- published: 14 Mar 2018
- views: 21
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A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light. Whether light is affected by gravity under Newtonian mechanics is unclear but if it were accelerated the same way as projectiles, any light emitted at the surface of a dark star would be trapped by the star's gravity, rendering it dark, hence the name. Dark stars are analogous to black holes in general relativity.
https://en.wikipedia.org/wiki/Dark_star_(Newtonian_mechanics)
Please support this channel and help me upload more videos. Become one of my Patreons at https://www.patreon.com/user?u=3823907
Get more lessons like this at http://www.MathTutorDVD.com
Learn about the acceleration due to the force of gravity in this lesson on gravitational acceleration. Here we explore why objects fall at the same rate in a gravity field. You will first learn that the acceleration due to gravity is the same for an object of any mass.
Next, we explore the modern theories of physics to explain why an object experiencing a larger gravitational force should accelerate at the same rate as an object with less mass. We review Einstein's thought that inertial mass equals gravitational mass for any object. We further explore that in Einstein's Theory of General Relativity, objects simply follow straight paths through a curved space time continuum.
The falling objects we see as the force of gravity is just a geometric effect of all objects trying to follow a straight path in a curved space.
- published: 15 Oct 2018
- views: 36050
A fan asks if Modified Newtonian Dynamics, a theory that attempts to explain the missing mass in the Universe without resorting to the existence of dark matter, is credible, or is it pseudoscience? To answer this Cosmic Query, Neil deGrasse Tyson explains MOND, as astrophysicists call it, to co-host Chuck Nice, touching on dark matter, dark gravity, and Newton’s Laws. But is it pseudoscience? No spoilers here: watch and learn for yourself.
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Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up!
#StarTalk #NeildeGrasseTyson
- published: 22 Jan 2015
- views: 33647
In physics, "modified Newtonian dynamics" is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies. Created in 1983 by Israeli physicist Mordehai Milgrom, the theory's original motivation was to explain the fact that the velocities of stars in galaxies were observed to be larger than expected based on Newtonian mechanics. Milgrom noted that this discrepancy could be resolved if the gravitational force experienced by a star in the outer regions of a galaxy was proportional to the square of its centripetal acceleration , or alternatively if gravitational force came to vary inversely with radius . In MOND, violation of Newton's Laws occurs at extremely small accelerations, characteristic of galaxies yet far below anything typically encountered in the Solar System or on Earth.
MOND is an example of a class of theories known as modified gravity, and is an alternative to the hypothesis that the dynamics of galaxies are determined by massive, invisible dark matter halos. Since Milgrom's original proposal, MOND has successfully predicted a variety of galactic phenomena that are difficult to understand from a dark matter perspective. However, MOND and its generalisations do not adequately account for observed properties of galaxy clusters, and no satisfactory cosmological model has been constructed from the theory.
Several independent observations point to the fact that the visible mass in galaxies and galaxy clusters is insufficient to account for their dynamics, when analysed using Newton's laws. This discrepancy – known as the "missing mass problem" – was first identified for clusters by Swiss astronomer Fritz Zwicky in 1933 , and subsequently extended to include spiral galaxies by the 1939 work of Horace Babcock on Andromeda. These early studies were augmented and brought to the attention of the astronomical community in the 1960s and 1970s by the work of Vera Rubin at the Carnegie Institute in Washington, who mapped in detail the rotation velocities of stars in a large sample of spirals. While Newton's Laws predict that stellar rotation velocities should decrease with distance from the galactic centre, Rubin and collaborators found instead that they remain almost constant – the rotation curves are said to be "flat". This observation necessitates at least one of the following: 1) There exists in galaxies large quantities of unseen matter which boosts the stars' velocities beyond what would be expected on the basis of the visible mass alone, or 2) Newton's Laws do not apply to galaxies. The former leads to the dark matter hypothesis; the latter leads to MOND.
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This video uses material/images from https://en.wikipedia.org/wiki/Modified+Newtonian+dynamics, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.
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Disclaimer: This video is for your information only. The author or publisher does not guarantee the accuracy of the content presented in this video. USE AT YOUR OWN RISK.
Background Music:
"The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library.
This video uses material/images from https://en.wikipedia.org/wiki/Modified+Newtonian+dynamics, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.
- published: 10 Sep 2015
- views: 1469
An alternative to adding dark matter to galaxies to explain the rotation velocity that is way too fast is to change the long cherished Newtonian mechanics in the regime of small accelerations.
Because the Modified Newtonian Dynamics (MOND) does not do very well for larger structures, and because there are systems that seem to need no modification of ordinary mechanics or that show a separation of the gravitation and the source, MOND is nowadays viewed less favorably than dark matter. But there is an important point that it gets right (by construction): it is as if the force law had one less power of r.
Based on preprint DOI: 10.13140/RG.2.2.35022.41289
available at Research Gate.
The research therein was partly funded by the spanish government under grant MINECO:FPA2016-75654-C2-1-P (Spain); Univ. Complutense de Madrid under research group 910309 and the IPARCOS institute. The author declares that he has no conflict of interest. This video is part of a public dissemination effort and involves no profit.
- published: 01 Oct 2020
- views: 76
Inspired by the recent image of the Powehi m87 black hole from the Event Horizon Telescope, I attempt to visualize the behavior or light (photons) following the path of spacetime around the black hole.
💻 Code: https://thecodingtrain.com/CodingChallenges/144-black-hole-visualization
Links discussed in this video:
🔗 STEM Coding Slides:
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide1.png
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide2.png
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide3.png
🔗 Simulating a Black Hole!: https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole.html
🔗 How to draw a Black Hole: http://rantonels.github.io/starless/
🔗 Astronomers Capture First Image of a Black Hole: https://eventhorizontelescope.org/
🔗 Image of a Spherical Black Hole with Thin Accretion Disk: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1979A&A....75..228L;
🎥 How to Understand the Image of a Black Hole by Veritasium: https://youtu.be/zUyH3XhpLTo
🎥 Slingshot with Gravity! by STEM Coding: https://youtu.be/RkpulcVKLRw
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📄 Code of Conduct: https://github.com/CodingTrain/Code-of-Conduct
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#blackhole #spacetime #simulation
- published: 26 Apr 2019
- views: 143284
Title: ""From Newtonian Gravity to Einstein's Theory of General Relativity"
Speaker: Andrew J. Tolley, PhD
Date: 10/20/2015
- published: 10 Dec 2015
- views: 22368
Text at http://howfarawayisit.com/documents/
Music free version https://www.youtube.com/playlist?list=PLpH1IDQEoE8RP8YVxyCQqvkQ0mjvM9rJq
In this segment of the “How Fast Is It” video book, we cover the effects of general relativity and how they differ from what Newton’s gravity predicts. Our first effect is the orbit of Mercury that precesses more than Newtonian gravity predicts. To understand the non-Euclidian space that Mercury orbits in, we introduce the Schwarzschild metric and compare it to the Minkowski metric for flat space-time. We illustrate the positive curvature around the Sun using concentric circles with shrinking circumferences. We then show how this slight difference in curvature produces additional movement in the precessing perihelion of Mercury’s orbit that exactly fits the measured number. Our next effect is the bending of light. We cover Arthur Eddington’s famous measurement during a total eclipse of the Sun and show how the amount of starlight bending matched Einstein’s calculations better than Newton’s. We extend this bending effect to show how Einstein Rings and gravitational lensing work. And we show how this effect tips over light cones and changes world-lines. Our third effect is gravitational time dilation. We show how it works and cover how our GPS uses it. We also cover the Pound-Rebka experiment used the Mossbauer Effect to showed how this time dilation impacts gravitational redshift. We also illustrate how this effect resolves the Twin Paradox we introduced in the Special Relativity segment. Our final implication involves frame-dragging. To understand this effect, we introduce the Kerr Metric that covers rotating energy densities that literally drag space along with them. We use Gravity Probe B to illustrate how it works and how it is measured. We finish with an in depth look at the black hole in the movie Interstellar.
