Dust Definition and 172 Threads

Inside a dark room, when light comes through a hole, we see the dust particles as the particles scatter the light. But, when the whole window is open, we don't see the dust particles scattering the light. Why?

I want to open up a spectrometer to see how the inside looks like. Is it true that the CCD in spectrometer is more sensitive to dusts than normal camera CCD such that even a small speck of dust can cover the CCD pixels and the user will get holes in the spectrum? The following is example I found...

Why does dust stick to the fan blades just downstream of the rivet heads, forming a comet-tail like effect?

Hello. I went to my local astronomy club last night and the subject of diminished solar power caused by dust came up in conversation. We looked at images of the Insight mission and these showed a significant build up of said dust. This got me thinking. Could the solar panels of future Mars...

By "accumulation", I mean depth at the Earth's surface (i.e., whatever volume it is would be divided up the surface area). This dust would be from anything (e.g., meteors, stardust, etc.), but would only count stuff that ends up as dust (i.e., no gas or liquid). I guess a follow-on question...

Hi, If you have dirty window type airconditioner in a room and it hasn't been washed or cleaned for say 3 years since installed, can the dusts, molds, etc. inside the airconditioner got into your lungs and become sort of like streaky infiltrates? Or does it simply circulate the existing dusts...

What would happen if you tried to fly through obstacles using warp drive? Distorting space so that two points are closer wouldn't get around the fact that there might be obstacles (e.g. air molecules, space dust, empire destroyers) that you would bump into along the way right. Would all of that...

I have seen that interstellar dust contains the detritus of supernova explosions. But whet else does it contain? How uniform is it? Does its compositions vary significantly from place to place? This question started with wondering whether one could back out the origins of the Earth from it's...

Given the action ##S =-\sum m_q \int \sqrt{g_{\mu\nu}[x_q(\lambda)]\dot{x}^\mu_q(\lambda)\dot{x}^\nu_q(\lambda)} d\lambda## The Energy-Momentum Tensor (EMT) is defined by the variation of the metric $$\delta S = \frac{1}{2}\int T_{\mu\nu} \delta g^{\mu\nu} \sqrt{g} d^4x$$ Then I use two...

https://arxiv.org/abs/0805.3819 Approximating the Standard Model and gravity with dust on \mathbb{R}^{0|18} Robert N. C. Pfeifer [Submitted on 25 May 2008 (v1), last revised 11 Jul 2020 (this version, v14)] This article describes a single species of non-interacting massless dust on...

A few weeks ago I ordered a new 27" iMac with a 2TB SSD instead of the standard hybrid drive. Then the old Mac Pro died a few days before its replacement arrived. Broken heart, maybe? Now I've jumped ahead several versions of MacOS to 10.15 a.k.a. Catalina, and have to get new versions of all...

Is our home equipment and many other consumer's device usually designed to endure dust, debris, dirt or anything (even virus or bacteria) from the environment which is hard to avoid? What is the field of engineering or science that studies such issue?

The first way to solve this is to just say, by conservation of momentum, that M_{0}v_{0}=(M_{0}+Apx)\frac{v_0}{2} where Apx is the mass of dust the rocket comes into contact with in a distance x. For the second method, by considering the change of momentum of the dust in 1 second, we know the...

I've looked for a while and can't find an answer to this, hence the post. Ultimately this is a question about how the first pieces of "classical" matter formed from quantum matter. My study of self-organizing systems shows that you need a hierarchical build-up of structures to allow a complex...

The given solution is: However, I could not agree this solution, and my solotion is: So which one is correct? it seems a exponential decay would be more convincing. Thanks!

Recently, the origin of the cosmic microwave background as a relic radiation of the Big Bang was questioned and an idea of the CMB as thermal radiation of cosmic dust was revived and revisited. Under this theory, the temperature of the cosmic dust is predicted to be 2.776 K which differs from...

