What is Dust: Definition and 181 Discussions

Dust is made of fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian process), volcanic eruptions, and pollution. Dust in homes is composed of about 50% dead skin cells. The rest, and in offices, and other human environments is composed of small amounts of plant pollen, human hairs, animal fur, textile fibers, paper fibers, minerals from outdoor soil, burnt meteorite particles, and many other materials which may be found in the local environment.

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  1. Pushoam

    B Scattering of light by dust particles

    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?
  2. A

    Dust free area when working with spectrometer

    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...
  3. S

    I Dust sticking to fan blade downstream of rivet head

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

    Could cymatics keep Martian dust off solar panels?

    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...
  5. S

    I What is the average annual accumulation of cosmic dust on Earth?

    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...
  6. C

    Air conditioner dust getting into lungs?

    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...
  7. Jarvis323

    Moving through Air, Dust, and Solid Objects with Warp Drive

    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...
  8. C

    B The composition of interstellar dust

    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...
  9. G

    I Variation of Metric and the Energy-Momentum Tensor: Where Am I Going Wrong?

    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...
  10. Buzz Bloom

    I The source of the dust in Martian dust storms

    The article I first read which discusses this topic is: "IDing Mars' Dust" by Dale Keiger Johns Hopkins Magazine Volume 70, Number 4, Winter 2018 Page 20 The principle researchers are Assistant Professor Kevin Lewis of Earth and planetary sciences in the Krieger School, and postdoctoral fellow...
  11. M

    A A strange theory of everything: dust on [itex]\mathbb{R}^{0|18}[/itex]

    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...
  12. jtbell

    Did My Old Mac Pro Die of a Broken Heart Before Its Replacement Arrived?

    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...
  13. K

    Dirt, debris, dust, moisture and machines

    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?
  14. E

    Rocket moving through a cloud of dust, variable mass problem

    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...
  15. H

    I How did the initial dust particles form?

    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...
  16. Haorong Wu

    The speed of a spaceship flying through dust

    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!
  17. V

    A CMB as thermal radiation of cosmic dust?

    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...
  18. R

    A How Does Stellar Radiation Clear Dust from a Proto-Planetary Disc?

    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..
  19. Z

    B Interstellar Dust: What Blocks Light From Distant Galaxys?

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

    Electrostatics from particle laden air

    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
  21. starstruck_

    Spectrum of hot gas uniformly mixed with dust

    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...
  22. N

    A What is the dust-to-gas ratio in oxygen-poor galaxies?

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

    I Dust Accumulation on Fan Blades and Elsewhere

    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...
  24. S

    Do spiders clean dust from their webs?

    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...
  25. R

    Can a Carbon Dioxide Vent on a Mars Rover Solve Dust Buildup on Solar Panels?

    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...
  26. C

    I How Bright Would the Milky Way Look If It Had No Dust?

    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?
  27. W

    By energy conservation, show the 4-velocity of dust satisfies this....

    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...
  28. S

    B Can Cement Dust Cause Electrical Malfunctions?

    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?
  29. S

    Transforming Stress-Energy Tensors in Different Frames

    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...
  30. P

    Dust in special relativity - conservation of particle number

    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...
  31. R

    I What causes the deceleration of a satellite? Space dust?

    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...
  32. flamespirit919

    Decelerating Force of Dust on Spaceship - Conservation of Momentum

    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...
  33. S

    A What is stochastic heating of very small grains?

    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...
  34. M

    The impact of desertification and dust storms on agriculture

    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...
  35. Singlau

    B Mars' Global Sandstorm: Causes and Effects

    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...
  36. sophiecentaur

    Stargazing Dust on the Mirror: Is Cleaning Worth the Risk?

    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...
  37. Dusty912

    Broken Spaceship Accelerating towards circular sheet of dust

    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...
  38. E

    I Is the Energy Stress Tensor of Dust Always Zero Inside a Moving Cloud?

    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...
  39. F

    B Why a dust cloud does not obey pV=nRT?

    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...
  40. henrco

    Interaction of dust and starlight - extinction

    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...
  41. Prez Cannady

    I Detecting organic compounds in interstellar dust

    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...
  42. DHF

    Writing: Input Wanted Designing a space ship and with the dust shield

    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...
  43. J

    Can a dust particle be re-prepared with further photons?

    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...
  44. N

    Will ferromagnetic dust retain magnetism in molten aluminum?

    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...
  45. Feeble Wonk

    B Decoherence and the Dust Particle

    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...
  46. anorlunda

    The Mystery of Elements in the Sun's Primordial Dust Cloud

    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...
  47. V

    Breakdown of Correspondence Principle: Null Dust Case

    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...
  48. F

    Unraveling the Mystery of the Comet Dust Layer

    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.
  49. marcophys

    Create a dust attracting piece of paper

    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...
  50. K

    Radiative exchange in an ultrafine 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...