- published: 13 Dec 2015
- views: 125964
Frontiers/Controversies in Astrophysics (ASTR 160)
Professor Bailyn introduces the course and discusses the course material and requirements. The three major topics that the course will cover are (1) exoplanets--planets around stars other than the Sun, (2) black holes--stars whose gravitational pull is so strong that even their own light rays cannot escape, and (3) cosmology--the study of the Universe as a whole. Class proper begins with a discussion on planetary orbits. A brief history of astronomy is also given and its major contributors over the centuries are introduced: Ptolemy, Galileo, Copernicus, Kepler, and Newton.
00:00 - Chapter 1. Introduction
05:38 - Chapter 2. Topics of the Course
12:57 - Chapter 3. Course Requirements
21:03 - Chapter 4. Planetary Orbits
31:32 - Chapter 5. From Newton's Laws of Motion to the Theory of Everything
38:10 - Chapter 6. The Newtonian Modification of Kepler's Third Law
Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses
This course was recorded in Spring 2007.
- published: 29 Sep 2008
- views: 214767
A basic introduction to Analytical Mechanics derived from Newtonian Mechanics, covering the Lagrangian, principle of least action, Euler Lagrange equation and Hamiltonian.
- published: 07 Jan 2013
- views: 93309
developed with YouTube
Dark Star
Dark Star or Darkstar may refer to:
Astronomy
James T. Struck BA, BS, AA, MLIS argued for Dark Stars as a type of star that generates no or insignicant light even with heat production. He argued for these new stars like purple stars (which were observed historically), green stars (which can be seen) and low energy stars.
Media and entertainment
Film
Literature
Comics
This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Dark_Star
Dark star (Newtonian mechanics)
A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light. Whether light is affected by gravity under Newtonian mechanics is questionable but if it were accelerated the same way as projectiles, any light emitted at the surface of a dark star would be trapped by the star's gravity, rendering it dark, hence the name.
Dark star history
John Michell and dark stars
During 1783 geologist John Michell wrote a letter to Henry Cavendish outlining the expected properties of dark stars, published by The Royal Society in their 1784 volume. Michell calculated that when the escape velocity at the surface of a star was equal to or greater than lightspeed, the generated light would be gravitationally trapped, so that the star would not be visible to a distant astronomer.
This assumes that light is influenced by gravity in the same way as massive objects.
Michell's idea for calculating the number of such "invisible" stars anticipated 20th century astronomers' work: he suggested that since a certain proportion of double-star systems might be expected to contain at least one "dark" star, we could search for and catalogue as many double-star systems as possible, and identify cases where only a single circling star was visible. This would then provide a statistical baseline for calculating the amount of other unseen stellar matter that might exist in addition to the visible stars.
This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Dark_star_(Newtonian_mechanics)
Dark star (dark matter)
A dark star is a type of star that may have existed early in the universe before conventional stars were able to form. The stars would be composed mostly of normal matter, like modern stars, but a high concentration of neutralino dark matter within them would generate heat via annihilation reactions between the dark-matter particles. This heat would prevent such stars from collapsing into the relatively compact sizes of modern stars and therefore prevent nuclear fusion among the normal matter atoms from being initiated.
Under this model, a dark star is predicted to be an enormous cloud of hydrogen and helium ranging between 4 and 2000 astronomical units in diameter and with a surface temperature low enough that the emitted radiation would be invisible to the naked eye.
In the unlikely event that dark stars have endured to the modern era, they could be detectable by their emissions of gamma rays, neutrinos, and antimatter and would be associated with clouds of cold molecular hydrogen gas that normally wouldn’t harbor such energetic particles.
This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Dark_star_(dark_matter)
Podcasts:
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[Wikipedia] Dark star (Newtonian mechanics)
A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light. Whether light is affected by gravity under Newtonian mechanics is unclear but if it were accelerated the same way as projectiles, any light emitted at the surface of a dark star would be trapped by the star's gravity, rendering it dark, hence the name. Dark stars are analogous to black holes in general relativity. https://en.wikipedia.org/wiki/Dark_star_(Newtonian_mechanics) Please support this channel and help me upload more videos. Become one of my Patreons at https://www.patreon.com/user?u=3823907
published: 14 Mar 2018 -
11 - Acceleration due to Gravity & Space-Time Continuum Curvature (General Relativity Vs. Newton)
Get more lessons like this at http://www.MathTutorDVD.com Learn about the acceleration due to the force of gravity in this lesson on gravitational acceleration. Here we explore why objects fall at the same rate in a gravity field. You will first learn that the acceleration due to gravity is the same for an object of any mass. Next, we explore the modern theories of physics to explain why an object experiencing a larger gravitational force should accelerate at the same rate as an object with less mass. We review Einstein's thought that inertial mass equals gravitational mass for any object. We further explore that in Einstein's Theory of General Relativity, objects simply follow straight paths through a curved space time continuum. The falling objects we see as the force of gravity ...
published: 15 Oct 2018 -
Neil deGrasse Tyson Explains Modified Newtonian Dynamics
A fan asks if Modified Newtonian Dynamics, a theory that attempts to explain the missing mass in the Universe without resorting to the existence of dark matter, is credible, or is it pseudoscience? To answer this Cosmic Query, Neil deGrasse Tyson explains MOND, as astrophysicists call it, to co-host Chuck Nice, touching on dark matter, dark gravity, and Newton’s Laws. But is it pseudoscience? No spoilers here: watch and learn for yourself. Support us on Patreon: https://www.patreon.com/startalkradio Subscribe to StarTalk: https://www.youtube.com/user/startalkradio?sub_confirmation=1 Follow StarTalk: Twitter: http://twitter.com/startalkradio Facebook: https://www.facebook.com/StarTalk Instagram: https://www.instagram.com/startalkradio/ About StarTalk: Science meets pop culture on StarT...
published: 22 Jan 2015 -
Modified Newtonian dynamics - Video Learning - WizScience.com
In physics, "modified Newtonian dynamics" is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies. Created in 1983 by Israeli physicist Mordehai Milgrom, the theory's original motivation was to explain the fact that the velocities of stars in galaxies were observed to be larger than expected based on Newtonian mechanics. Milgrom noted that this discrepancy could be resolved if the gravitational force experienced by a star in the outer regions of a galaxy was proportional to the square of its centripetal acceleration , or alternatively if gravitational force came to vary inversely with radius . In MOND, violation of Newton's Laws occurs at extremely small accelerations, characteristic of galaxies yet far below anything typically encounter...
