2017 Physics Nobel Prize for Discovering Gravitational Waves

As of 6:30 EST the 2017 winners of the Nobel Prize in physics were announced! The winners were Rainer Weiss, Kip Thorne, and Barry Barish. Weiss is a professor at MIT while Thorne and Barish teach at Cal Tech. They won the Nobel Prize because they were the first physicists to observe gravitational waves, or space-time distortions. These gravitational waves are believed to have originated from the collision of two massive black holes over a billion light years away!

Even more astounding is that this discovery confirms Einstein’s General Theory of Relativity, which he formulated 100 years ago without the sophisticated technology we take for granted today. His theory states that matter and energy would warp the geometry of space-time, producing gravity. This theory has numerous implications. His equations predicted that the universe was expanding from what we call the Big Bang. In this case, it predicted that massive objects like black holes would create ripples in space-time. The energy released from the collision of these black holes is still spreading outwards via these gravitational waves, which can stretch and compress space in a manner similar to how sound waves compress air. However the farther these waves travel the shorter the motion of their stretching and compressing, and, the harder they are to detect. We can think of the stretching-compressing motion of these waves the same way we think of our spring force (F_S). After we stretch out the spring to its maximum potential energy, it begins to compress and stretch until it eventually runs out of kinetic energy. Thinking about the magnitude of energy emanating from the collision of the black holes, and the wide expanses of the universe they travelled to make it here, makes humanity seem so insignificant in the grand scheme of the cosmos.

So how could these physicists detect such a cataclysmic event that occurred billions of years ago? They developed LIGO: The Laser Interferometer Gravitational Wave Observatory. The LIGO detector has an L-shaped antenna with arms 2.5 miles long that contain mirrors made from ultra-pure glass at each end. The laser is split and sent to the mirrors of each arm and measures the distance between the two. If the arms are precisely the same length, the returning beams cancel each other out and no light is detected. But, since gravitational waves move in a stretching and compressing fashion, if one passed through the Earth, it would stretch one mirror and compress the other one. In this case, a discrepancy of one part in a billion trillion, a fraction of the width of a proton, misaligned the beams, causing the detector to record a rhythmic pulse from the wave. The future implications of this research are extensive. We can learn more about the big bang and the inception of our universe!

It’s also so interesting to learn about gravitational waves in the context of what we learn in class. We typically have only considered gravity as a force that dictates kinematic motion. However, the discovery of these gravitational waves poses this idea of an all-encompassing record of the history of space-time, and our universe.

https://www.nytimes.com/2017/10/03/science/nobel-prize-physics.html

Potential Energy Changes in Wedding Dancing

My dad is known for being an entertaining dancer who stops and starts as he pleases and bops up and down or side to side. This past weekend it became even more apparent while we were at one of his college friends daughter’s wedding. While he was doing this I thought it would be interesting to see how his potential energy due to gravity changes as he bops up and down versus side to side. 

Let's set the ground as y=0. When my dad is standing up straight, since he is 5’11’, we set 71 inches as h. When he crouches his knees and bends down to “bop” his height drops to 65 inches lets say. Since the equation for potential energy is PEg = mgh, when he is standing still his potential energy is m x 9.8 x 1.8034 m. When he is crouched his potential energy will be less since his height is 6 inches lower. It would be m x 9.8 x 1.651m. The potential energy my dad has when he is crouched is less than when he is standing up straight and not moving. Theoretically this makes sense because potential energy is related to the energy of an object's position, not the objects motion. When he begins moving and starts lowering his h value, the potential energy decreases because he is moving his position. Since his position is lowering from the baseline, his "h" value decreases, lowering his potential energy value. 

Now let's consider the change in potential energy due to gravity as he shifts from side to side. When he shuffles from side to side, his height is still staying the same, as well as his mass and the affects of gravity which are still the same as before, so his potential energy does not change. If you think about this theoretically it makes sense. The potential energy due to gravity is not being affected by his movement in the x direction, just the y direction since it is the potential energy due to gravity. When using the equation PEg = mgh, the value of PEg will be the same no matter what the x component of my dad's location is. Thus, the change in potential energy is apparent when dancing in the y direction, but not from side to side in the x direction.

