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Posts Tagged ‘Physics’

Vanishing point.

Vanishing point.

The classic example of describing the expanding universe is the inflating balloon.

Imagine that you are on the surface of a half inflated balloon. As the balloon expands you see everything around you moving away even though you are not at the center. If you move around the balloon everything will still be moving away, there is no special center. The two dimensional surface of the balloon is expanding into a three dimensional space for ease of understanding. Likewise one could imagine our three dimensional space expanding into an embedded four dimensional space.

This analogy never really worked for me. I knew what the expanding universe meant but I don’t see how the balloon is the best way to explain it. I heard a better one recently in one of my classes.

Everyone in the room is standing (or sitting) on a particular floor tile. Imagine now that there is an explosion in the room that causes all the floor tiles to fly apart. If someone is at the center they would see everyone flying away from them. But someone sitting elsewhere in the room will see that same person flying away from them. Similarly everyone will see everyone else moving away from them while they are stationary. Except it is not the tiles that are moving apart but space itself.

Of course all of this would easier if we could easily visualize four dimensional space (like a hypercube or 3 sphere).

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Stencil graffiti on the grey door faces a Shephard Fairey poster across the street,

Stencil graffiti on the grey door faces a Shephard Fairey poster across the street,

My physics department has a room dedicated to physics undergraduates as a study room. In the room there are two rows of computers, blackboards on opposite walls, a few comfy chairs, two large desks (about a dozen seats each) and a constant scattering of undergraduates. Often there are non-physics majors in the room but these are scant in comparison with the number of physics majors and occasionally grad students who breath often the air of this room.

In this room conversations evolve that would not flourish in any other environment. Today and in the future I hope to capture some of the topics that came out of the this mixture of stress, frustration and physics.

Can dolphins communicate or see at relativistic speeds?

Are they blind due to the sound never catching up with their target? If it could catch up would the location be so distorted from length contraction that it would become a jumble?

Would not the vacuum kill them first?

If they had special dolphin spacesuits could they communicate through radio? Could echo location work through a radio and would a dolphin be able to compensate for the speed of light?

Or would PETA shut down this experiment before we could finish building our Sub Orbital Porpoise Launching Apparatus?

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Boston had a lot of good reflective buildings.

Boston had a lot of good reflective buildings.

Today I volunteered for Spring Insight, the weekend where prospective high school students can come to campus and learn more about majors, colleges, activities and student services. Plus a whole host of events and presentations.

It was great, I got to spend all morning and the first part of the afternoon talking to people about physics, how awesome it is and why they should come here. Sometimes they stayed for only a few minutes but some we cornered and talked at for a good twenty minutes about what it is like at UCSB and why they should come here.

Initially I was only going to be there for half the event but ended up staying the entire time as I was enjoying myself; part of it was that I was essentially just hanging out with friends in the enjoyable sunlight.

I finished the the volunteer work off with a nice nap in the afternoon. The start of the quarter is always rough.

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Study Plan

Well, this was supposed to be posted yesterday but with the new WordPress interface I guess I hit the wrong button. I didn’t notice it not going up since my backup software was able to grab it just fine.

A view from my lecture room last year.

A view from my lecture room last year.

Today started my finals week, I started the long journey of studying. Lucky for me I have taken enough physics finals to know what I need to learn and how to go about doing it.

Essentially every physics class with few exceptions allow for a single sheet of paper worth of notes. So I use the act of writing the notesheet to be my study plan. I break it down into several steps:

Go over my notebook for the class and write down major topics, equations, themes and general knowledge that was learned in lecture. Then I go over any notes provided by the professor, the textbook, past exams and homework solutions to create a list of every important topic of the quarter. I have a habit of writing the word “final” in the margins if a teacher emphasis a particular equation or example in class, or if they flat out say this problem will be on the final. I add those to my list.

I then take my list and structure it into cohesive topics and related fields. At this point I write out everything I listed, based on either my notes or the textbook depending on which notation I have been using for the year.

Sometimes when I finish it all fits on one piece of paper, if not I write it smaller or start to cut things out. In the end I get a single sheet of notes for the class that I can take in for the final. If  a class does not allow note sheets then I now have a note sheet of things I need to know really well.

Depending on the class (and how I did on the homework) I sometimes do extra homework or past exam problems using nothing by my notes and a calculator (if allowed on the final). If I find myself needing something I then add it to the right section of the note sheet and continue on.

This method works for me since I learn best by writing things down as I hear them or in the case of studying think about them.

I don’t know how well this would work for other topics that have a large amount of information that needs to be memorized, math it would probably still work and perhaps engineering. One of the reasons that I like physics is that for the most part a small set of equations is all that is needed to answer most questions.

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Some cities have all the good ruins.

Some cities have all the good ruins.

Over the past few weeks, especially since the end of the Physics GRE, my spare time has been spent working on my personal statement. I feel that the personal statement is one of the hardest parts of the application process, not because of innate difficulty, but because it is the only part that can be tangibly changed while applying. Other parts such as the GRE, letters of recommendation, research experience and transcripts are all cumulative events that are difficult to wildly influence towards the end. But the personal statement can be changed dramatically until it is submitted.