published: 10 Sep 2015 -
2b) How about modifying Newtonian mechanics to explain the galactic rotation curves? "MOND"
An alternative to adding dark matter to galaxies to explain the rotation velocity that is way too fast is to change the long cherished Newtonian mechanics in the regime of small accelerations. Because the Modified Newtonian Dynamics (MOND) does not do very well for larger structures, and because there are systems that seem to need no modification of ordinary mechanics or that show a separation of the gravitation and the source, MOND is nowadays viewed less favorably than dark matter. But there is an important point that it gets right (by construction): it is as if the force law had one less power of r. Based on preprint DOI: 10.13140/RG.2.2.35022.41289 available at Research Gate. The research therein was partly funded by the spanish government under grant MINECO:FPA2016-75654-C2-1-P...
published: 01 Oct 2020 -
Coding Challenge #144: 2D Black Hole Visualization
Inspired by the recent image of the Powehi m87 black hole from the Event Horizon Telescope, I attempt to visualize the behavior or light (photons) following the path of spacetime around the black hole. 💻 Code: https://thecodingtrain.com/CodingChallenges/144-black-hole-visualization Links discussed in this video: 🔗 STEM Coding Slides: https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide1.png https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide2.png https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide3.png 🔗 Simulating a Black Hole!: https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole.html 🔗 How to draw a Black Hole: http://rantonels.github.io/starless/ 🔗 Astronomers Capture First Image of a Black Hole: h...
published: 26 Apr 2019 -
"From Newtonian Gravity to Einstein's Theory of General Relativity"
Title: ""From Newtonian Gravity to Einstein's Theory of General Relativity" Speaker: Andrew J. Tolley, PhD Date: 10/20/2015
published: 10 Dec 2015 -
How Fast Is It - 05 - General Relativity II - Effects (1080p)
Text at http://howfarawayisit.com/documents/ Music free version https://www.youtube.com/playlist?list=PLpH1IDQEoE8RP8YVxyCQqvkQ0mjvM9rJq In this segment of the “How Fast Is It” video book, we cover the effects of general relativity and how they differ from what Newton’s gravity predicts. Our first effect is the orbit of Mercury that precesses more than Newtonian gravity predicts. To understand the non-Euclidian space that Mercury orbits in, we introduce the Schwarzschild metric and compare it to the Minkowski metric for flat space-time. We illustrate the positive curvature around the Sun using concentric circles with shrinking circumferences. We then show how this slight difference in curvature produces additional movement in the precessing perihelion of Mercury’s orbit that exactly fit...
published: 13 Dec 2015 -
1. Introduction
Frontiers/Controversies in Astrophysics (ASTR 160) Professor Bailyn introduces the course and discusses the course material and requirements. The three major topics that the course will cover are (1) exoplanets--planets around stars other than the Sun, (2) black holes--stars whose gravitational pull is so strong that even their own light rays cannot escape, and (3) cosmology--the study of the Universe as a whole. Class proper begins with a discussion on planetary orbits. A brief history of astronomy is also given and its major contributors over the centuries are introduced: Ptolemy, Galileo, Copernicus, Kepler, and Newton. 00:00 - Chapter 1. Introduction 05:38 - Chapter 2. Topics of the Course 12:57 - Chapter 3. Course Requirements 21:03 - Chapter 4. Planetary Orbits 31:32 - Chap...
published: 29 Sep 2008 -
Analytical Mechanics
A basic introduction to Analytical Mechanics derived from Newtonian Mechanics, covering the Lagrangian, principle of least action, Euler Lagrange equation and Hamiltonian.
published: 07 Jan 2013
developed with YouTube
11:44
[Wikipedia] Dark star (Newtonian mechanics)
- Order: Reorder
- Duration: 11:44
- Uploaded Date: 14 Mar 2018
- views: 21
A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the sp...
A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light. Whether light is affected by gravity under Newtonian mechanics is unclear but if it were accelerated the same way as projectiles, any light emitted at the surface of a dark star would be trapped by the star's gravity, rendering it dark, hence the name. Dark stars are analogous to black holes in general relativity.
https://en.wikipedia.org/wiki/Dark_star_(Newtonian_mechanics)
Please support this channel and help me upload more videos. Become one of my Patreons at https://www.patreon.com/user?u=3823907
https://wn.com/Wikipedia_Dark_Star_(Newtonian_Mechanics)
A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light. Whether light is affected by gravity under Newtonian mechanics is unclear but if it were accelerated the same way as projectiles, any light emitted at the surface of a dark star would be trapped by the star's gravity, rendering it dark, hence the name. Dark stars are analogous to black holes in general relativity.
https://en.wikipedia.org/wiki/Dark_star_(Newtonian_mechanics)
Please support this channel and help me upload more videos. Become one of my Patreons at https://www.patreon.com/user?u=3823907
- published: 14 Mar 2018
- views: 21
54:35
11 - Acceleration due to Gravity & Space-Time Continuum Curvature (General Relativity Vs. Newton)
- Order: Reorder
- Duration: 54:35
- Uploaded Date: 15 Oct 2018
- views: 36050
Get more lessons like this at http://www.MathTutorDVD.com
Learn about the acceleration due to the force of gravity in this lesson on gravitational acceleration...
Get more lessons like this at http://www.MathTutorDVD.com
Learn about the acceleration due to the force of gravity in this lesson on gravitational acceleration. Here we explore why objects fall at the same rate in a gravity field. You will first learn that the acceleration due to gravity is the same for an object of any mass.
Next, we explore the modern theories of physics to explain why an object experiencing a larger gravitational force should accelerate at the same rate as an object with less mass. We review Einstein's thought that inertial mass equals gravitational mass for any object. We further explore that in Einstein's Theory of General Relativity, objects simply follow straight paths through a curved space time continuum.
The falling objects we see as the force of gravity is just a geometric effect of all objects trying to follow a straight path in a curved space.
https://wn.com/11_Acceleration_Due_To_Gravity_Space_Time_Continuum_Curvature_(General_Relativity_Vs._Newton)
Get more lessons like this at http://www.MathTutorDVD.com
Learn about the acceleration due to the force of gravity in this lesson on gravitational acceleration. Here we explore why objects fall at the same rate in a gravity field. You will first learn that the acceleration due to gravity is the same for an object of any mass.
Next, we explore the modern theories of physics to explain why an object experiencing a larger gravitational force should accelerate at the same rate as an object with less mass. We review Einstein's thought that inertial mass equals gravitational mass for any object. We further explore that in Einstein's Theory of General Relativity, objects simply follow straight paths through a curved space time continuum.
The falling objects we see as the force of gravity is just a geometric effect of all objects trying to follow a straight path in a curved space.
- published: 15 Oct 2018
- views: 36050
3:58
Neil deGrasse Tyson Explains Modified Newtonian Dynamics
- Order: Reorder
- Duration: 3:58
- Uploaded Date: 22 Jan 2015
- views: 33647
A fan asks if Modified Newtonian Dynamics, a theory that attempts to explain the missing mass in the Universe without resorting to the existence of dark matter,...