Physics of a Game Winner

The idea came for this post came from a social media post regarding a game winning field goal from the Eagles vs. Giants game this past Sunday. With no time left on the game clock, Jake Elliot kicked a field goal from 61 yards (tied for 7th best all-time), and just narrowly managed to squeeze the ball inside the right upright and over the bottom goal post. The post showed that Elliot had to kick the ball within a tight 5.8 degree angle. It related this to being the equivalent of kicking the ball into an 18 inch window from 5 yards out. For this blog post, I decided to look at both the accuracy of that post and how much speed he had to generate to put enough air under the ball for it to go the distance. Elliot kicked the ball from the the right hash, conveniently at a right angle to the plane formed by the goal posts (the hash marks and uprights are both 18 feet, 6 inches apart). This means that the tangent of the angle between which Elliot could have kicked the ball to win the game was equal to 18.5 ft divided by 183 ft (61 yds times 3 ft per yard). Upon checking, report accurately determined the angle, (5.77 degrees to be just a little more precise.) A little more trig shows that x/15ft=tan(5.8). 15*tan(5.8)=1.52, meaning that the report again was accurate in that from 15 feet away, the ball would have to squeeze into about an 18 inch window to be on target when it reached the goal posts! Pretty remarkable when you think about the fact that an NFL ball is 22 inches in circumference at its fattest point. Further, in order to determine the initial velocity he had to put on ball to get it over the 10 foot high goal post, via a direct line drive at the shortest possible distance (just over 183 ft). In this case again, we can look at right triangles to see that our total distance on the ground is 183 ft, and our elevation is at 10 ft. This means again that the inverse tangent of the height over the ground distance is equal to the hypotenuse, or the total distance the ball must travel. This comes out to a 3.1 degree angle if Elliot were to kick the ball so that it just skimmed the bottom right corner of the goal post on a straight line. Now using vf^2=vo^2+2a(xf-xi) we can determine what the exit velocity in the y direction would have to be, which we can use to find the overall initial velocity. vf= 0 at the peak of a curve, and vi is our unknown. The only acceleration on the ball after it is kicked is gravity at -9.8 m/s, and our xf=3.048 m (10 ft). This means that the ball must exit at 7.7 m/s in the y direction only. If you plug that into a sin(3.1 degrees)=7.7/hypotenuse, you can see that the initial velocity would be at least 142 m/s!!! Obviously, I have not taken wind resistance/drag into account, which does play a role no doubt, but the feat is impressive nonetheless.  In conclusion, Jake Elliot has a hammer for a foot,

 and lets go Birds!!!!!!

The Physics of Football: Beast Mode Edition

This Sunday, like most, I followed my routine of watching NFL games and keeping up with my fantasy football teams. While I was sitting on my couch watching 220-pound behemoths collide in the open field, I wondered how the motion of these players related to physics.

When it comes to running styles in the NFL, coaches consistently preach “north-south” running instead of “east-west” running to ball carriers. With respect to kinematics, coaches prefer their players focus on the y-component of their motion instead of the x-component. They focus on the differences between distance and displacement. If a first down is 10 yards and solely measured by a runner’s displacement in the positive y-direction, and the vector of the displacement of a runner is 10 yards east and 3 yards north, ultimately they are well short of a first down. Therefore, it is understandable that coaches preach “north-south” running because it allows runners to maximize their displacement in the y-direction, which is most important for gaining yards in the game.

Conversely, offensive linemen tend to move in a different manner. A lineman’s job is to move defenders to create running lanes for the halfback. Because of this goal, the motion of linemen can often have a more prominent x-component, as they are tasked with making contact with a defender and then angling them in either the +x or the –x direction away from the runner.

I wanted to particularly analyze the motion of Marshawn Lynch in his infamous "Beast Mode" run from the 2011 wildcard game between the New Orleans Saints and the Seattle Seahawks (video below). In the video, we see Marshawn Lynch rip off one of the most memorable runs in NFL history. If we look at the play below we can think of the motion of each player as a vector within an x,y coordinate system. We can see that the direction of the blocks from linemen and receivers contains a substantial x-component as they angle off defenders and create a hole for the running back. The vector of the halfback’s motion demonstrates a nearly vertical trajectory, following the “north-south” running style NFL coaches value. Thus, Lynch was able to grind his way to a touchdown by ensuring he runs in the +y direction and maximizes his displacement as he moves forward. 

http://www.nfl.com/videos/nfl-films-presents/09000d5d82217331/NFL-Films-Presents-Beast-mode

Theory of why the traditional gender gap exists in physics

There is not a doubt that there is a gender gap in most STEM fields, especially in physics. Australian academics have put forward an interesting theory about the gender divide in physics and hypothesise that it is because of "boys' fondness for urinating at targets." Due to this hobby, boys are able to understand force, momentum, fluid dynamics, and other key concepts of physics better. Although they cannot prove this theory without empirical evidence, they think that this "self directed, hands-on, intrinsically (and sometimes extrinsically and socially) rewarding activity must have a huge potential contribution to learning, resulting in a deep, embodied, material knowledge of projectile motion that's simply not accessible to girls."

