In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles, and in everyday as well as scientific usage, "matter" generally includes atoms and anything made up of them, and any particles (or combination of particles) that act as if they have both rest mass and volume. However it does not include massless particles such as photons, or other energy phenomena or waves such as light. Matter exists in various states (also known as phases). These include classical everyday phases such as solid, liquid, and gas – for example water exists as ice, liquid water, and gaseous steam – but other states are possible, including plasma, Bose–Einstein condensates, fermionic condensates, and quark–gluon plasma.Usually atoms can be imagined as a nucleus of protons and neutrons, and a surrounding "cloud" of orbiting electrons which "take up space". However this is only somewhat correct, because subatomic particles and their properties are governed by their quantum nature, which means they do not act as everyday objects appear to act – they can act like waves as well as particles and they do not have well-defined sizes or positions. In the Standard Model of particle physics, matter is not a fundamental concept because the elementary constituents of atoms are quantum entities which do not have an inherent "size" or "volume" in any everyday sense of the word. Due to the exclusion principle and other fundamental interactions, some "point particles" known as fermions (quarks, leptons), and many composites and atoms, are effectively forced to keep a distance from other particles under everyday conditions; this creates the property of matter which appears to us as matter taking up space.
For much of the history of the natural sciences people have contemplated the exact nature of matter. The idea that matter was built of discrete building blocks, the so-called particulate theory of matter, independently appeared in ancient Greece and ancient India among Buddhists, Hindus and Jains in 1st-millennium BC. Ancient philosophers who proposed the particulate theory of matter include Kanada (c. 6th–century BC or after), Leucippus (~490 BC) and Democritus (~470–380 BC).
Here is the Physical Review article:
"Supernovae sparked by dark matter in white dwarfs"
"A ball of asymmetric dark matter accumulated inside a white dwarf and collapsing under its own weight sheds enough gravitational potential energy through scattering with nuclei to spark the fusion...
Is it correct that dimensions more than the three (4th being time) that we perceive can be mathematically modeled but as yet remain unobserved?
If so, is it possible that dark matter/energy are "elements" which exist in those higher dimensions, and as such remain invisible to those constrained...
I can't understand how dark matter can form structures from the initial near uniform distribution as shown in simulation like those of the Eagle project http://icc.dur.ac.uk/Eagle/index.php. I understand how the initial density fluctuation are amplified and dark (and ordinary) matter start to...
Hello,
I have a general understanding of how we are aware of the presence of dark matter in the universe and the fact that we still don't know exactly what is that dark matter is made of.
I would like to know which instruments are used to try and find an answer. For instance, from what I...
Dark matter passes through everything, but is only influenced by gravity, so in the case of a neutron star, since dark matter doesn't interfere with ordinary matter, it can just pass through it, but neutrinos might be stopped by it's density, as neutrinos can just pass through stars almost as if...
When people graduate and have their degrees in engineering or physics or mathematics or what they may have done, some of these people will use some mathematics, very often which is some-what complicated (or not) arithmetic. Why will some people choose to strictly avoid using variables in the...
How long would it take for an object, stationary with respect to a black hole (mass of the sun), to fall from 1 AU into it beyond its event horizon?
From our frame of reference can we observe over time, a black hole growing in size as matter falls beyond the event horizon?
From our frame of...
I'm presuming some antiquarian noticed that there tends to be loads of tiny mass objects in the universe than huge mass objects. I'm presuming someone somewhere put their name to a trend about this distribution of matter. However, I'm struggling to find a name for it - if there is one. Can...
The URL below is from Rensselaer Alumni Magazine. It is about an unexpected observation of an xenon atom decay using the equipment designed for detecting dark matter particle interactions with xenon.
https://magazine.rpi.edu/at-rensselaer/dark-matter-detector-observes-rarest-event-ever-recorded
It seems that QED treats the matter and EM fields as independent yet coupled fields. On the other hand the EM field equations emerge immediately under local change of the phase of the matter field, exactly as required to reestablish local (gauge) invariance. From that perspective it almost seems...
Are there any research about Dark Matter missing some Hilbert space bases or observable?
Are bases or observables like spin, momentum, energy, position the basic quantum ingredients of any matter, what is the apriori explanation?
For Elastic neutron interactions with matter, they mentioned that the neutron will collide with atomic nucleus and the recoil nuclei quickly become ion pairs and loose energy through excitation and ionization.