How does radiation from a star clear dust from a proto-planetary disc, changing the area from one of opaqueness to one of transparency? Please note that I am a retired engineer with an interest in astronomy, cosmology and particle physics but very much a layman..

We know interstellar space and intergalatic space is not empty. Couldn't small dust particles block the light of distant galaxys?

Is it possible to generate static electricity from air flow containing particles example smoke or dust flow, or does anyone know of experiments such as the kelvin water dropper converted to generate static from air flow ? Thanks

hey! EDIT: I didn’t post this in homework help because there aren’t any computational questions, it’s just conceptual My assignment scenario consists of a star (blackbody) surrounded by an expanding shell of hot gas. I’m given its spectrum and it is a continuous emission spectrum. Emission...

Hello, Assuming that dust is formed by silicates with Mg and Fe. What is the largest possible silicate dust-to-gas ratio in mass?

Any cooling fan, as well as any objects that it cools, will invariably become choked with fine dust after a time. But this seems quite surprising considering that all the dust is being accumulated on surfaces that are exposed to large currents of moving air. I've learned of two possible...

In dusty climates, do spiders (generally speaking) clean their webs of the dust? - or live with it? - or leave the old web and make a new one? In the southwestern USA, the ridges on exterior door molding and siding get covered with small dusty spider webs, each only a few inches long. It...

i'v googled the subject and it seems like a serious problem, e.g. the dust accumulating on the solar panels, there has even been a term coined 'cleaning event' for Mars winds, as if this is a matter of luck to get the solar panels cleaned. A small carbon-dioxide vent on the tip of the rover...

Interstellar dust prevents us from seeing most of the light of the Milky Way. Does anyone know how bright it would look if it had no dust at all? As it is, the Milky Way is impossible to see from cities and many suburbs, but how would the situation improve if there were no dust between the stars?

Homework Statement Using conservation of energy, show that the 4-velocity ##u^{\mu}## of dust satisfies: ##u^{\mu}\nabla_{\mu}u^{\nu} = f u^{\nu}## Explicitly identify ##f##, which is some function of ##u^{\mu}##, ##\rho## and their derivatives. And show that this equation becomes...

A carpenter was grinding the concrete in the wall and the room so full of dust. Then the TV channel box malfunctioned.. is it possible cement dusts can become conductor when they covered the circuit board?

Homework Statement In an inertial frame O calculate the components of the stress–energy tensors of the following systems: (a) A group of particles all moving with the same velocity ##v = \beta e_x##, as seen in O. Let the rest-mass density of these particles be ##\rho_0##, as measured in...

Homework Statement My textbook states: Since the number of particles of dust is conserved we also have the conservation equation $$\nabla_\mu (\rho u^\mu)=0$$ Where ##\rho=nm=N/(\mathrm{d}x \cdot \mathrm{d}y \cdot \mathrm{d}z) m## is the mass per infinitesimal volume and ## (u^\mu) ## is...

After talking to a coworker, I looked into the wikipedia article on "Gravity of Earth". I found that the Earth's gravity is not uniform, which makes sense (never thought about it). I have always wondered why satellites de-orbit over time. Someone told me that there is enough space dust to slow...

Homework Statement A spaceship of frontal area 25 m2 passes through a cloud of interstellar dust at a speed of 1.0x106 m/s. The density of dust is 2.0x10-18 kg/m3. If all the particles of dust that impact on the spaceship stick to it, find the average decelerating force that the impact of the...

I recently came across a paper where there was a term ''stochastic heating of very small grains". I went through some papers on this area but I am still confused about it. What is the vibrational temperature associated with very small grains? Does temperature has got a meaning if it's a highly...

Hello all, Could desertification exacerbate dust storms so much, and thereby destroy agriculture on earth? (due to the drop in temperature and sunlight) Also, under what kind of circumstances would desertification spread so much so that all plants on Earth would become extinct? If such a thing...

Recently I read a book about Mars, and it says that global sandstorm blows from southern hemisphere to northern hemisphere at perihelion. It's because the southern part is more heated at that position and the closer distance to sun gives it a high temperature, thus sublimating large amount CO2...