They argue that physics is a difficult subject for girls because they lack the experience of grasping projectile motion first hand. It is usually taught in the beginning of physics courses because it is a relatable concept, like throwing a ball. Since boys stand up and have "playful urination practices," they may have an advantage over girls in understanding physics. They do offer more traditional explanations for the gender gap, like the problem of society associating logical and mathematical ways of thinking with masculinity, and some parents or teachers may inadvertently discourage girls from pursuing STEM subjects.

This study started because in the UK, 1/5 students who studies "A-level" physics is a girl. When conducting this study, they found the differences were pronounced when asking questions about projectile motion that focused on the velocity of objects that are thrown, kicked, or fired. In order to combat this gender gap, specialists have suggested changing the curriculum so that forces and momentum are not taught first, and to put a slighter emphasis on projectile motion. They don't suggest that girls also start "playful urination practices" but they do start with subjects like energy conservation, which they claim is more central to physics.

How the use of the iPhone 9 minute snooze button affects the speed of getting ready in the morning

I am a notorious alarm clock snoozer and in the morning that can leave me with a frantic 30 minutes or less to get ready for the day. I wanted to see how long it would take me to get ready without using the alarm clock snooze. I hypothesize that the shorter time I have to get ready the more steps I will take because I will start to get frazzled and try to do too much with the shorter time I have. This increase in steps and distance traveled but because I have less time the speed in which I get ready will increase from a morning that I do not snooze. For this experiment, I will be using my IPhone as a pedometer and as a stop watch. On Tuesday morning, I did not snooze the alarm and I got ready in 40. minutes. On Thursday morning, I snoozed the alarm two times and had 22 minutes to get ready.

Conclusion

The day I did not sleep in resulted in a 81 percent increase in time that it took to get ready compared to the day I slept in. I walked 40. percent more when I was rushed compared to my normal morning routine. Overall this lead to a 167 percent increase in speed. This increase in all areas seems to make sense because in the morning as time gets more constrained I feel myself becoming more frantic. This leads me to start going out of order in my routine and running around with no purpose. This unnecessary movement and the already constrained time leads my speed in the morning to be increased by almost three times my morning routine.

Physics of Star Wars book explores the science of the force (and gungans)

The first movie I ever saw in theatre was The Phantom Menace in 1999. I don't remember much of it because I was so young, but I do remember being fascinated by the light sabers and, although the CGI technology was no where near as good as it is now, it still amazed me. How cool would it be to live in a world where we could travel at hyper speed through space, and we could have light sabers to fight with. Now with technologies like the hyper loop coming to play, maybe we aren't so far from the sci-fi universe that we all dreamed of as kids.
This article speaks about the "tantalizing and impossible" physics behind Star Wars, evident in the use of the light saber and hyperspace travel. Professor Patrick Johnson wrote the book The Physics of Star Wars to explore if the physics is close to becoming reality. This book will be released November 7, 2017, but is not the first time that a scientist has tried to grapple with this idea. For example, in 2016, Mark Brake and Jon Chase wrote the book The Science of Star Wars: The Scientific Facts Behind the Force, Space Travel, and More! along with several other similar publications. 
Each chapter explains one phenomenon, how it fits into Star Wars, and then how it works compares to the physics that we understand in the real world. 
The example the article draws on is that there's one chapter about machines making machines, which seems like a soon reality since we already have 3D printers and automated manufacturing plants. 
Circling back to The Phantom Menace, they travel to the core of Naboo, and when they do this, the movie implies that Naboo is water from "surface to surface," and it is possible to have a planet like that, but has certain implications that Star Wars did not entirely consider. For example, the water at the bottom would be under high pressure, and more likely to freeze since the boiling points of water change with pressure. And now that you consider that, will the radius of the planet be affected by that? He said, "If you go to the perfect center of a planet there's no force of gravity because on all sides it would be pulling it towards it, so there's no force of gravity. This means that the pressure behaves in a more complicated fashion as compared to my initial approach." And then, if Naboo was truly water at the core, then it wouldn't have the iron core or a magnetic field, but then maybe the inhabitants set up a magnetic field on their own, or they are super resilient to radiation. 
Physics in pop culture is incredibly interesting and I'm so excited to read this book!