Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework.
Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the Timaeus of Plato, or Socrates in his reflections on what the Greeks called khôra (i.e. "space"), or in the Physics of Aristotle (Book IV, Delta) in the definition of topos (i.e. place), or in the later "geometrical conception of place" as "space qua extension" in the Discourse on Place (Qawl fi al-Makan) of the 11th-century Arab polymath Alhazen. Many of these classical philosophical questions were discussed in the Renaissance and then reformulated in the 17th century, particularly during the early development of classical mechanics. In Isaac Newton's view, space was absolute—in the sense that it existed permanently and independently of whether there was any matter in the space. Other natural philosophers, notably Gottfried Leibniz, thought instead that space was in fact a collection of relations between objects, given by their distance and direction from one another. In the 18th century, the philosopher and theologian George Berkeley attempted to refute the "visibility of spatial depth" in his Essay Towards a New Theory of Vision. Later, the metaphysician Immanuel Kant said that the concepts of space and time are not empirical ones derived from experiences of the outside world—they are elements of an already given systematic framework that humans possess and use to structure all experiences. Kant referred to the experience of "space" in his Critique of Pure Reason as being a subjective "pure a priori form of intuition".
In the 19th and 20th centuries mathematicians began to examine geometries that are non-Euclidean, in which space is conceived as curved, rather than flat. According to Albert Einstein's theory of general relativity, space around gravitational fields deviates from Euclidean space. Experimental tests of general relativity have confirmed that non-Euclidean geometries provide a better model for the shape of space.
Dark side of the moon!
I can understand that Selena Gomez
I've been down the darkest alleys
Saw the dark side of the moon
in Wolf
or Transformer movie use that phrase,
But this is US Space Force, of all people!
US Space Force
Can the expansion/creation of space in the universe affect the speed of light over long distances? (dividing the space traveled (including expanded space) by the travel time). If the Hubble constant is valid throughout the universe, it follows that from a certain Megaparsec of distance, galaxies...
I assume that a space station like portrayed in 2001 A Space Odyssey could either be fixed in rotation, or contra-rotating. Is there an advantage of one over the other?
Hi everyone! I love science, am constantly interested in news in various fields, and have even done my own amateur research in physics and psychology, but I am an artist. And that’s why I most like to popularize scientific and technological progress, as well as highlight related issues through...
Hi
Someone told me that to hit the target, they just shoot the ICBM up the space in the right latitude, then wait for the earth to rotate until the target is right below the ICBM, then just drop down to hit the target.
That sounded strange, but seems doable. But I would think it's a lot faster...
How can space expand when space is not a physical thing? I’ve heard some say that is not expanding but rather it is getting less dense, which to me implies the same thing.
Space must have properties, it's not just empty nothing, and one of those properties is distance. When an object moves through space at a velocity V information has to be transferred between the object and space. The object has the information that it is moving at velocity V which is...
I wanna be checking homogeneity of space(only interested in vertical) for simplicity and example we can do is "ball is dropped". To check homogeneity, we use either passive or active transformation and I'm interested in lagrangians.
I heard that we can write lagrangians such as: ##L =...
Here is the definition of spacetime?
“In physics, spacetime is any mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum.”
But if space is literally the absence of matter or physical properties, and time has no...
Imagine experiment is such as I drop a ball from some height vertically only.
What’s the right way to do 2nd experiment in order to check homogeneity of space.
Way 1: I move a little bit and drop the ball (same height, it’s just I moved - ball as well, but not in terms of height)
Way 2: We...
As background, I grew up in a working class neighborhood where few parents went to school. In 1962, John Glenn came back from space. I was told this. I am not sure what the adults believed back them. "Space" was new. It would be 4 years before star trek, and even then,Space was labeled the...
Movement isn't required to achieve gravity, even the artificial kind. Standing on a rotating body requires you to be actually physically standing on it. How is this achieved? Well, by gravity of course. Unless you are tied/stuck to the rotating body, but in that case there is no gravity pushing...
From: https://www.physicsforums.com/posts/6925227
Can I stop space and enter from toggling my checkbutton?
My brain intially parsed that as:
Can I stop Space and (then) enter (it) by toggling my checkbutton?" 🤪🤪
I don't believe this question will interest anyone else, but remains worthy of notice because the solution is a formula that depends on the 36th root of a number.
You unexpectedly find yourself in a space with four Euclidean dimensions. Fortunately your molecules have been rearrange into a four...