How does this nuclei become ion pair? It is when the neutron interact with it and...
I am torn between computational and experimental condensed matter physics for my PhD. My focus is on low dimensional systems (e.g. electron correlation/transport, broken symmetry at the boundaries). I'm currently in the process of applying for graduate schools, and so far, I've chosen all my...
On the premise that gravity transcends time, is there any reason that the effects of gravity that we observe as dark matter simply be the effects of gravity from the mass of standard matter from the past? For example the mass of our galaxy may not be enough to explain the effects of gravity...
In a simple example of two current carrying wires, there are mutual forces. Do we speak of the forces on each wire as action-reaction or as someone I'm debating with, each wire and the fields from the other wire as action-reaction? Or both? Thanks.
Hi. Could the local effects of gravity between nearby stars at the edge of a galaxy cause these stars to rotate around the centre of the galaxy more quickly than predicted if the prediction is based upon individual stars only. This effect would be similar to the way the Earth "drags" the Moon...
We want to calculate the ao/a(teq) of the equilibrium point between ρm and ρr (ρm= ρr )
My book solves it this way;
ρm(t) / ρr(t)= a(t) ⇒
⇒ (ρm/ ρr)teq =1 =
= (ρm/ ρr)o * a(teq)/ ao
I don't understand the a(teq)/ ao part. If ρm(t)= ρο/αo3 and ρr(t)= ρο/αo4 then it should be
ρm(t)/ ρr(t) =...
After watching a two-part program Everything/Nothing, a thought occurred to me when the discussion turned to particles popping in and out of 'empty' space. Could these particles be numerous enough in the vast space between stars to be responsible for the gravity holding stars together in...
Hello, I’m not a physicist or studying physics in school; I’ve just read some books and have some questions that I was hoping someone could help with. Sorry if they’re a little basic.
I’m trying to understand how tightly coupled matter is to spacetime. In other words, if you could look at a...
You're on Earth. You throw a ball and watch its trajectory. It's curved. That's because the Earth is curving space-time at every point along the trajectory. But the Earth itself is not present along the trajectory - there is no matter along the trajectory (let's ignore the air and any radiation...
Hi,
I don't know much about the standard model but I'm asking out of interest. Why do we actually need a Lagrangian for the standard model? Surely when you apply the relevant Euler-Lagrange equations, you end up with a variety of equations like the Maxwell equations or Dirac equations. Why...
What would happen if a black hole made entirely from anti-matter merges with another black hole made from normal matter? Since most of the product left over from the annihilation is in the form of light (gamma rays) would the black hole lose mass?
Hi,
I was studying soft matter physics when a question arose between a friend and me. Namely if red blood cells can be considered to be a colloid. Colloids as it was presented to us had 3 criteria: high diffusion so the particles wouldn't form a sediment, a small reynolds number and a surface...
Just trying to get to the bottom of a thought.
If glouns interact with each other or itself, could there be a multiple glouns orbiting each other?
Could this orbit create acceleration, and mass, and create quarks? Or possibly more gluon mass?
My question is about dark matter and how we guess it is working. I do not have a huge understanding of this but given a few things I have been lead to understand I would like to ask a few basic questions to better understand.
My question will start with antimatter;
Antimatter supposedly would...
Help me first understand the physical Universe that these twins live in. Has anybody ever measured physical matter from a different time frame other than the present moment? In other words, is there physical matter existing in a time other than the present moment?
If there is no evidence of...
Dear all,
in the context of my teaching I was wondering what exactly the explanation is of how a mirror works at the atomic level. Apparently, the fact that reflecting materials are often also good conductors and hence big energy bands helps reflecting the photons. Does someone know a nice set...
I guess you can say I’m a long way from complete an engineering degree cause I haven’t even taken trig or calculus. With that being said I was wondering is it better to take calculus at a community college rather than a university? Reason I'm asking is because I heard this from other people I've...
I thought this article was interesting (and here).
It made me think, if a transformation is sufficient to eliminate or create Dark Matter... Then the mystery of the existence of Dark Matter would become a mystery of why all of the other distance measurements are wrong in a universe without Dark...
Summary: Dark matter, the elusive mass that makes up most of the universe, doesn’t interact with light. Is this because it travels faster than light itself?
I have been working on the maths and the theory for several months now in order to discover the nature of dark matter. By rearranging and...
