Skip to main content

Dark Matter



Dark matter is believed to make up approximately 27% of the known universe. However the magnitude of this estimation cannot fully be understood unless one also understands that all matter familiar to humans makes up only about 5%. This is one of the many realizations that tell us how profoundly little we know about the universe we live in.

But what is dark matter? For many its name conjures up thoughts of deep space and sci-fi movies, and in reality, no one can really be sure whether or not those images are accurate.

Dark matter is characterized by its inability to be detected by any of the human senses. This is due to its lack of electromagnetic interaction, i.e. it cannot or does not reflect, give off, or absorb light. Granted no one has ever attempted to taste or smell dark matter, but so far everyone seems accept the fact that it is for the most part imperceptible.

With the knowledge that dark matter itself it imperceptible to humans, it is impossible not to wonder how exactly scientists know of its existence. First, dark matter's existence is said to be "inferred." While this word may provoke connotations of uncertainty, the vast majority of specialists are reasonably certain of its existence. Their confidence comes from dark matter's gravitational influences throughout the universe, which are highly inexplicable without the inference.

Essentially, scientists observe dark matter through galaxies that rotate at rates that are highly unsustainable by their orbital axis/center of gravity. To use an analogy, this would be like earth revolving around the sun at a rate three times its normal speed, despite the sun's gravitational limitations. If the Earth were to increase its orbital speed drastically, the sun's gravity would no longer be able to sustain Earth's orbit due the principle of Newton's second law applied to rotation: F=mv^2/R. After using this same principle in certain other galaxies, scientists noticed that certain planets were moving far too fast to be held in orbit by the gravitational force of their suns, which as we know is equal to Gm1m2/r^2. The model below shows how the calculated velocities did not match those that were observed.

Image result for dark matter



This realization led scientists to delve deep into the fundamentals of physics, only to come to the conclusion that the gravitational pull of an unknown substance must be acting on these planets to keep them in orbit. Thus dark matter was inferred and research and new breakthroughs continue to be made about it today.


https://home.cern/about/physics/dark-matter
https://www.space.com/20930-dark-matter.html
https://www.scientificamerican.com/article/what-is-dark-matter1/
https://www.popsci.com/sites/popsci.com/files/styles/1000_1x_/public/import/2013/images/2011/12/Rotationcurve_3.jpeg?itok=ltCRS7yQ

Comments

Post a Comment

Popular posts from this blog

The Physics of Spiderman

Over this past weekend after I finished working on my homework, I decided to relax and watch a few movies before going asleep. Among the movies I watched was Spider-Man 3 from 2007 and despite the movie flaws I was interested by the scenes that showed Spider Man shooting through the sky with the use of his webs that come out of his wrists. Due to this, I decided to make my blog post about the physics of Spider-Man's slingshot. After doing some research, I discovered just how much information there is on the physics of Spider-Man and how elements of Spider-Man can be used as examples for most topics learned in mechanics. For this investigation, I will not be using the horrible cliche and terrible CGI infested mess that Spider-Man 3 is but instead the all around superior Spider-Man movie of Spider-Man 2 to investigate the physics of Spider-Man's web propelled slingshot.  I want to talk about what happens in terms of physics when Spider-Man launches himself across a dista...
Post a Comment
Read more

Physics of Sound Dampeners and Active Noise Cancellation

Physics of Sound Dampeners and Active Noise Cancellation Sound dampening foam panels in a recording studio. ANC headphones worn by pilots and/or passengers in consumer aviation aircraft.  Acoustic treatment of soundscapes has grown alongside the sound production industry. Whether through absorption panels, diffusors and cloud panels to treat a space or headphones placed directly over the ears of listeners, acoustic treatment comes in many forms. Environments are treated acoustically to absorb excess sound to prevent sound levels from crossing a threshold above which the desired goal cannot be had. Before getting into sound dampening, we must discuss sound. Sound is produced when an object vibrates (a form of oscillation) and temporarily displaces nearby air molecules causing a wave effect as the displaced molecules collide with their neighboring molecules. Sound waves are fluctuations in pressure as the initial displacement of molecules experiences collisions that in ...
Post a Comment
Read more

Physics Behind Drone Flight

A drone flies by using its downward thrust and forcing air in a particular direction in order to sustain a certain speed as well as a specific height. In this video my friend and I had been flying a drone at exactly 4 mph which converts to 1.788 m/s. In this project, we will be determining the forces acting upon the drone in order to sustain a consistent flight in terms of velocity and height while excluding the effects of air resitance. The drone is flying at an angle of 28˚, this is found by extending the tilted axis of the drone to the horizontal and finding the angle with a protractor. From this angle we will be able to calculate the downward thrust and the acceleration of the drone that allows it to maintain its height and velocity during flight. When the mass of the drone is taken it results in 734 grams or .734 kilograms, which will also be used for the calculations within the project. The freebody diagram pictured above will alow us to derive the force equations f...
Post a Comment
Read more