Space Definition and 1000 Threads

Hello everyone, I am trying to find level shifter/voltage translation solutions that are space-qualified (ideally radiation hardened, etc.) that can logic level translate from FPGA I/O at 1.5V to and ADC at 1.8V while supporting uni- or bi-directional I/O and OE capabilities . This is for high...

The Exodus thread got me thinking about swimming pools in a rotating space station. Assume two scenarios: two toroidal pools that circumscribe the station, one is continuous and one is divided into segments by barriers. (Sorry, typing on my phone is very arduous for these old thumbs, so I...

My understanding of why Mars lost its atmosphere was because it cooled down too much internally and that when this happened, the planet lost its magnetic field that helped protect it from solar winds (which then ended up stripping away the planets atmosphere). Is there anything that people could...

Are gravitational waves purely temporal? An object with no spatial velocity experiences gravity due to temporal velocity?

I have some questions linked to the following experimentation: In 1985, the space shuttle Challenger took on board a cesium atomic clock. The duration of the mission, around our Earth, was seven days and the parameters of the trajectory were as follows: speed equal to 7700 m/s and altitude h...

A station is orbiting a planet at a distance R1, a moon is orbiting the planet at distance R2 with the period T. The planet itself has a radius rp and a mass mp. We know that when an object adds its velocity at a point in the orbit, the height of the opposite orbit will increase. Determine the...

Hi, In the picture below, M is Milky Way Galaxy in red, both A's are Andromeda Galaxy in positions P1 and P2 , and W is some random galaxy. Milky Way Galaxy lie in one plane just like all the planets in solar system. In what configuration Andromeda Galaxy lies? Does it lie almost at the same...

Bridge : For k= 1,2,3 ,4 let $N_k$ be the event that North has at least k aces. Let $S_k, E_k, W_k$ be be the analogous events for South, East, West. Discuss the number x of aces in West's possession in the events a)$W_1', $ b) $N_2S_2,$ c) $N_1'S_1'E_1'$ d) $W_2- W_3$ e)$N_1S_1E_1W_1$ f)...

As we all know, light itself is the fastest thing in the universe, and the cosmic speed limit, basically. That said, it is said to go at 299,792,458 meters per second in a vacuum. That is pretty fast. However, I have a question I want to ask... Does light really go that fast in a vacuum? I ask...

As I understand it, photons are subject to the same time and space distortions under SR as anything else, which is why they don't perceive time or space, since they travel at the speed of light. To an outside observer, then, they should appear stationary, immobile at their moment of creation...

Am refreshing on Metric spaces been a while... Consider the axioms below; 1. ##d(x,y)≥0## ∀ ##x, y ∈ X## - distance between two points 2. ## d(x,y) =0## iff ##x=y##, ∀ ##x,y ∈ X## 3.##d(x,y)=d(y,x)## ∀##x, y ∈ X## - symmetry 3. ##d(x,y)≤d(x,z)+d(z,y)## ∀##x, y,z ∈ X## - triangle inequality...

Problem: Let ## (X,d) ## be a metric space, denote as ## B(c,r) = \{ x \in X : d(c,x) < r \} ## the open ball at radius ## r>0 ## around ## c \in X ##, denote as ## \bar{B}(c, r) = \{ x \in X : d(c,x) \leq r \} ## the closed ball and for all ## A \subset X ## we'll denote as ## cl(A) ## the...

Hi. I have watched some YouTube videos which suggest space (itself) is expanding. This sounds the same as the distance (itself) between moving objects is increasing. What's the difference? How can this even be proven in a laboratory? It doesn't sound as though it can be measured with a tape...

Why is the Webb placed at L2 (Lagrange point 2)? I read some articles that said it would be perpetually shaded being on the opposite side of the sun and moon, but that makes no sense when the Webb orbit is so huge? So why is it at L2?

I would like to know what will be the visibility from the portable telescope aboard the International Space Station. What could they potentially view, and what are (at least some of) the things they are known to have looked at? Presumably they use it *inside* the ISS and not outside, and are...