A fan asks if Modified Newtonian Dynamics, a theory that attempts to explain the missing mass in the Universe without resorting to the existence of dark matter, is credible, or is it pseudoscience? To answer this Cosmic Query, Neil deGrasse Tyson explains MOND, as astrophysicists call it, to co-host Chuck Nice, touching on dark matter, dark gravity, and Newton’s Laws. But is it pseudoscience? No spoilers here: watch and learn for yourself.
Support us on Patreon: https://www.patreon.com/startalkradio
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About StarTalk:
Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up!
#StarTalk #NeildeGrasseTyson
https://wn.com/Neil_Degrasse_Tyson_Explains_Modified_Newtonian_Dynamics
A fan asks if Modified Newtonian Dynamics, a theory that attempts to explain the missing mass in the Universe without resorting to the existence of dark matter, is credible, or is it pseudoscience? To answer this Cosmic Query, Neil deGrasse Tyson explains MOND, as astrophysicists call it, to co-host Chuck Nice, touching on dark matter, dark gravity, and Newton’s Laws. But is it pseudoscience? No spoilers here: watch and learn for yourself.
Support us on Patreon: https://www.patreon.com/startalkradio
Subscribe to StarTalk: https://www.youtube.com/user/startalkradio?sub_confirmation=1
Follow StarTalk:
Twitter: http://twitter.com/startalkradio
Facebook: https://www.facebook.com/StarTalk
Instagram: https://www.instagram.com/startalkradio/
About StarTalk:
Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up!
#StarTalk #NeildeGrasseTyson
- published: 22 Jan 2015
- views: 33647
3:10
Modified Newtonian dynamics - Video Learning - WizScience.com
- Order: Reorder
- Duration: 3:10
- Uploaded Date: 10 Sep 2015
- views: 1469
In physics, "modified Newtonian dynamics" is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies. Created in...
In physics, "modified Newtonian dynamics" is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies. Created in 1983 by Israeli physicist Mordehai Milgrom, the theory's original motivation was to explain the fact that the velocities of stars in galaxies were observed to be larger than expected based on Newtonian mechanics. Milgrom noted that this discrepancy could be resolved if the gravitational force experienced by a star in the outer regions of a galaxy was proportional to the square of its centripetal acceleration , or alternatively if gravitational force came to vary inversely with radius . In MOND, violation of Newton's Laws occurs at extremely small accelerations, characteristic of galaxies yet far below anything typically encountered in the Solar System or on Earth.
MOND is an example of a class of theories known as modified gravity, and is an alternative to the hypothesis that the dynamics of galaxies are determined by massive, invisible dark matter halos. Since Milgrom's original proposal, MOND has successfully predicted a variety of galactic phenomena that are difficult to understand from a dark matter perspective. However, MOND and its generalisations do not adequately account for observed properties of galaxy clusters, and no satisfactory cosmological model has been constructed from the theory.
Several independent observations point to the fact that the visible mass in galaxies and galaxy clusters is insufficient to account for their dynamics, when analysed using Newton's laws. This discrepancy – known as the "missing mass problem" – was first identified for clusters by Swiss astronomer Fritz Zwicky in 1933 , and subsequently extended to include spiral galaxies by the 1939 work of Horace Babcock on Andromeda. These early studies were augmented and brought to the attention of the astronomical community in the 1960s and 1970s by the work of Vera Rubin at the Carnegie Institute in Washington, who mapped in detail the rotation velocities of stars in a large sample of spirals. While Newton's Laws predict that stellar rotation velocities should decrease with distance from the galactic centre, Rubin and collaborators found instead that they remain almost constant – the rotation curves are said to be "flat". This observation necessitates at least one of the following: 1) There exists in galaxies large quantities of unseen matter which boosts the stars' velocities beyond what would be expected on the basis of the visible mass alone, or 2) Newton's Laws do not apply to galaxies. The former leads to the dark matter hypothesis; the latter leads to MOND.
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Background Music:
"The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library.
This video uses material/images from https://en.wikipedia.org/wiki/Modified+Newtonian+dynamics, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.
https://wn.com/Modified_Newtonian_Dynamics_Video_Learning_Wizscience.Com
In physics, "modified Newtonian dynamics" is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies. Created in 1983 by Israeli physicist Mordehai Milgrom, the theory's original motivation was to explain the fact that the velocities of stars in galaxies were observed to be larger than expected based on Newtonian mechanics. Milgrom noted that this discrepancy could be resolved if the gravitational force experienced by a star in the outer regions of a galaxy was proportional to the square of its centripetal acceleration , or alternatively if gravitational force came to vary inversely with radius . In MOND, violation of Newton's Laws occurs at extremely small accelerations, characteristic of galaxies yet far below anything typically encountered in the Solar System or on Earth.
MOND is an example of a class of theories known as modified gravity, and is an alternative to the hypothesis that the dynamics of galaxies are determined by massive, invisible dark matter halos. Since Milgrom's original proposal, MOND has successfully predicted a variety of galactic phenomena that are difficult to understand from a dark matter perspective. However, MOND and its generalisations do not adequately account for observed properties of galaxy clusters, and no satisfactory cosmological model has been constructed from the theory.
Several independent observations point to the fact that the visible mass in galaxies and galaxy clusters is insufficient to account for their dynamics, when analysed using Newton's laws. This discrepancy – known as the "missing mass problem" – was first identified for clusters by Swiss astronomer Fritz Zwicky in 1933 , and subsequently extended to include spiral galaxies by the 1939 work of Horace Babcock on Andromeda. These early studies were augmented and brought to the attention of the astronomical community in the 1960s and 1970s by the work of Vera Rubin at the Carnegie Institute in Washington, who mapped in detail the rotation velocities of stars in a large sample of spirals. While Newton's Laws predict that stellar rotation velocities should decrease with distance from the galactic centre, Rubin and collaborators found instead that they remain almost constant – the rotation curves are said to be "flat". This observation necessitates at least one of the following: 1) There exists in galaxies large quantities of unseen matter which boosts the stars' velocities beyond what would be expected on the basis of the visible mass alone, or 2) Newton's Laws do not apply to galaxies. The former leads to the dark matter hypothesis; the latter leads to MOND.
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Disclaimer: This video is for your information only. The author or publisher does not guarantee the accuracy of the content presented in this video. USE AT YOUR OWN RISK.
Background Music:
"The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library.
This video uses material/images from https://en.wikipedia.org/wiki/Modified+Newtonian+dynamics, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.
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Disclaimer: This video is for your information only. The author or publisher does not guarantee the accuracy of the content presented in this video. USE AT YOUR OWN RISK.
Background Music:
"The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library.
This video uses material/images from https://en.wikipedia.org/wiki/Modified+Newtonian+dynamics, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.
- published: 10 Sep 2015
- views: 1469
9:25
2b) How about modifying Newtonian mechanics to explain the galactic rotation curves? "MOND"
- Order: Reorder
- Duration: 9:25
- Uploaded Date: 01 Oct 2020
- views: 76
An alternative to adding dark matter to galaxies to explain the rotation velocity that is way too fast is to change the long cherished Newtonian mechanics in th...
