Newtonian physics and relativity
Summary
TLDRThis video explores the foundational concepts of Newtonian physics, including Newton's three laws of motion and the law of universal gravitation, which laid the groundwork for understanding motion and forces. It contrasts these with Einstein's theories of relativity, which introduced the idea that time and space are relative and could be affected by motion and gravity. The video highlights the differences between Newton's absolute concepts of space and time and the relativistic view where they are intertwined, leading to a deeper understanding of phenomena like gravity as a curvature of space-time. It also touches on the unresolved questions and the ongoing quest for a unified theory that reconciles quantum mechanics with general relativity.
Takeaways
- 🎉 **Newton's Birthday**: January 4th marks the birthday of Sir Isaac Newton, who introduced foundational laws of physics.
- 📚 **Newtonian Physics**: Newton's laws, including the three laws of motion and the law of universal gravitation, form the basis of classical mechanics.
- 🔄 **Inertia and Motion**: Newton's first law explains that an object will remain at rest or in uniform motion unless acted upon by an external force.
- ⚖️ **Force and Acceleration**: Newton's second law (F=ma) links force, mass, and acceleration, describing how forces affect the motion of objects.
- 🔄 **Action and Reaction**: The third law states that every action has an equal and opposite reaction, a fundamental principle in dynamics.
- 🌐 **Universal Gravitation**: Newton's law of universal gravitation describes the gravitational attraction between masses and the concept of gravity.
- 🌌 **Evolution of Physics**: Physics has evolved beyond Newtonian mechanics with the advent of theories like general relativity, which offer deeper insights into the universe.
- 🚀 **Special Relativity**: Einstein's special relativity, introduced in 1905, asserts that the laws of physics are the same in all inertial frames and that the speed of light is constant.
- 🌀 **General Relativity**: Einstein's 1915 theory of general relativity posits that gravity arises from the curvature of space-time by mass and energy.
- 🌠 **Orbits and Predictions**: General relativity provided a more accurate explanation for the orbit of Mercury, including the precession of its perihelion, which Newtonian mechanics could not fully account for.
Q & A
What significant contribution did Isaac Newton make to physics?
-Isaac Newton formulated Newtonian physics, which includes the three laws of motion and the law of universal gravitation, providing some of the earliest comprehensive descriptions of how objects move and how the physical world operates.
What is Newton's first law of motion, also known as the law of inertia?
-Newton's first law states that a body at rest or in motion will continue to remain at rest or in motion unless acted upon by an external force.
How is the force acting on an object described by Newton's second law?
-Newton's second law describes the force acting on an object as the product of its mass and acceleration, mathematically expressed as F = ma.
What does Newton's third law of motion entail?
-Newton's third law states that for every action, there is an equal and opposite reaction, meaning that forces between two bodies are equal in magnitude and opposite in direction.
What is the law of universal gravitation as described by Newton?
-The law of universal gravitation states that the force of gravity between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
What is an inertial frame of reference in the context of Newtonian physics?
-An inertial frame of reference is a frame where either there is no motion or the motion is at a constant velocity with no acceleration. Newtonian physics assumes that all observers in different inertial frames will see the same physical phenomena.
How did James Clerk Maxwell's equations of electromagnetism challenge the principles of Newtonian physics?
-Maxwell's equations of electromagnetism showed that the form of these equations changed depending on the observer's inertial frame of reference, which contradicted the absolute nature of space and time in Newtonian physics.
What was the significance of the Lorentz transformation in the development of physics?
-The Lorentz transformation demonstrated that time and length are not absolute but change depending on the observer's inertial frame, which was a departure from Newtonian physics and laid the groundwork for the theory of relativity.
What was the main postulate of Einstein's special relativity?
-Special relativity postulates that the laws of physics are the same in all inertial frames and that the speed of light in a vacuum is constant for all observers, regardless of the motion of the light source or observer.
How does Einstein's general relativity differ from Newtonian physics in explaining gravity?
-General relativity posits that gravity is not a force but rather a consequence of the motion of masses through curved space-time, caused by the presence of mass, which contrasts with Newtonian physics where gravity is viewed as a force acting at a distance.
What was one of the major predictions of general relativity that confirmed its validity?
-One of the major predictions of general relativity that confirmed its validity was the observation that the orbit of Mercury's perihelion precesses, which could not be fully explained by Newtonian physics but was accurately predicted by general relativity.