Q1a) - My current wrong answer is <-5.9e7, -3.3e8, -2.17e8> I used the Fnet = Gm1m2 / d^2 <unit vector> But i keep getting a dif answer each time Q2a) - I thought i could find net force and then divide it by the mass, and multiply it by the time interval. However I got the answer <-4.5, 4.5...

A space is infinite dimensional when its basis is infinite. But how can I ensure that the basis of the space of all sequences whose limit is zero is infinite? (After solving that, I would like to have a hint on this very similar problem which says: let V be a Linear space of all continuous...

Greetings, all. Please forgive my ignorance, but this is a question which has been on my mind for many years: What space does the universe occupy? To clarify what I mean: I'm in a building which is in the city of Hillsboro, which is the county of Washington, which is in the state of Oregon...

In Quantum Mechanics, how can you justify the use of distributions like the delta functional without introducing a rigged Hilbert space? I see that some texts do not make any reference to this subject.

I'm reading about the engineering of the James Webb and it surprised me that the temperature difference will be about 318 degrees from one side of the telescope compared to the other (85 C on one side and -233 on the other). I didn't expect space to be that hot about a million miles further...

(a) Knowing ##E##, we can use equation (2) to determine ##V##. However, since ##\vec E## represents the distribution of electric field in space i.e. a function of (x,y,z). For example, ##\vec E = x \hat i + y \hat j + z \hat k##. Here we do not know this function so how can we know ##V## at a...

We can formulate the spacetime in an observer/coordinate independent way, i.e. a particle becomes a worldline in the 4d space. Then relative to each observer, the worldline can be casted to a function in R^3. However, I haven't found any reference on formulating configuration space in a...

Consider a rocket with mass ##m## in space is going to move forward. In order to do so, it needs to eject mass backwards. Let the mass that is ejected has velocity ##u## relative to the rocket. What is the equation for the final velocity? It is said that after ##dt## second, the rocket will...

Maybe this is more general discussion, but I am excited / nervous about the upcoming launch of the JWST. https://jwst.nasa.gov/content/webbLaunch/countdown.html I can't wait to see the observations this endeavor will bring!

By definition of the vector potential we may write \nabla \times A =B at least in flat space. Does this relation hold in curved space? I am particularly interested if we can still write this in a spatially flat Friedmann-Robertson-Walker background with metric ds^2=dt^2-a^2(dx^2+dy^2+dz^2) and...

Hello all. I am studying stat mech from Pathria's book. It says a system is completely described by all positions and momenta of all the N particles. This maybe represented by a single point in 6N-D gamma space. So, each point is a (micro)state. Now if we restrict the system (N,V,E to E+ΔE)...

When the pulse is given at A, the box move to the right. When it is absorbed at B, the box stop.

I've always had difficulty grasping why the electric and magnetic fields are in phase in EM waves in a vacuum. Of course, Maxwell's Equations imply that is the case, but I had a hard time intuitively visualizing it. Then I found this short video on YouTube. I would appreciate your opinion...

if we assume each photon of light as a very very light piece of matter (by famous E = mc^2 and then: m = E / c^2) and sum up all photons that have been made from the creation time of a galaxy (also considering limitation of speed of light) and also photons that accidentally passing throw that...

When a Mars Simulation Goes Wrong https://www.theatlantic.com/science/archive/2018/06/mars-simulation-hi-seas-nasa-hawaii/553532/ The article came across my desk (computer screen). Human behavior is complicated. I'm more interested in the technical side of space travel, specifically the...

Hi, I don't know if it is the right place to ask for the following: I was thinking about the difference between the notion of spacetime as 4D Lorentzian manifold and the thermodynamic state space. To me the spacetime as manifold makes sense from an 'intrinsic' point of view (let me say all the...

Looking for the best material for a heat exchanger exposed to vacuum in a space ship. I've initially gone with radiator vanes that are a ceramic blend and typically operate at twenty-five hundred degrees, but then I started wondering if there is a better material...and now I'm here, hoping for...