An alternative to adding dark matter to galaxies to explain the rotation velocity that is way too fast is to change the long cherished Newtonian mechanics in the regime of small accelerations.
Because the Modified Newtonian Dynamics (MOND) does not do very well for larger structures, and because there are systems that seem to need no modification of ordinary mechanics or that show a separation of the gravitation and the source, MOND is nowadays viewed less favorably than dark matter. But there is an important point that it gets right (by construction): it is as if the force law had one less power of r.
Based on preprint DOI: 10.13140/RG.2.2.35022.41289
available at Research Gate.
The research therein was partly funded by the spanish government under grant MINECO:FPA2016-75654-C2-1-P (Spain); Univ. Complutense de Madrid under research group 910309 and the IPARCOS institute. The author declares that he has no conflict of interest. This video is part of a public dissemination effort and involves no profit.
https://wn.com/2B)_How_About_Modifying_Newtonian_Mechanics_To_Explain_The_Galactic_Rotation_Curves_Mond
An alternative to adding dark matter to galaxies to explain the rotation velocity that is way too fast is to change the long cherished Newtonian mechanics in the regime of small accelerations.
Because the Modified Newtonian Dynamics (MOND) does not do very well for larger structures, and because there are systems that seem to need no modification of ordinary mechanics or that show a separation of the gravitation and the source, MOND is nowadays viewed less favorably than dark matter. But there is an important point that it gets right (by construction): it is as if the force law had one less power of r.
Based on preprint DOI: 10.13140/RG.2.2.35022.41289
available at Research Gate.
The research therein was partly funded by the spanish government under grant MINECO:FPA2016-75654-C2-1-P (Spain); Univ. Complutense de Madrid under research group 910309 and the IPARCOS institute. The author declares that he has no conflict of interest. This video is part of a public dissemination effort and involves no profit.
- published: 01 Oct 2020
- views: 76
42:30
Coding Challenge #144: 2D Black Hole Visualization
- Order: Reorder
- Duration: 42:30
- Uploaded Date: 26 Apr 2019
- views: 143284
Inspired by the recent image of the Powehi m87 black hole from the Event Horizon Telescope, I attempt to visualize the behavior or light (photons) following the...
Inspired by the recent image of the Powehi m87 black hole from the Event Horizon Telescope, I attempt to visualize the behavior or light (photons) following the path of spacetime around the black hole.
💻 Code: https://thecodingtrain.com/CodingChallenges/144-black-hole-visualization
Links discussed in this video:
🔗 STEM Coding Slides:
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide1.png
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide2.png
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide3.png
🔗 Simulating a Black Hole!: https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole.html
🔗 How to draw a Black Hole: http://rantonels.github.io/starless/
🔗 Astronomers Capture First Image of a Black Hole: https://eventhorizontelescope.org/
🔗 Image of a Spherical Black Hole with Thin Accretion Disk: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1979A&A....75..228L;
🎥 How to Understand the Image of a Black Hole by Veritasium: https://youtu.be/zUyH3XhpLTo
🎥 Slingshot with Gravity! by STEM Coding: https://youtu.be/RkpulcVKLRw
🚂Website: https://thecodingtrain.com/
💡Github: https://github.com/CodingTrain
💖Membership: https://youtube.com/thecodingtrain/join
🛒Store: https://www.designbyhumans.com/shop/codingtrain/
📚Books: https://www.amazon.com/shop/thecodingtrain
🖋️Twitter: https://twitter.com/thecodingtrain
🎥Coding Challenges: https://www.youtube.com/playlist?list=PLRqwX-V7Uu6ZiZxtDDRCi6uhfTH4FilpH
🎥Intro to Programming using p5.js: https://www.youtube.com/playlist?list=PLRqwX-V7Uu6Zy51Q-x9tMWIv9cueOFTFA
📄 Code of Conduct: https://github.com/CodingTrain/Code-of-Conduct
🌐Help us caption and translate: http://www.youtube.com/timedtext_cs_panel?c=UCvjgXvBlbQiydffZU7m1_aw&tab;=2
🚩Suggest Topics: https://github.com/CodingTrain/Rainbow-Topics
👾Share your contribution: https://thecodingtrain.com/Guides/community-contribution-guide.html
🔗 p5.js: https://p5js.org
🔗 Processing: https://processing.org
#blackhole #spacetime #simulation
https://wn.com/Coding_Challenge_144_2D_Black_Hole_Visualization
Inspired by the recent image of the Powehi m87 black hole from the Event Horizon Telescope, I attempt to visualize the behavior or light (photons) following the path of spacetime around the black hole.
💻 Code: https://thecodingtrain.com/CodingChallenges/144-black-hole-visualization
Links discussed in this video:
🔗 STEM Coding Slides:
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide1.png
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide2.png
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide3.png
🔗 Simulating a Black Hole!: https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole.html
🔗 How to draw a Black Hole: http://rantonels.github.io/starless/
🔗 Astronomers Capture First Image of a Black Hole: https://eventhorizontelescope.org/
🔗 Image of a Spherical Black Hole with Thin Accretion Disk: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1979A&A....75..228L;
🎥 How to Understand the Image of a Black Hole by Veritasium: https://youtu.be/zUyH3XhpLTo
🎥 Slingshot with Gravity! by STEM Coding: https://youtu.be/RkpulcVKLRw
🚂Website: https://thecodingtrain.com/
💡Github: https://github.com/CodingTrain
💖Membership: https://youtube.com/thecodingtrain/join
🛒Store: https://www.designbyhumans.com/shop/codingtrain/
📚Books: https://www.amazon.com/shop/thecodingtrain
🖋️Twitter: https://twitter.com/thecodingtrain
🎥Coding Challenges: https://www.youtube.com/playlist?list=PLRqwX-V7Uu6ZiZxtDDRCi6uhfTH4FilpH
🎥Intro to Programming using p5.js: https://www.youtube.com/playlist?list=PLRqwX-V7Uu6Zy51Q-x9tMWIv9cueOFTFA
📄 Code of Conduct: https://github.com/CodingTrain/Code-of-Conduct
🌐Help us caption and translate: http://www.youtube.com/timedtext_cs_panel?c=UCvjgXvBlbQiydffZU7m1_aw&tab;=2
🚩Suggest Topics: https://github.com/CodingTrain/Rainbow-Topics
👾Share your contribution: https://thecodingtrain.com/Guides/community-contribution-guide.html
🔗 p5.js: https://p5js.org
🔗 Processing: https://processing.org
#blackhole #spacetime #simulation
- published: 26 Apr 2019
- views: 143284
52:01
"From Newtonian Gravity to Einstein's Theory of General Relativity"
- Order: Reorder
- Duration: 52:01
- Uploaded Date: 10 Dec 2015
- views: 22368
Title: ""From Newtonian Gravity to Einstein's Theory of General Relativity"
Speaker: Andrew J. Tolley, PhD
Date: 10/20/2015
Title: ""From Newtonian Gravity to Einstein's Theory of General Relativity"
Speaker: Andrew J. Tolley, PhD
Date: 10/20/2015
https://wn.com/From_Newtonian_Gravity_To_Einstein's_Theory_Of_General_Relativity
Title: ""From Newtonian Gravity to Einstein's Theory of General Relativity"
Speaker: Andrew J. Tolley, PhD
Date: 10/20/2015
- published: 10 Dec 2015
- views: 22368
29:33
How Fast Is It - 05 - General Relativity II - Effects (1080p)
- Order: Reorder
- Duration: 29:33
- Uploaded Date: 13 Dec 2015
- views: 125964
Text at http://howfarawayisit.com/documents/
Music free version https://www.youtube.com/playlist?list=PLpH1IDQEoE8RP8YVxyCQqvkQ0mjvM9rJq
In this segment of t...