Outlines
📚 Newtonian Physics and Its Evolution
This paragraph introduces the historical significance of Isaac Newton's contributions to physics, specifically his laws that laid the foundation for understanding motion and gravity. Newton's laws of motion and the law of universal gravitation are explained, emphasizing their universality across inertial frames of reference. The paragraph also touches on the concept of inertial frames and how they relate to our perception of motion. It sets the stage for a discussion on the evolution of physics, leading to the theories of relativity.
🌌 From Newton to Einstein: The Shift in Understanding Gravity
The second paragraph delves into the transition from Newtonian physics to Einstein's theory of relativity. It highlights the discrepancies between the two theories, particularly in the context of high velocities and strong gravitational fields. The paragraph explains how Einstein's special relativity, which posits that the laws of physics are consistent across all inertial frames and that the speed of light is constant, challenged the absolute nature of space and time in Newtonian physics. It also introduces general relativity, which describes gravity as a curvature of space-time caused by mass. The paragraph concludes by discussing the implications of these theories on our understanding of celestial bodies, such as the orbit of Mercury, and acknowledges the ongoing quest to answer questions that even general relativity cannot yet fully explain.
Mindmap
Keywords
💡Newtonian Physics
💡Law of Inertia
💡Law of Universal Gravitation
💡Inertial Frame of Reference
💡Electromagnetism
💡Lorentz Transformation
💡Special Relativity
💡General Relativity
💡Spacetime
💡Singularity
Highlights
Isaac Newton's birthday on January 4th, 1643, marks the birth of Newtonian physics.
Newtonian physics introduced fundamental laws describing the motion of objects in the world around us.
Newton's First Law of Inertia states that a body will remain at rest or in motion unless acted upon by an external force.
Newton's Second Law defines force as the product of an object's mass and acceleration (F = ma).
The Third Law of Motion asserts that every action has an equal and opposite reaction.
Newton's Law of Universal Gravitation describes the gravitational force between two masses.
Newtonian mechanics assumes that all observers in different inertial frames will observe the same physical phenomena.
An inertial frame of reference is used to describe relative motion without acceleration.
James Clerk Maxwell's equations of electromagnetism showed that the form of equations can change depending on the observer's frame.
Henrik Lorentz's transformation allowed for the preservation of the form of Maxwell's equations across different inertial frames.
Lorentz transformation revealed that time and length are not absolute but change with the observer's frame of reference.
Einstein's Special Relativity, introduced in 1905, postulated that the laws of physics are absolute in all inertial frames and that the speed of light is constant.
General Relativity, proposed by Einstein in 1915, suggests that gravity is the result of motion in a curved space-time caused by mass.
Newtonian physics and relativity do not contradict but are applicable in different contexts, with relativity taking precedence at high velocities.
General Relativity provided explanations for phenomena like the orbit of Mercury, which Newtonian physics could not fully account for.
Both Newtonian physics and general relativity have limitations, such as the breakdown of known laws at singularities within black holes.
Transcripts
[Music]
subscribe to our youtube channel and
press the bell icon to get the latest
updates
january the 4th is isaac newton's
birthday
from the year 1643 and newton gave us
the gift of newtonian physics
which were some of the earliest laws
that described
how the world around us worked and how
objects around us
moved physics has of course evolved
since and today we have the wonderful
theory of general relativity from which
we're still
learning new things about our universe
in this video
let's take a very basic simplified look
at the laws newton put forth
where and why they don't apply how
relativity helps
solve some questions and where newton
and einstein
differed in their theories i'm sandhya
ramesh and this is pure science
in the 17th century newton came up with
a set of rules and equations
that describe the physical world around
us
we all know these if we've studied
newton's three laws of motion in school
the first law the law of inertia states
that a body at rest
or in motion will continue to remain at
rest or in motion
unless an external force acts upon it
the second law states that the force
acting on an object
is the product of its mass and
acceleration f is equal to m a
the third law is that for every action
there is an equal and opposite reaction
newton also gave us the famous law of
universal gravitation
the force of gravity between two objects
is directly proportional to the product
of their masses
and inversely proportional to the square
of distance between them
all these equations and laws are a part
of newtonian mechanics or
classical mechanics these laws and
equations
came with an important property which is
that
all observers no matter where they're
situated and whether they're moving
that is regardless of which inertial
frame
they are in they would see the same
things
around them happening in the same way
these laws were considered to be
universal
an inertial frame of reference is our
way of
understanding and describing relative
motion
say a person is walking in front of me
from left to right
i am stationary so the person appears to
move to me