I keep reading the general opinion that the improvement is just not worth the risk if you attempt to clean the mirror on a Newtonian. Clearly, there must be a point at which it really is an important thing to do. I thought I would try a back of fag packet calculation and see where it took me...

Homework Statement A broken spaceship is located 10 km above the center of a large circular thin sheet of unknown dust. The sheet has a radius of 106km and a density of 7×1011kg/m2. The spaceship and the dust attract each other due to the gravitational force. a) Find the initial acceleration of...

If a large cloud of dust of constant ρ is moving with a given ##\vec v ## in some frame, then at any given time and position inside the cloud there should not be no net energy or i-momentum flow on any surface of constant ##x^i ## (i=1,2,3) because the particles coming in cancels those going out...

Hello all, Another very idiotic question (sorry for the idiotic questions today). From what I learned, a perfect gas obbey pV=nRT because the gas molecules collide against each other in an amazingly elastic way; that is, they may collide a trillion times but will still keep their total kinetic...

Hi, I haven't posted an Astronomy question before. I did see some Astronomy questions in this section so I posted it here. But if it's in the wrong place, for future reference, please let me know where it should be posted. 1) The first problem I need guidance on is the value I have obtained...

Two questions: 1. What tools and techniques are typically used to determine and plot spatial distributions of compounds--particularly organic ones--in interstellar dust? 2. Is it presently possible to determine distributions of compounds along arcs distant from the galactic center? If so, can...

Hello everyone, I am designing a ship for my sci fi story and I need input regarding the shield. I am trying to make my story as hard sci fi as I can get away with. The story takes place a few centuries from now and details the first expedition to Alpha Centuri. The ship will have a cruising...

A few photons (even 2?) are enough to decoherence a dust particle in space (position eigenstates chosen) . If further photons impinge on it.. Can the dust particle be re-prepared? I think yes because the quantum is never switched of. So that it mean whenever eigenstates were chosen via...

Curie temperature for magnetite is 858 C, for iron 1043 C. Duralumin melting point is about 630 C. Does this mean that if I take a small silicone mold, place a magnet underneath it, add ferromagnetic powder to the mold and then pour molten aluminum in, I will get the aluminum detail with...

The concept of environmental decoherence has been a perpetual thorn in my brain despite an embarrassing amount of time contemplating the idea. At this point, I'm not even sure if I understand what it is purported to resolve. In many ways, it seems to me to be primarily a theory about logical set...

Today's APOD http://apod.nasa.gov/apod/ap160125.html Shows this fascinating table. What a pity that is doesn't show isotopes. Strange are Ba, La, Ce which are shown as large star but not supernova. The article says that the origin of Cu is not well known. Fascinating. I'm curious about the...

In both quantum and general relativity theories we are used to provide results in the "limited" conditions to demonstrate a correspondence between new and old formalism. For instance deflection of light of a star due to Sun in GR is double the amount given in classical theory. Yet I have...

I was just watching the time-lapse footage of the Philae landing and was wondering: How does a comet acquire and keep a dust layer on it's surface? Can anyone say? It just seems a bit odd to me.

I'm looking at equipment that scans an image through a feeder... evidently dust build up could be a problem. Thinking of a piece of paper, that might attract dust, that could be run through it (I saw a vid of a piece of cleaning paper run through a system - I'm presuming it is 'dust...

If we had a solid object of 1 square meter surface area, its maximum rate of radiation would be that of a blackbody of the same surface area, correct? Now, if we had a cloud of ultrafine (<100nm) dust wherein the surface area of the *cloud* was 1 square meter, would it be similarly limited? Or...

I'm not sure where to post this, but I wanted to show this just because of the incredible nature of the phenomenon. It's just the dust from a slow running wet grindstone. I assume just vibration, but the more carefully you look the more unbelievable it becomes. As the grindstone ran, some of...