Text at http://howfarawayisit.com/documents/
Music free version https://www.youtube.com/playlist?list=PLpH1IDQEoE8RP8YVxyCQqvkQ0mjvM9rJq
In this segment of the “How Fast Is It” video book, we cover the effects of general relativity and how they differ from what Newton’s gravity predicts. Our first effect is the orbit of Mercury that precesses more than Newtonian gravity predicts. To understand the non-Euclidian space that Mercury orbits in, we introduce the Schwarzschild metric and compare it to the Minkowski metric for flat space-time. We illustrate the positive curvature around the Sun using concentric circles with shrinking circumferences. We then show how this slight difference in curvature produces additional movement in the precessing perihelion of Mercury’s orbit that exactly fits the measured number. Our next effect is the bending of light. We cover Arthur Eddington’s famous measurement during a total eclipse of the Sun and show how the amount of starlight bending matched Einstein’s calculations better than Newton’s. We extend this bending effect to show how Einstein Rings and gravitational lensing work. And we show how this effect tips over light cones and changes world-lines. Our third effect is gravitational time dilation. We show how it works and cover how our GPS uses it. We also cover the Pound-Rebka experiment used the Mossbauer Effect to showed how this time dilation impacts gravitational redshift. We also illustrate how this effect resolves the Twin Paradox we introduced in the Special Relativity segment. Our final implication involves frame-dragging. To understand this effect, we introduce the Kerr Metric that covers rotating energy densities that literally drag space along with them. We use Gravity Probe B to illustrate how it works and how it is measured. We finish with an in depth look at the black hole in the movie Interstellar.
https://wn.com/How_Fast_Is_It_05_General_Relativity_Ii_Effects_(1080P)
Text at http://howfarawayisit.com/documents/
Music free version https://www.youtube.com/playlist?list=PLpH1IDQEoE8RP8YVxyCQqvkQ0mjvM9rJq
In this segment of the “How Fast Is It” video book, we cover the effects of general relativity and how they differ from what Newton’s gravity predicts. Our first effect is the orbit of Mercury that precesses more than Newtonian gravity predicts. To understand the non-Euclidian space that Mercury orbits in, we introduce the Schwarzschild metric and compare it to the Minkowski metric for flat space-time. We illustrate the positive curvature around the Sun using concentric circles with shrinking circumferences. We then show how this slight difference in curvature produces additional movement in the precessing perihelion of Mercury’s orbit that exactly fits the measured number. Our next effect is the bending of light. We cover Arthur Eddington’s famous measurement during a total eclipse of the Sun and show how the amount of starlight bending matched Einstein’s calculations better than Newton’s. We extend this bending effect to show how Einstein Rings and gravitational lensing work. And we show how this effect tips over light cones and changes world-lines. Our third effect is gravitational time dilation. We show how it works and cover how our GPS uses it. We also cover the Pound-Rebka experiment used the Mossbauer Effect to showed how this time dilation impacts gravitational redshift. We also illustrate how this effect resolves the Twin Paradox we introduced in the Special Relativity segment. Our final implication involves frame-dragging. To understand this effect, we introduce the Kerr Metric that covers rotating energy densities that literally drag space along with them. We use Gravity Probe B to illustrate how it works and how it is measured. We finish with an in depth look at the black hole in the movie Interstellar.
- published: 13 Dec 2015
- views: 125964
46:40
1. Introduction
- Order: Reorder
- Duration: 46:40
- Uploaded Date: 29 Sep 2008
- views: 214767
Frontiers/Controversies in Astrophysics (ASTR 160)
Professor Bailyn introduces the course and discusses the course material and requirements. The three major...
Frontiers/Controversies in Astrophysics (ASTR 160)
Professor Bailyn introduces the course and discusses the course material and requirements. The three major topics that the course will cover are (1) exoplanets--planets around stars other than the Sun, (2) black holes--stars whose gravitational pull is so strong that even their own light rays cannot escape, and (3) cosmology--the study of the Universe as a whole. Class proper begins with a discussion on planetary orbits. A brief history of astronomy is also given and its major contributors over the centuries are introduced: Ptolemy, Galileo, Copernicus, Kepler, and Newton.
00:00 - Chapter 1. Introduction
05:38 - Chapter 2. Topics of the Course
12:57 - Chapter 3. Course Requirements
21:03 - Chapter 4. Planetary Orbits
31:32 - Chapter 5. From Newton's Laws of Motion to the Theory of Everything
38:10 - Chapter 6. The Newtonian Modification of Kepler's Third Law
Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses
This course was recorded in Spring 2007.
https://wn.com/1._Introduction
Frontiers/Controversies in Astrophysics (ASTR 160)
Professor Bailyn introduces the course and discusses the course material and requirements. The three major topics that the course will cover are (1) exoplanets--planets around stars other than the Sun, (2) black holes--stars whose gravitational pull is so strong that even their own light rays cannot escape, and (3) cosmology--the study of the Universe as a whole. Class proper begins with a discussion on planetary orbits. A brief history of astronomy is also given and its major contributors over the centuries are introduced: Ptolemy, Galileo, Copernicus, Kepler, and Newton.
00:00 - Chapter 1. Introduction
05:38 - Chapter 2. Topics of the Course
12:57 - Chapter 3. Course Requirements
21:03 - Chapter 4. Planetary Orbits
31:32 - Chapter 5. From Newton's Laws of Motion to the Theory of Everything
38:10 - Chapter 6. The Newtonian Modification of Kepler's Third Law
Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses
This course was recorded in Spring 2007.
- published: 29 Sep 2008
- views: 214767
38:29
Analytical Mechanics
- Order: Reorder
- Duration: 38:29
- Uploaded Date: 07 Jan 2013
- views: 93309
A basic introduction to Analytical Mechanics derived from Newtonian Mechanics, covering the Lagrangian, principle of least action, Euler Lagrange equation and H...
A basic introduction to Analytical Mechanics derived from Newtonian Mechanics, covering the Lagrangian, principle of least action, Euler Lagrange equation and Hamiltonian.
https://wn.com/Analytical_Mechanics
A basic introduction to Analytical Mechanics derived from Newtonian Mechanics, covering the Lagrangian, principle of least action, Euler Lagrange equation and Hamiltonian.