and is of course in fact moving however
both of us are on the surface of the
earth and the earth
is revolving around the sun moving
through space
but for the purposes of this observation
we assume that the earth is stationary
so
earth is our inertial frame of reference
we've seen more examples in our school
textbooks
if a person traveling in a train throws
a ball
up and the ball falls down it will fall
straight down for the person inside the
train
but if i'm standing on a road and seeing
the train pass
by i would see the same ball taking a
path that is
parabolic for the person inside the
train
the train is the inertial frame of
reference and the ball
is moving relative to the train inertial
frames
are in inertia so either in motion with
the same velocity
or at rest they are not accelerating
then in the 19th century james clerk
maxwell came up with a set of equations
when he was studying electricity
magnetism and light
this was combined to form what we know
as electromagnetism today
but a funny thing about these equations
where that the form of these equations
changed depending
on the observer's inertial frame of
reference
then came along henrik lorenz in the
early 20th century
who with what we know as lauren's
transformation
which we're not going to go into was
able to show
that these equations could have their
form preserved
even when the inertial frame changes the
lorenz transformation
transformation of inertial frames was
different from the
standard transformation of inertial
frames that was being applied for
newtonian physics
in newtonian physics length and time
are constant they are absolute and don't
change
so an object of a certain length in one
frame
is of the same length in a different
frame as well
and this is the same with time it passes
the same way
in all frames of reference but
the lorentz transformation showed that
time and
length actually do change depending on
which frame of reference you're
in and this made who else but
einstein think he wanted to understand
if time and length
by length space were invariable
so he first came up with special
relativity in 1905.
this theory postulated that the laws of
physics are absolute in
all inertial frames of reference and
that the speed of light in vacuum is the
same for all observers
irrespective of whether the observer or
the source of light is in motion
but without going into too much details
here
einstein basically realized that gravity
changed everything
this was because gravity was basically
acceleration for earth we know the value
of
small g 9.8 meters per second square
which means that
any body that is falling towards the
surface of earth
is accelerating or increasing in speed
at the rate of 9.8 meters per second
every second the falling object would
experience the same force if it's inside
a vehicle
that is accelerating at this rate or at
one g
and when acceleration or gravity was
factored into these equations even basic
geometry changes
this led einstein to realize that
gravity was actually the result of
motion not just through space but also
through time
all of this is of course extreme
simplification of all the work that went
into it
but einstein then eventually put forth
his theory
of general relativity in 1915
with the premise that mass distorts and
bends
space-time causing it to curve and
gravity
is essentially the result of motion in
this curved space time
now where do newtonian physics and
relativity differ technically they don't
contradict each other but when energies
or velocities are approaching the speed
of light
relativity applies instead of newtonian
physics because of space-time curvature
in newtonian physics there is no
difference in space and time
no matter where you're located or how
fast you're moving
in fact theoretically you can travel as
fast as you want if you have
enough force relativity however states
that nothing can travel faster than the
speed of light
general relativity changed the field of
physics completely
it entirely transformed how we
understood the world around us
and the universe around us it offered
explanations for many lingering
questions
in physics and in astronomy such as
very famously the example of the orbit
of mercury with newton's laws
in a two body system such as the sun and
mercury
where one object is orbiting around
another
the orbit will be in the form of an
ellipse with
the bigger mass at one of the two focal
points
this is true we do know that pretty much
all orbits are
elliptical to varying degrees so it was
thought
that in this classical elliptical orbit
according to newtonian physics that
mercury was in
the perihelion or the closest point to
the sun in the orbit
was fixed with every orbit and the data
and observations
fit this theory determining the orbit of
mercury was one of the biggest
tests for general relativity but of
course
just like newtonian physics couldn't
answer everything that we observe
around us general relativity doesn't
either
black holes are predicted by general
relativity
and singularities where all known laws
of physics break down
are allowed in general relativity but
at the point of a singularity inside a
black hole
the laws of relativity also break down
similarly we have many other questions
from general relativity that are still
unanswered
which hopefully in the near or far
future
we are able to answer because time flows
in only one direction
関連動画をさらに表示
#AghamUnite: Relativity and the Big Bang
Teori Yang Membuat Kalian Berfikir Ulang Tentang Arti "JATUH" | TEORI RELATIVITAS UMUM EINSTEIN
General Relativity Explained simply & visually
Roger Penrose: "Time Has No Beginning And Big Bang Wrong"
Einstein's Revolution: Crash Course History of Science #32
Newtonian Gravity: Crash Course Physics #8
5.0 / 5 (0 votes)