Hey! :giggle: Give a probability space and events $A$, $B$ and $C$ such that $P [C \mid A]>P [C \mid A \cup B]$.So we want that $$\frac{P[C\cap A]}{P[A]}>\frac{P[C\cap (A\cup B)]}{P[A\cup B]}=\frac{P[(C\cap A)\cup (C\cap B)]}{P[A\cup B]}$$ But how can we find these events ? :unsure:

When moving around a circular spinning space station (doughnut shaped) Is there any difference in the direction one goes? Is the energy expenditure the same or different? Would one ever feel like one is climbing? My gut feeling says no, as the person walking has the angular momentum matching...

Hello everybody, I am currently in the middle of my PhD in mathematics. In the beginning of the program I was quite sure that I would stay in academia, however it is becoming more and more clear to me that I want to go into industry once I am finished. During the last weeks I have started to...

It's written in one book I've got on solid state physics the following: Can someone please explain how to get this number of 230 combinatorially? Thanks!

Apparently, one of the solar arrays on the Lucy spacecraft failed to fully deploy. https://scitechdaily.com/nasas-lucy-stable-in-cruise-mode-problematic-solar-array-is-75-to-95-deployed/ The fault may not be fatal. They may have enough solar power to complete the mission. At the same time...

Hi there, experts on three-D space! while thinking about (physical) space, I have come up with the following (geometry) question: Is it possible to define five points (A, B, C, D, E) in Euclidian space, so that all distances (AB, AC, AD, AE, BC, BD, BE, CD, CE, DE) can be expressed in rational...

On a long trip the photon goes, but it occupies a wavelength of space at any particular time. If the space between start and finish (inspection) is expanding all the way all the journey time, then most of the expansion has no effect on the photon. Like eg second tenth is section currently passed...

We know that ##v = \omega r## where ##r = R_{\text{E}} + h##. To compensate for the motion, the plane must fly along the equator at the same speed as the Earth but in the opposite direction, i.e. from east to west, so $$\vec{v} = -\vec{ v}_{\text{E}}$$ $$v_{\text{E}} = \omega_{\text{E}}...

Hello , what quantum fields exist in intergalactic space ? What math describes these fields ?

Hello! I am reading "Differential Geometry and Mathematical Physics" by Rudolph and Schmidt. And they have and example of manifold (projective space). I believe that there is a typo in the book, but perhaps I miss something deep. Definitions are the following $$\mathbb{K}^n_\ast=\{\mathbf{x}\in...

Hi, I found this problem in Munkres' topology book, and it seems to be contradictory: Let X be a metric space. (a) Suppose that for some ϵ>0, every ϵ-Ball in X has compact closure. Show that X is complete. (b) Suppose that for each x\in X there is an \epsilon>0 such as the ball B(x,\epsilon) has...

I want to develop a 2D random field and its change with time with constant velocity. My process: 1. Define a 2D grid [x, y] with n \times n points 2. Define 1D time axis [t] with n_t elements 3. Find the lagrangian distance between the points in space with the velocity in x and y ...

While learning about Special Relativity I learned that we use the Transformation matrix to alter the space .This matrix differs for Contravariant and Covariant vectors.Why does it happen?,Why one kind of matrix (Jacobian) for basis vectors and other kind(Inverse Jacobian) for gradient...

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AFAIK there is no cosmological principle formulated about space and time. If it would be formulated, it would more or less state that spacetime is an interconnected whole, and has no gaps, edges or boundaries. It doesn't need to state wether spacetime is finite or infinite, that is an open...

I'm watching this minutephysics video on Lorentz transformations (part starting from 2:13 and ending at 4:10). In my spacetime diagram, my worldline will be along the ##ct## axis and the worldline of an observer moving relative to me will be at some angle w.r.t. the ##y## axis. When we switch...

Before that, Lawrence Kraus stated "Empty space is a boiling, bubbling brew of virtual particles that pop in and out of existence in a time scale so short that you can't even measure them" . After reading https://www.physicsforums.com/insights/physics-virtual-particles/ especially this statement...

Guys I have Problems with this task The arrangement consists of a point charge Q at a distance (x0, y0,0) from the origin and two perfectly conductive surfaces in the (x, z) and (y, z) plane a) Mathematical description of the space charge density p of the original and mirror charge using the...