- published: 07 Jan 2013
- views: 93309
11:44
[Wikipedia] Dark star (Newtonian mechanics)
A dark star is a theoretical object compatible with Newtonian mechanics that, due to its l...
published: 14 Mar 2018
[Wikipedia] Dark star (Newtonian mechanics)
[Wikipedia] Dark star (Newtonian mechanics)
- Report rights infringement
- published: 14 Mar 2018
- views: 21
A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light. Whether light is affected by gravity under Newtonian mechanics is unclear but if it were accelerated the same way as projectiles, any light emitted at the surface of a dark star would be trapped by the star's gravity, rendering it dark, hence the name. Dark stars are analogous to black holes in general relativity.
https://en.wikipedia.org/wiki/Dark_star_(Newtonian_mechanics)
Please support this channel and help me upload more videos. Become one of my Patreons at https://www.patreon.com/user?u=3823907
54:35
11 - Acceleration due to Gravity & Space-Time Continuum Curvature (General Relativity Vs. Newton)
Get more lessons like this at http://www.MathTutorDVD.com
Learn about the acceleration du...
published: 15 Oct 2018
11 - Acceleration due to Gravity & Space-Time Continuum Curvature (General Relativity Vs. Newton)
11 - Acceleration due to Gravity & Space-Time Continuum Curvature (General Relativity Vs. Newton)
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- published: 15 Oct 2018
- views: 36050
Get more lessons like this at http://www.MathTutorDVD.com
Learn about the acceleration due to the force of gravity in this lesson on gravitational acceleration. Here we explore why objects fall at the same rate in a gravity field. You will first learn that the acceleration due to gravity is the same for an object of any mass.
Next, we explore the modern theories of physics to explain why an object experiencing a larger gravitational force should accelerate at the same rate as an object with less mass. We review Einstein's thought that inertial mass equals gravitational mass for any object. We further explore that in Einstein's Theory of General Relativity, objects simply follow straight paths through a curved space time continuum.
The falling objects we see as the force of gravity is just a geometric effect of all objects trying to follow a straight path in a curved space.
3:58
Neil deGrasse Tyson Explains Modified Newtonian Dynamics
A fan asks if Modified Newtonian Dynamics, a theory that attempts to explain the missing m...
published: 22 Jan 2015
Neil deGrasse Tyson Explains Modified Newtonian Dynamics
Neil deGrasse Tyson Explains Modified Newtonian Dynamics
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- published: 22 Jan 2015
- views: 33647
A fan asks if Modified Newtonian Dynamics, a theory that attempts to explain the missing mass in the Universe without resorting to the existence of dark matter, is credible, or is it pseudoscience? To answer this Cosmic Query, Neil deGrasse Tyson explains MOND, as astrophysicists call it, to co-host Chuck Nice, touching on dark matter, dark gravity, and Newton’s Laws. But is it pseudoscience? No spoilers here: watch and learn for yourself.
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3:10
Modified Newtonian dynamics - Video Learning - WizScience.com
In physics, "modified Newtonian dynamics" is a theory that proposes a modification of Ne...
published: 10 Sep 2015
Modified Newtonian dynamics - Video Learning - WizScience.com
Modified Newtonian dynamics - Video Learning - WizScience.com
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- published: 10 Sep 2015
- views: 1469
In physics, "modified Newtonian dynamics" is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies. Created in 1983 by Israeli physicist Mordehai Milgrom, the theory's original motivation was to explain the fact that the velocities of stars in galaxies were observed to be larger than expected based on Newtonian mechanics. Milgrom noted that this discrepancy could be resolved if the gravitational force experienced by a star in the outer regions of a galaxy was proportional to the square of its centripetal acceleration , or alternatively if gravitational force came to vary inversely with radius . In MOND, violation of Newton's Laws occurs at extremely small accelerations, characteristic of galaxies yet far below anything typically encountered in the Solar System or on Earth.
MOND is an example of a class of theories known as modified gravity, and is an alternative to the hypothesis that the dynamics of galaxies are determined by massive, invisible dark matter halos. Since Milgrom's original proposal, MOND has successfully predicted a variety of galactic phenomena that are difficult to understand from a dark matter perspective. However, MOND and its generalisations do not adequately account for observed properties of galaxy clusters, and no satisfactory cosmological model has been constructed from the theory.
Several independent observations point to the fact that the visible mass in galaxies and galaxy clusters is insufficient to account for their dynamics, when analysed using Newton's laws. This discrepancy – known as the "missing mass problem" – was first identified for clusters by Swiss astronomer Fritz Zwicky in 1933 , and subsequently extended to include spiral galaxies by the 1939 work of Horace Babcock on Andromeda. These early studies were augmented and brought to the attention of the astronomical community in the 1960s and 1970s by the work of Vera Rubin at the Carnegie Institute in Washington, who mapped in detail the rotation velocities of stars in a large sample of spirals. While Newton's Laws predict that stellar rotation velocities should decrease with distance from the galactic centre, Rubin and collaborators found instead that they remain almost constant – the rotation curves are said to be "flat". This observation necessitates at least one of the following: 1) There exists in galaxies large quantities of unseen matter which boosts the stars' velocities beyond what would be expected on the basis of the visible mass alone, or 2) Newton's Laws do not apply to galaxies. The former leads to the dark matter hypothesis; the latter leads to MOND.
Wiz Science™ is "the" learning channel for children and all ages.
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Disclaimer: This video is for your information only. The author or publisher does not guarantee the accuracy of the content presented in this video. USE AT YOUR OWN RISK.
Background Music:
"The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library.
This video uses material/images from https://en.wikipedia.org/wiki/Modified+Newtonian+dynamics, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.
Wiz Science™ is "the" learning channel for children and all ages.
SUBSCRIBE TODAY
Disclaimer: This video is for your information only. The author or publisher does not guarantee the accuracy of the content presented in this video. USE AT YOUR OWN RISK.
Background Music:
"The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library.
This video uses material/images from https://en.wikipedia.org/wiki/Modified+Newtonian+dynamics, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.
9:25
2b) How about modifying Newtonian mechanics to explain the galactic rotation curves? "MOND"
An alternative to adding dark matter to galaxies to explain the rotation velocity that is ...
published: 01 Oct 2020
2b) How about modifying Newtonian mechanics to explain the galactic rotation curves? "MOND"
2b) How about modifying Newtonian mechanics to explain the galactic rotation curves? "MOND"
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- published: 01 Oct 2020
- views: 76
An alternative to adding dark matter to galaxies to explain the rotation velocity that is way too fast is to change the long cherished Newtonian mechanics in the regime of small accelerations.
Because the Modified Newtonian Dynamics (MOND) does not do very well for larger structures, and because there are systems that seem to need no modification of ordinary mechanics or that show a separation of the gravitation and the source, MOND is nowadays viewed less favorably than dark matter. But there is an important point that it gets right (by construction): it is as if the force law had one less power of r.
Based on preprint DOI: 10.13140/RG.2.2.35022.41289
available at Research Gate.
The research therein was partly funded by the spanish government under grant MINECO:FPA2016-75654-C2-1-P (Spain); Univ. Complutense de Madrid under research group 910309 and the IPARCOS institute. The author declares that he has no conflict of interest. This video is part of a public dissemination effort and involves no profit.