To kickstart the discussion, I am thrilled to share with you the first idea: NASA's Shapeshifting Mars Rover Wheels, which can adapt their shape to navigate various terrains on the Red Planet
Can anyone tell me if this would be correct? Would Earth not be seen flashing from space like a lighthouse to a distant planet when it reflects oceans and then DMS as the sons reflection per perspective travels across land then back to Ocean then back to land?
I'm sure it probably says that...
I have no expertise in this area, other than rudimentary concepts. The following might apply if the visualization of space, as depicted below, represents actual reality, but I don't know for sure. Please help me understand better, you guys!
2-dimensional space
The curvatures deform into the...
I encounter a function that I don‘t know in the calculation of Relativistically invariant 2-body phase space integral:
in this equation, ##s##is the square of total energy of the system in the center-of-mass frame(I think)
I don't know what the function ##\lambda^{\frac{1}{2}}## is.
There are...
Saturn reclaims 'moon king' title with 62 newfound satellites, bringing total to 145
https://www.space.com/saturn-moon-king-62-newfound-satellites
Astronomers have discovered 62 new moons orbiting the ringed planet Saturn, bringing to total to 145 Moons, with 121 irregular moons and 24 regular...
I got this watch nearly a year ago and love it. It is a celebration of the Apollo 11 moon landing. The planets orbit to tell you the time. The stars and planets glow in the dark as well!
Hi again,
I've found interesting video.
Roller homopolar motor :
Roller Motor
Do you think the motor from 1:08 min Will self rotate in Vacuum/Space
(No other forces : Gravitational or Other type.)
Thank you in advance.
For this problem,
,
The four points are,
##P(8,2,6)##
##R(-2,16,-2)##
##Q(3.9,2)##
##S(\frac{14}{3}, \frac{20}{3}, \frac{10}{3})##
And the solution is,
However, does someone please know what in the proportion 2:1:3 mean?
Many thanks!
Do the people on this forum support manned (staffed) space exploration? I would like to know? Or would we be better off with simply robots exploring space for us. What is your opinion?
From NASA:
https://www.nasa.gov/feature/goddard/2023/hubble-sees-possible-runaway-black-hole-creating-a-trail-of-stars
"We think we're seeing a wake behind the black hole where the gas cools and is able to form stars. So, we're looking at star formation trailing the black hole," said Pieter...
Awhile back there was a discussion about the following scenario: an astronaut sets free into space outside his window a round magnet so it just sits there a distance away ensuring the spaceship has no effect on the experiment. Then he wafts out gently a large pail of tiny iron filings and dust...
According to Maxwell’s Equations, the speed an EM plane wave in free space, far from its source, is determined by the electric constant, ε0, and the magnetic constant, μ0, such that c = 1/√( ε0 μ0).
The units of ε0 are capacitance per unit length and the units of μ0 are inductance per unit...
As in title:
Plugging in the definition is straight forward, I am too lazy to type, I will just quote the book Fetter 1971:
Up to here everything is very straight forward, in particular, since we are working on free electron gas, ##E=\hbar \omega##
However, I have no idea how to arrive...
(Not sure about the prefix. Choose intermediate to be sure.)
This article Physicists Recreate Classic 'Double-Slit' Experiment Using Time Instead of Space has it's basis in this paper:
Double-slit time diffraction at optical frequencies
It certainly sounds intriguing but is there actually...
Many explanations out there for gravity. One that I saw a few months ago explained that our gravity hete on earth is space moving toward the center of the earth, and we should be falling to the center of earth at a rate of 9.8 m/ s/s. But the surface of the earth is in the way...
What happens to...
Hello,
I am solid on the following concepts but less certain on the correct understanding of what a random variable is...
Random Experiment: an experiment that has an uncertain outcome.
Trials: how many times we sequentially repeat a random experiment.
Sample space ##S##: the set of ALL...
In the book "Group theory and it's Applications to the Quantum Mechanics of atomic spectra " by Eugene P. Wigner
in chapter 4 The elements of quantum mechanics it is written
What does the wave-packet and the refractive index implies here.How to interpret this?
Dear Everybody,
I am having trouble with last part of this question.
I believe the answer is no. But I have to proof the general case. Here is my work for the problem:
Suppose that we have two distinct norms on the same vector space ##X## over complex numbers. Then there exists no ##K## in...