The first law of thermodynamics states that matter can only be transferred from one state to another, and cannot be truly destroyed.
What happens to matter consumed by a black hole? What happens to it and where does it go? Does the first law still hold true?
I have seen the term "slight preponderance" used many times to account for the apparent imbalance of matter and antimatter. I am not aware of the scientific justification for this however. Indeed, I have recently watched a lecture where, again, it is stated that we live in a matter universe. How...
Summary: I am writing a story that features space warfare. I was wondering does a big ship perform better than smaller vessels?
I'm just a writer (well wanting to be one with my poor grammar) so I don't know much about engineering or space at all.
So space is massive, so battles in space will...
Ok, this question is prompted by watching a TV program on the Big Bang - sorry!
Right after inflation, there was a flood of matter/anti-matter. The matter/anti-matter went through a period of annihilation but there was a residual amount of (anti-)matter left that has become our physical...
The summary pretty much says it all: How is dark matter, responding to gravity, thought to have formed filaments and walls--the scaffolding for the large scale structure of the universe--rather than random clumps? I can understand how scattered matter might not coalesce while exchanging...
We know that observed helium abundance constrains the amount of baryonic matter. Leaving that aside, is there any fundamental constraint on how much baryonic matter can exist in the universe, without changing the observed structures or physics of the universe? If there were only baryonic matter...
Specifically, if you took all the regular matter that we believe to be in the universe and condensed it down to ‘neutron star’ levels of compression (Rather than ‘black hole’ levels)...
How big a sphere would it make?
I’ve always wondered, but never seen an answer posted anywhere
Hopefully...
Is there a possibility that there are stars and planets that are composed entirely of DM?
How would we detect such stars or planets?
Well, I am not sure about stars, as the definition of a star depends on its fuel that it uses, I guess.
Summary: massless particles (or at least photons) are attracted to other photons and to matter, but which is most attractive, and why ...
Summary: massless particles (or at least photons) are attracted to other photons and to matter, but which is most attractive, and why ...
I am really...
No I'm not dumb, just confused. I keep reading that mass is the amount of matter. So is a 1kg mass matter? Is mass the stuff made of things . So when we say 1kg are we talking about the material? Or is mass the measure of how much? Looking for basic help. I always think about mass as how much...
Hello everyone, I'm a Physics student on a gap year, doing a bit of work ATM.
I'm going to come back in October this year to do a one-year Masters' at Cambridge, and I'm faced with a tough choice:
A) Specialize in Astrophysics/cosmology, which is something that I'm not as good at, but really...
Good morning! I hope you are all well! I am currently in my second year of pursuing a Bachelors of Science in mechanical engineering. I originally planned to take as many classes as I could each session (year round), but I quickly burned out each time. I was overwhelmed each session by the large...
Curious if the ongoing studies of black holes at the centers of galaxies, like the Event Horizon Telescope, might provide some clues about the nature of dark matter. Tried googling this, but all I get is articles debating, mostly to the negative, the hypothesis that dark matter might be...
One thing about terminology that I think c/should be changed for Continuum Mechanics:
1) 'Ideal Fluid' Describe Behavior of Matter in Phase States of liquid/gas and sometimes Bulk-Solid:
-continually deform under applied shear stress or external force
-usually zero shear modulus
-behavior can...
Two recent studies have found galaxies with little or no apparent dark matter, indicating modifying gravity can't work.
https://iopscience.iop.org/article/10.3847/2041-8213/ab0e8c
https://iopscience.iop.org/article/10.3847/2041-8213/ab0d92/meta
Hello!
Dark Matter (if exists)(if it is in form of particles - collisionless) could also be attracted by Black Holes (or Neutron Stars) and form accretion disk. I would like to discuss possible properties of such hypothetical object.
DM particles could be trapped and settled in around...
Not sure who this is he may be a mondian but it is an alternative view.
arXiv:1903.11217 [pdf, other]
Is dark matter fact or fantasy? -- clues from the data
Philip D. Mannheim
Comments: Essay written for the Gravity Research Foundation 2019 Awards for Essays on Gravitation
Subjects...
From what I have read gravitational waves are caused by the acceleration of massive object causing ripples in space time. What specifically causes this, and how does general relativity predict these. Does it have to be a high density of matter, or a large amount of it. How do these waves affect...