it took light a billion year of traveling to come to us. But where I don't understand is why we can see object at 14 billion light year (or close) away or maybe why can we see light emitted close to the beginning of...

I'd like to start learning at home real analysis. Now, in order to start there was an older book Techniques of mathematical analysis by Tanter which looks good as preparation. I also saw that another user SanjeevGupta studied the same one, and found it good. I'd like to see some comments on...

For one of my classes, our project is to write a script that simulates the game of craps. I have no problem with the actual game, but one of the criteria is that after the player wins or loses, we are supposed to prompt them to quit or play again (this is where I'm stuck). Is there a command...

Some background: I've never been good at math, although I'm finding that it doesn't necessarily mean I'll ever be good at it. However, when I was younger (US grade K-7) I was always an A+ student across the board; I've always loved learning and even though I experienced some turbulence, that has...

Hi, Basically I would like to learn about the beginning of time and I am wondering what literature I should read surrounding this. **For the record; I have a Master's degree from a top university in Astrophysics** Thanks in advance!

Math Topics to Self Study Any recommendations for a 9th grader? I have taken algebra 1 and 2 and am currently taking geometry. I find that math class is sometimes very slow. I understand that some students need extra help, but for me it's a bit slow. So to take initiative, I want to learn...

Hello all, So I graduated last May with a bachelors degree in physics. Since then I've been looking like crazy for a job. Right now I'm in a situation where I would love to do something involving physics, but would also be completely fine with doing Data analysis, or any other field that...

Please be patient with me, and forgive me for my ignorance, but I do think according to logic and take into account the facts established by science. Here is my take on how we come to know that the universe has a beginning. The universe is expanding, so scientists by mathematics infer...

At DARPA Robotics Challenge while robots could solve a numbver of things, they were still slow and clumsy compared to humans, and required some amount of remote control, when they had to face with complex tasks. Of course, it isn't good to send humans into radiation and hazards like that, but...

Hello everybody, I'm doing a little research for an Astrophysics course and I am supposed to talk about some older theories that have been developed to try to explain the beginning of the universe before the big bang theory became widely accepted. Sadly, when I look for them, most of what I...

Hi everyone, new guy here. I am currently writing a short essay on the beginning of the universe. I chose not to put this in the Homework section mainly because it does not fit the template, and I think that it's an interesting discussion. More interesting than a simple homework. My essay...

Hey guys I need some advice: I am a Math/Physics freshman whos pretty much a noob to programming in general; I have some experience with Fortran (taught as part of laboratory) and Python (self taught) but only in the context of elementary numerical methods / scientific computing. I have...

Homework Statement Show f(x)=(x−2)sinxln(x+2) has f'(x)=0 somewhere on [-1,3] The Attempt at a Solution I tried using Rolle's theorem, but f(-1)≠f(3). Then I tried the mean value theorem, but didn't get 0 either.

It makes no mathematical logic to say the universe started with a minute pinhead sized mass that suddenly exploded and start expanding. If this were true, then what entity is the mass expanding into? Humans must accept that the universe is infinite and unbounded... with no beginning and no end...

The title's pretty much self-explanatory. I'm totally new to Physics. I know absolutely nothing about Physics and I've never picked up a physics textbook before. What better way then to come into a Physics Forum! I'm currently in 8th grade and going into 9th grade. I was inspired to start...

I am very new to physics and astronomy, so I don't know much, but I have a theory so tell me what's wrong with it. So assuming the universe is infinite and it continues to expand, as it expands the force of gravity between objects will lessen and eventually matter will no longer have a...

(I hope this is the right subforum) I'm talking about the series 1, 1, -1, 1, -1, 1, -1... I thought about it for a long time but I have no idea. If that first term were gone it would just be (-1)^(n+1), but...it's there...

Model describes universe with no big bang, no beginning, and no end http://phys.org/news199591806.html << complete quote of linked article deleted... please don't do that! >> http://arxiv.org/pdf/1007.1750v1.pdf

In iron and/or b12 deficiency, once levels of b12 and Ferritin have normalized. How long does it take for the MCH to return to normal ranges?

When our universe first started to expand, is it safe to assume that the energy inside of the expanding universe was traveling at the speed of light?

Okay, so, I'm about 2 semesters from completing my AA degree and I decided a couple semesters ago that I really want to be a math major. I am not a traditional student exactly - I was homeschooled and my math education was not strong, so I ended up placing into Intermediate Algebra in my first...

Hey. Yo I made a theory of how the universe began just by my self. here goes. i need feed back :D So we have black holes right? And in every center of a galaxy we have a large monster black hole. So virtually all galaxies are doomed to be food for a black hole. So in a very very...

The Higgs mechanism and the Beginning of the Universe Now that the excitement about the discovery of the Higgs particle has made the Higgs mechanism justly famous, could someone please clarify for me the implications of incorporating this component of the Standard Model of Particle Physics...