Dear everybody,
I am having some trouble proving the implication (or the forward direction.) Here is my work:
Suppose that we have an arbitrary linear functional ##l## on a Banach Space ##B## is continuous. Since ##l## is continuous linear functional on B, in other words, we want show that...
Hello :),
I am wondering of the right and direct method to calculate the following tangent spaces at ##1##: ##T_ISL_n(R)##, ##T_IU(n)## and ##T_ISU(n)##.
Definitions I know:
Given a smooth curve ##γ : (− ,) → R^n## with ##γ(0) = x##, a tangent vector ##˙γ(0)## is a vector with components...
How long does it take water ice H20 in space in our solar system to sublimate, say a basic ice cube? It starts as a solid cube at the temperature of whatever space is above Earth and then completely turns to vapor. Just looking for ballpark situation here.
Does anyone know of a table or place...
TL;DR Summary: Solar sytem forces on Unity
Hello !
For my last year in my school, I've got a project to do, and I wanted to recreate the Solar system with forces on Unity. My forces are Velocity and Acceleration (I'm using the Frenet's formulas).
I'm sorry I'm not a physicist and that's why...
I understand people collapse multi dimensional functions to make simpler visualisations, eg if you have a 500 dimension objective function in machine learning you can collapse it to 2D or 3D to get a visual idea of the objective-space.is this why Einstein did it as well? to make simpler...
Homework Statement:: Model for Gravity
Relevant Equations:: Rg -Rg = G/(8pi*c^4)T
The rubber table model for gravity can't quite translate to reality. One sees that a ball placed on the table distorts it, but this is due to it being in a uniform gravity field. Just what mechanism distorts...
I the lambda-CDM model, is the expansion of spacetime uniform around all of spacetime, is there a smooth transition between expanding parts of spacetime (the voids) and non-expanding parts of spacetime, or is there a sharp distinction between expanding and non-expanding parts of spacetime.
Is...
I am following [this YouTube lecture by Schuller][1] where he finds the appropriate formalism for the quantum mechanics in the physical curved space.
Everything makes sense to me but at the very end I see that we find the pull backed connection one-form on the base manifold.
He says to the end...
Can someone please explain to me how can we obtain this integral in eq. 5.27 from eq. 5.26? I quite do not understand how is it possible to make this adjustment and why the (p_(f))^2 appeared there in the numerator and also why a solid angle appeared there suddenly.
First of all, all the physical quantities presented in this topic are unknown variables, and I require a functional relationship between these unknown variables.
In a vast space that does not consider gravity , there are many ideal rigid balls moving freely. And in equilibrium. The ball is...
Can we say,
(y + z ) x1 = (y1 + z1) x is also an equation of a straight line in 3 dimensional space,
where (x1,y1,z1) and (x,y,z) are the coordinates of a given point and a variable point respectively on a 3D line that passes through the origin,
have seen equation of a straight line in 3...
Since space is expanding, and that expansion moves things, then those moved things must be moved by something. If moved by space itself, then space must be providing the energy. And if gravity is a function of space and time interacting, then what is the energy or mass of a volume of space...
Hi,
I am currently preparing for my exam and have just watched a video about motion in phase space.
From minute 4 a quadratic potential is introduced and then from minute 6 minute the phase trajectory.
Here are the pictures
quadratic potential
phase trajectory
Regarding phase...
First I found work:
W=(3.85x10^5)(2.45x10^8)
W= 9.43x10^13
Then used that for difference of kinetic energy:
9.43x10^13 = (1/2) (4.55x10^4)v2^2 - (1/2)(4.55x10^4)(1.22x10^4)^2
9.43x10^13 = (22750)v2^2 - 3.386x10^12
9.43x10^13 + 3.386x10^12 = (22750)v2^2
9.77x10^13 = 22750v2^2
9.77x10^13/22750...
Trying to make sense of small and large extra dimension(s) of phyiscal space in a simple intuitive example.
Consider a two dimensional manifold like R2 and we are trying to add a small and a large extra dimension.
Do we mean by smale extra dimension in this case something like (0,1)×R (the...
I'm reading the Feynman lectures chapter on "Curved Space", section 6-2. Say we're trying to figure out a way to measure average curvature on Earth. We know that 3d space is curved if Euclidean geometry rules don't work - e.g. the ratio of circumference and radius of a circle isn't ##2\pi##, or...