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

Physics of Black Holes...Or Lack Thereof

Isabella Jacavone To comprehend how the universe works, we must dwell into the most basic building blocks of existence; matter, energy, space, and time. NASA's  Physics of the Cosmos program involves cosmology, astrophysics, and fundamental physics intended to answer questions about the elusiveness of complex concepts such as black holes, neutron stars, dark energy, and gravitational waves. In this blog post, I'd like to elaborate on a subject that is very intriguing  to me; Black holes. And more specifically, what would happen if we got near one. A black hole is anything but a hole, but rather an immense amount of matter compacted into an extremely small area. A black hole is caused when, hypothetically, a star four times more massive than our sun collapses into a sphere no bigger than 600 square km. To put that in perspective, that's about the size of New York City. B lack holes were predicted by Einstein's theory of general relativity, which showed that when a...
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

The Physics Behind the Rail Gun

Magnets and Magnetic Fields: Magnets are well known for their ability to repel and attract other magnets and various pieces of metal, but what people seldom understand are the physics at work that cause such occurrences. Magnets are everywhere, from within TV's and cellphones, to the Earth itself, and they are all producing magnetic fields. For a particle, a magnetic field can be defined to be "a vector quantity that is directed along the zero- force axis" with a magnitude equal to the dividend of the magnetic force and the product of the particle's charge and speed, and for a bar magnet, the field is best demonstrated as arcs going from one pole to the other. With that said, magnetic fields can also be created; the basic principle of electromagnetism is that the movement of electrons through a conductor produces a magnetic field in the region around the conductor. This is the fundamental principle behind the workings of the rail gun. Unlike a bar magnet, a ...
Post a Comment
Read more