Month / September 2018

by ams9006

What Goes Up Must Come Down

What goes up must come down, except for spacecraft. Some tend to keep going up, or at least stay up for a long time. However, all of the spacecraft, satellites, and junk in earth orbit still comes down. In fact, they have, are, and will always be on their way down. Everything in orbit is falling, because everything in orbit feels the gravitational pull of earth.

Based on our cultural knowledge we accumulate from media here on earth, it appears as if there is no gravity in orbit. The incredible pictures and videos we are given by NASA and other space travel organizations paint a picture the of harsh, yet serene silence and stillness of space, where everything is so isolated and untouchable that not even gravity can displace it. However, despite the fact that everything in space appears to hover and not fall to gravity, that is not the case. Everything in orbit is under the influence of gravity, and it’s all falling.

Why is reality different from perception? Wikipedia put it best: “objects in orbit are in a continuous state of free fall, resulting in an apparent state of weightlessness.” Everything in the International Space Station is falling just as quickly as the International Space Station itself is falling. Just as you feel weightlessness in a falling roller coaster, so do astronauts and cosmonauts in the falling space station.

So why has the space station been falling from an altitude of 250 miles for 20 years and never hit the ground?

Because it’s going insanely, ridiculously, crazy fast. Specifically, the space station is floating along at about 7.67 kilometers per second, or 17,200 miles per hour. This is over 22 times the speed of sound and fast enough to orbit the earth every hour and a half. This means that falling, in the traditional and logical sense, does not apply here.

https://youtu.be/Xjs6fnpPWy4?t=1m25s

a real-time video demonstrating the International Space
Station's one and a half hour orbit period

To illustrate this, compare the International Space Station to a ball tied to a string.

a rather colorful, round space station (source)

When the ball is spinning around, there is a constant pulling force toward the center of the circular path. However, because the ball is constantly moving forward, the force only shifts the direction in which the ball is travelling. The physics students among you would recognize this as centripetal acceleration; those of you who haven’t taken physics would recognize this as really boring.

What’s not boring is that the International Space Station undergoes the exact same process on an almost unimaginably ginormous scale. It experiences 90% as much of the pull of gravity as we feel down on the surface of earth, but it is just going so fast that gravity does not pull it down to the ground, but just around, leading to a circular path around the planet that we simply call orbit.

by ams9006

Why Is My Computer Slow?

If you’re like me, you spend a lot of time on the computer. You have years upon years of experience using computers, and you’re approaching light speed at completing digital tasks. However, your computer is not. Every time you start it up, your computer does its best attempt to mock and imitate the way you wake up on a Saturday morning, taking far too long and trying to convince you to just let it go back to sleep. However, computers aren’t people; they don’t get tired (unless they run out of battery). Why are computers so slow?

It may appear at the surface that a computer is simply slow because the processor is outdated and the computer needs to be replaced. However, there are several ways in which a computer can be lacking the resources it needs to perform. One of the most common reasons that a computer is slow is not because the processor (often described as the “brain”) is slow, but rather because the storage device is slow.

Storage devices for personal computers come in many shapes and sizes. In the ancient past (read: a few years ago), data was stored on floppy discs. These were large, had capacities measured in kilobytes or megabytes, and most importantly, had bandwidths of about 1 Mb/s. Until recently, most storage was on hard drives (or hard disc drives, or HDDs), which were 100 times faster than floppy discs and had 10,000 more storage capacity. Keep in mind that the time span between these technologies was only a decade or two; technology improves significantly every year.

Today, most devices run on solid state drives (SSDs). These run on a fundamentally different type of technology. While CDs, DVDs, floppy discs, and hard drives all operated by writing and reading from spinning discs, solid state drives read and write from transistors. Thus, they are solid state because there are no moving parts, which makes them far, far more durable than previous mechanical forms of storage. However, that is not the main reason why they are used today.