42:30
Coding Challenge #144: 2D Black Hole Visualization
Inspired by the recent image of the Powehi m87 black hole from the Event Horizon Telescope...
published: 26 Apr 2019
Coding Challenge #144: 2D Black Hole Visualization
Coding Challenge #144: 2D Black Hole Visualization
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- published: 26 Apr 2019
- views: 143284
Inspired by the recent image of the Powehi m87 black hole from the Event Horizon Telescope, I attempt to visualize the behavior or light (photons) following the path of spacetime around the black hole.
💻 Code: https://thecodingtrain.com/CodingChallenges/144-black-hole-visualization
Links discussed in this video:
🔗 STEM Coding Slides:
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide1.png
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide2.png
https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole_derivation_slide3.png
🔗 Simulating a Black Hole!: https://www.asc.ohio-state.edu/orban.14/stemcoding/blackhole.html
🔗 How to draw a Black Hole: http://rantonels.github.io/starless/
🔗 Astronomers Capture First Image of a Black Hole: https://eventhorizontelescope.org/
🔗 Image of a Spherical Black Hole with Thin Accretion Disk: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1979A&A....75..228L;
🎥 How to Understand the Image of a Black Hole by Veritasium: https://youtu.be/zUyH3XhpLTo
🎥 Slingshot with Gravity! by STEM Coding: https://youtu.be/RkpulcVKLRw
🚂Website: https://thecodingtrain.com/
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🎥Coding Challenges: https://www.youtube.com/playlist?list=PLRqwX-V7Uu6ZiZxtDDRCi6uhfTH4FilpH
🎥Intro to Programming using p5.js: https://www.youtube.com/playlist?list=PLRqwX-V7Uu6Zy51Q-x9tMWIv9cueOFTFA
📄 Code of Conduct: https://github.com/CodingTrain/Code-of-Conduct
🌐Help us caption and translate: http://www.youtube.com/timedtext_cs_panel?c=UCvjgXvBlbQiydffZU7m1_aw&tab;=2
🚩Suggest Topics: https://github.com/CodingTrain/Rainbow-Topics
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🔗 p5.js: https://p5js.org
🔗 Processing: https://processing.org
#blackhole #spacetime #simulation
52:01
"From Newtonian Gravity to Einstein's Theory of General Relativity"
Title: ""From Newtonian Gravity to Einstein's Theory of General Relativity"
Speaker: Andre...
published: 10 Dec 2015
"From Newtonian Gravity to Einstein's Theory of General Relativity"
"From Newtonian Gravity to Einstein's Theory of General Relativity"
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- published: 10 Dec 2015
- views: 22368
Title: ""From Newtonian Gravity to Einstein's Theory of General Relativity"
Speaker: Andrew J. Tolley, PhD
Date: 10/20/2015
29:33
How Fast Is It - 05 - General Relativity II - Effects (1080p)
Text at http://howfarawayisit.com/documents/
Music free version https://www.youtube.com/p...
published: 13 Dec 2015
How Fast Is It - 05 - General Relativity II - Effects (1080p)
How Fast Is It - 05 - General Relativity II - Effects (1080p)
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- published: 13 Dec 2015
- views: 125964
Text at http://howfarawayisit.com/documents/
Music free version https://www.youtube.com/playlist?list=PLpH1IDQEoE8RP8YVxyCQqvkQ0mjvM9rJq
In this segment of the “How Fast Is It” video book, we cover the effects of general relativity and how they differ from what Newton’s gravity predicts. Our first effect is the orbit of Mercury that precesses more than Newtonian gravity predicts. To understand the non-Euclidian space that Mercury orbits in, we introduce the Schwarzschild metric and compare it to the Minkowski metric for flat space-time. We illustrate the positive curvature around the Sun using concentric circles with shrinking circumferences. We then show how this slight difference in curvature produces additional movement in the precessing perihelion of Mercury’s orbit that exactly fits the measured number. Our next effect is the bending of light. We cover Arthur Eddington’s famous measurement during a total eclipse of the Sun and show how the amount of starlight bending matched Einstein’s calculations better than Newton’s. We extend this bending effect to show how Einstein Rings and gravitational lensing work. And we show how this effect tips over light cones and changes world-lines. Our third effect is gravitational time dilation. We show how it works and cover how our GPS uses it. We also cover the Pound-Rebka experiment used the Mossbauer Effect to showed how this time dilation impacts gravitational redshift. We also illustrate how this effect resolves the Twin Paradox we introduced in the Special Relativity segment. Our final implication involves frame-dragging. To understand this effect, we introduce the Kerr Metric that covers rotating energy densities that literally drag space along with them. We use Gravity Probe B to illustrate how it works and how it is measured. We finish with an in depth look at the black hole in the movie Interstellar.
46:40
1. Introduction
Frontiers/Controversies in Astrophysics (ASTR 160)
Professor Bailyn introduces the cour...
published: 29 Sep 2008
1. Introduction
1. Introduction
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- published: 29 Sep 2008
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Frontiers/Controversies in Astrophysics (ASTR 160)
Professor Bailyn introduces the course and discusses the course material and requirements. The three major topics that the course will cover are (1) exoplanets--planets around stars other than the Sun, (2) black holes--stars whose gravitational pull is so strong that even their own light rays cannot escape, and (3) cosmology--the study of the Universe as a whole. Class proper begins with a discussion on planetary orbits. A brief history of astronomy is also given and its major contributors over the centuries are introduced: Ptolemy, Galileo, Copernicus, Kepler, and Newton.
00:00 - Chapter 1. Introduction
05:38 - Chapter 2. Topics of the Course
12:57 - Chapter 3. Course Requirements
21:03 - Chapter 4. Planetary Orbits
31:32 - Chapter 5. From Newton's Laws of Motion to the Theory of Everything
38:10 - Chapter 6. The Newtonian Modification of Kepler's Third Law
Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses
This course was recorded in Spring 2007.
38:29
Analytical Mechanics
A basic introduction to Analytical Mechanics derived from Newtonian Mechanics, covering th...
published: 07 Jan 2013
Analytical Mechanics
Analytical Mechanics
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- published: 07 Jan 2013
- views: 93309
A basic introduction to Analytical Mechanics derived from Newtonian Mechanics, covering the Lagrangian, principle of least action, Euler Lagrange equation and Hamiltonian.
Dark Star
Dark Star or Darkstar may refer to:
Astronomy
James T. Struck BA, BS, AA, MLIS argued for Dark Stars as a type of star that generates no or insignicant light even with heat production. He argued for these new stars like purple stars (which were observed historically), green stars (which can be seen) and low energy stars.
Media and entertainment
Film
Literature
Comics
This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Dark_Star
![[Wikipedia] Dark star (Newtonian mechanics)](http://web.archive.org./web/20220309121813/https://i.ytimg.com/vi/SJPbCRVplTA/0.jpg)
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1. Introduction...
Analytical Mechanics...
Dark Star
I saw it all
All along
When I looked again
It was almost gone
Fragile sky
Seemed so strong
Was it destiny
That brought this on?
I can see your light fading
The night is contemplating
Will you shine on
Or is it too late?
Darkness casts a shadow brightly
I see the same inside me
Your reflection
Shows me my fate
Dark star
Fading faster
I feel your pain
Come closing in
'Cause what happens next
Will happen then
Scared to die
I won't pretend
More than anything
I'm afraid to meet your end
I can see your light fading
Dark star