Getting started was the hardest part. I found some resources online about personal statements in general. I went to a career services class on writing personal statements and I tried to gleam some information from the prompts themselves. To be honest these things sort of helped or will help when I am finalizing but none really sparked me into writing. Then again this is not something that can be dived into without any sort of preliminary work.

The best way that I brainstorm is with web diagrams, writing something down in a circle then branching off of that with more words until a web of ideas form. At least it helps when I have no idea what I am doing. Luckily I found a neat free application to help with this called FreeMind. It is open source and runs on all operating systems and has really helped me organize what I want to write about.

To start I created branches listing what I am interested in studying, what skills I have, my experiences and then structural features of my personal statement. Once I wrote this stuff I collapsed those branches and never really looked at them again (well once just now). I sections filled with questions from various personal statement resources from Career Services at my school or the internet. Just the questions, no answers to any of them.

I also asked one of my professors for his advice on personal statements as he was on the graduate admissions committee. He did say that personal statement do not matter that much, but other sites online (like physicsgre.com) have professors giving the opposite advice. But talking to a professor really did help. Essentially he said to show in the statement several things: I am ready to do research, I enjoy lab work, I know what I want to study and how this department fits with what I want to research. The things is to show that the writer is on top of things and not just randomly applying in order to put off real life.

Once I organized all of the advice and tips I started writing. Not the personal statement though. I mentioned that I some advice sites list questions to help getting started (I forgot where I found mine otherwise I would link to it), I answered all of those. Or at least all of them. Some I did answer but it was more of a venting thing then a real answer. Answering these questions help in that they let you start to find your voice for the personal statement. Since I already write a bit (this blog and journals) I already know what my voice reads like so it was not much of a problem. But if you are unused to writing, especially about yourself, then answering these short snippets will help.

Finally I wrote my first draft. To get started I did the whole thing as a free write where I kept on writing. In between solid paragraphs I wrote comments or just superfluous statements about the process. The key to a free write is that it is much easier to correct and edit then it is to create.

I have not gotten past the first draft, I need to give it at least twelve hours to brew. The next step is too start correcting, filling in gaps, transitioning and structural work. Once a readable draft is ready I will send it to a lot of people to look over, critique and edit. Since every school requires something different I will then edit, alter and adapt my one good statement for the schools.

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The Physics GRE

 

More Keukonhof Flowers

More Keukonhof Flowers

After a strenuous week and a half of study I took the Physics GRE this morning. It was a great use of a Saturday morning. The actual exam did not differ from the practice test in difficulty or content. 

Now there is a six week wait while this 100 question scantron test is graded. I suppose it is being graded by hand. I realize that they need to compile all of the tests together in order to compute the right percentile and to compare it to past exams but I feel that there might be a modern piece of equipment that could speed up this endeavor.

In the end six weeks is a good length of time to separate myself from the test and the results. While it was satisfactory to know my results immedietely afterwards for the general GRE a nice gap does help soften the potential disappointment.

Six weeks or in all likelihood January sometime I will find out about my Physics GRE. Until then all my graduate school dedicated time will be spent on the personal statement. Even more fun.

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Not quite a running fence.

Not quite a running fence.

I did more studying for the Physics GRE this weekend. I created a study sheet based off of the physics I missed on the first practice test, I then studied that before the first practice test I took on Saturday.

Like the first practice test (GR0177) this one (GR9677) also destroyed me, my score only went up by 10 to 600. Not quite my goal.

So I went over what I did wrong like the first test and this time I completely rewrote my notes into a clear organized format. After a day of looking it over between doing other things (like laundry and personal statements) I took a third practice test, GR9277.

This one went loads better. I think I am starting to get the hang of when to omit a question instead of guessing, how to read the questions and not screwing up on the basic math. For the third test I got 720.

I have just one more practice test between me and the actual exam this Saturday. I want to get at least another 720 for consistency or my ideal score of 800.

If only this school stuff did not keep getting in the way.

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Physics Joke

 

Conservation at its best.

Conservation at its best.

Sorry if I offend anyone with this joke, but it needs to be said.

So this Positronium couple walks into a bar, and as they walk in a Photon walks out.

As the Photon leaves, the bartender, being a conservative guy, yells:

“Hey! You forgot your Neutrino!”.

To which the Photon replies:

“What am I? A Muon?”

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This piece just spoke to me.

This piece just spoke to me.

Build transistors same

otherwise

bad mirror

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Construction at UCSB, there is always some on campus.

Construction at UCSB, there is always some on campus.

I started studying for the Physics GRE today. My test is on November 8th, I know I should have started sooner. It sort of snuck up on me.

I don’t know how most people would start studying. Maybe looking over notes for the past years or reviewing a lower division general physics textbook. Or internet resources. I decided to go full immersion and start with a practice exam.

It destroyed me.

In the end my score came to be 590 or about 34th percentile. My goal is about 800 for the schools I want to get in to. During the test I marked problems that I felt I needed to review, sadly no correlation appeared between the problems I marked and the ones I answered correctly.

Now I need to decide on a path of study before my next practice test (probably Saturday). I can either look over the test for the right answers, look at solutions for my wrong answers online or compile a list of topics to study from notes.

I will start with solutions then move on to notes. Let us see if my score improves after my next practice exam.

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