We use them because they are crazy fast. Obscenely fast, even. They’re fast enough to transcribe the entirety of the English language Wikipedia in under a minute. They are obviously more expensive than hard drives, but computer manufacturers have learned that this is the feature that makes their computers feel fast.

This video demonstrates the real-world impact of an SSD

There still are applications which require large amounts of processing power; professions in the sciences and digital arts require professional (expensive) computers to do the job. However, most users don’t synthesize new data and content on their computers; they are simply looking to retrieve data that already exists on their computer or on the internet. They turn on their computer, check their email, watch videos, move documents, search the internet, and turn off their computer. All the computer is doing is shuffling things around, whether from the internet to the computer or from the storage drive to the user’s eyeballs.

That is why having a fast storage drive is important. If your computer is slow, it’s probably because your computer uses a hard drive. Fortunately, upgrading a hard drive to a solid state drive is as simple as backing up your data, unplugging one small metal rectangle, plugging in the new slightly smaller metal rectangle, and re-downloading the backup.* However, that’s a blog post for another day.

*it’s actually a bit more complicated than that
by ams9006

How 3D Printing Works: Explained in Under 500 Words

3D Printing is just like 2D printing on regular paper.

Why is that, you may ask; isn’t 3D printing by definition totally different, introducing a whole other (excuse me) dimension of technology and complexity? How are they comparable?

On a “normal” paper printer, a user first sends the file they want to have printed from the computer to the printer. This file is a two-dimensional image or document; on a 3D printer, the file is a three-dimensional model. However, the process is the same.

The printer (2D or 3D) does not know how to interpret an image, document, or 3D model because it is simply a connected collection of motors, nozzles, and buttons. It is the computer that interprets these files and translates them into specific instructions for the printer to follow. For example, the first commands given a paper printer would be to bring a sheet of paper down to the print area and to move the nozzle to the top left corner of the sheet.

When a paper printer receives these commands, it proceeds to move its ink nozzle around the surface of the paper, depositing ink in the predetermined pattern to form the image provided by the computer. In the same way, a 3D printer simply interprets the commands by moving its nozzle across the bed of the printer and depositing plastic in the predetermined pattern. (3D printers have to melt their plastic as they are placing it though.) However, unlike a paper printer, the 3D printer does not spit out the page after drawing the image on the bed of the printer. Instead, the plastic laid on the bed of the printer becomes the new “paper” or printing surface, and the printer continues to deposit another layer of plastic.

The many layers of plastic needed in a 3D model

The image formed by each layer of plastic can be thought of as a “slice” of the 3D model. All of these slices joined on top of each other forms the product, a functional plastic object.

Just like with 2D printers, 3D printers can print in different colors. However, not only can they print in different colors, they can print in different materials as well. Different plastics have different properties that are desirable for different applications. For example, if I wanted to print a tire for an RC car, I would use flexible filament for its rubbery texture that can grip many surfaces.

The way I see it, 3D printing can do everything that paper printers do and more. This comparison applies to the end use of the products as well. Printed paper is used to store, share, and display information and images. 3D objects do the same thing; there are 3D printed art pieces and educational models all over the internet. However, plastic isn’t just used to make art and information; it can be used for functional purposes as well. This is the magic of 3D printing: you can think of an object, search for it online to try and print it, not find it, make it yourself, and have it, all within an hour.

Edit: Due to unforeseen (see: predictable) circumstances, this explanation has surpassed 500 words. I apologize for any inconveniences caused.

by ams9006

Preface

Albert Einstein once said, “if you can’t explain it simply, you don’t understand it well enough.” In these blog posts, I will do my best to simply explain topics that (I think) I understand. These posts will serve to inform you, the reader as well as improve my own knowledge on the topic at hand.

Most of the topics will probably relate to my personal (non-academic) interests, including computer building, 3D printing, cello playing, and many others. If any of these topics are unfamiliar to you, I hope that through this blog you may find that some of these things are less intimidating than you thought.