Because it take about 3 generations of stars to build enough carbon to the point where life is possible, roughly 9 billion years, our Earth therefore was among one of the first planets that housed enough carbon to make life possible. Stars will continue to exist for hundreds of billions of...

Hi, I am currently a beginning engineering student. I'm thinking mechanical engineering, but nothing is really set in stone. I am trying to spend a lot of this summer exploring different aspects of engineering and actually go out and go through the entire engineering process of designing...

That's title of the paper I've linked below. It's small paper that argues against an eternal universe. http://arxiv.org/pdf/1204.4658v1.pdf I'd like some opinions on the paper. It seems interesting. although the argument for the geodesic incompleteness of the eternal inflation model is not...

Hey everyone, What is a really good Physics textbook for one who has Geomerty, Alg II, and some Pre-Calc/Calc skills. Also, what is a really good Chemistry textbook for one who has Geomerty, Alg II, and some Pre-Calc/Calc skills. It would basically be an intro to classes, I'm just...

Hello, I am looking for advice on which version of Halliday and Resnick Physics to get. I am currently wondering if it would be wise to go for an early version of the text. I ask this because I've been self learning calculus from Calculus and Analytic Geometry by Thomas (Alternate ed, basically...

I am a freshman in High school, however I've been working quite a lot in the field of number theory for quite some time. However, I've been beginning to feel slightly bad that I haven't actually proven anything. It's not like I want to make a brand new theorem, no; but I would like to start to...

Persistence length: What are the beginning and end points in an polymer? Hello, can you tell me where the starting point and the ending point of the (parts of the) persistence length in a polymer are? I thought the persistence length was the greatest length that only just is not bent...

Can somebody please tell me what are the necessary math and physics prerequisites to having a solid foundation in quantum mechanics? And what are the most important concepts as well?

I'm a beginning calculus student and this is one of the 'challenge' questions from an older edition of the Stewart's Calculus series of textbooks. I believe I did the question properly, but the solution in the book is completely different from my own attempt. I'm not good enough at math yet...

Homework Statement Assuming that ∅ is a differentiable scalar valued function and F a differentiable vector field, derive the following identities. a)∇(dotted with)(∅F) = ∇∅(dotted with)F + ∅∇(dotted with)F b)∇(crossed with)(∅F) = ∇∅(crossed with)F + ∅∇(crossed with)F Homework Equations The...

I would like to know more about the beginning of time in terms of entropy. How can we explain the formation of a more ordered universe from a more ordered condensed structure that exploded and evolved to what the universe is right now? Where did the gravity come from and what is it's effect in...

I was looking through this neat math book I had when I was younger that listed the greatest mathematicians of history. I'm talking old, it's kind of funny because I liked mathematicians when I was younger because my favorite character on Jurassic Park was a mathematician and that's why I asked...

Hi everyone, I am beginning my freshman year at UC Davis in the fall. I am a double major in Evolutionary Biology and Chinese. I really struggled with math in high school (C- in both precalc/trig and AP stats). However, I am required to take 3 quarters of Calculus (More specifically, Math...

I don't know if this is the right topic to post this, so if it isn't please point me in the right direction. Ok so I was watching a video on SixtySymbols and they mentioned a picture from the Hubble called Deep Field. And talked about how in that image you are able to see objects from around...

Homework Statement A racket ball is struck in such a way that it leaves the racket with a speed of 5.37 m/s in the horizontal direction. When the ball hits the court, it is a horizontal distance of 2.15 m from the racket. Find the height of the racket ball when it left the racket...

Homework Statement 2 blocks are suspended on the sides of a table, over pulleys, connected to a central block on the table. From the left to the right, the masses are 4kg, 2kg and 6kg. There is a friction coefficient of 0.12 on the middle block. Find the acceleration. Homework...

Late last night, I got an email from the APS news thing (American Physical Society I believe). I'm a member, so no doubt those of you who are also members got this email. For those that didn't, here it is: Just to give an overview if you didn't read it all, there are some major cuts being...

Hi, I will begin studying calculus this or next week. I'm registered for the online version of U of Wisc's Calculus and Analytic Geometry. It's the standard, non-honors class, so we're using Thomas and Finney. Because I foresee wanting a deeper understanding of the subject, I will also be...

Okay I am a high school school student trying to learn the components of relativity, but i can't find anything that really explains any of it with examples and actual numbers. Does anyone know of a good place to learn this? I just feel stuck with high school education in the field of physics.

Homework Statement Consider a low-pass filter with RC=2x10-4 s. a) Calculate the -3db frequency for the filter. b) By what factor will the amplitude of a 10 kHz input sine wave be reduced by the filter? c) By how many db will the power be reduced by the filter at 10 kHz...