Use this tag for questions related to mass and any materials that have volume and the objects they constitute.
Questions tagged [matter]
398 questions
209
votes
4 answers
Why doesn't matter pass through other matter if atoms are 99.999% empty space?
The ghostly passage of one body through another is obviously out of the question if the continuum assumption were valid, but we know that at the micro, nano, pico levels (and beyond) this is not even remotely the case. My understanding is that the…
Bryson S.
- 3,996
198
votes
15 answers
Why does space expansion not expand matter?
I have looked at other questions on this site (e.g. "why does space expansion affect matter") but can't find the answer I am looking for.
So here is my question: One often hears talk of space expanding when we talk about the speed of galaxies…
SoulmanZ
- 2,095
51
votes
8 answers
Why isn't dark matter just ordinary matter?
There's more gravitational force in our galaxy (and others) than can be explained by counting stars made of ordinary matter. So why not lots of dark planetary systems (i.e., without stars) made of ordinary matter? Why must we assume some…
Andrew Beatty
- 613
32
votes
3 answers
Is Dark Matter called "Matter" only because of gravity?
As far as my understanding goes, dark matter is nothing but an amount of gravitational force, from yet unresolved/undiscovered source(s), needed to explain some observed attributes of our universe. Then, is it called "Matter" only because of…
Gulshan
- 713
24
votes
3 answers
Is it possible to obtain antiwater from antihydrogen and antioxygen atoms? And how is its property w.r.t. the ordinary water?
I am interested in experimental physics and looking for information about the above question.
Dirk
- 361
23
votes
1 answer
How do we know Dark Matter is non-baryonic?
It seems widely stated, but not thoroughly explained, that Dark Matter is not normal matter as we understand it. Wikipedia states "Consistency with other observations indicates that the vast majority of dark matter in the universe cannot be baryons,…
Ehryk
- 3,311
21
votes
5 answers
How would neutron matter appear to the naked eye?
Neutron matter is matter comprised entirely of neutrons, as it exists in neutron stars.
Most optical phenomena encountered in everyday life, such as light reflection and spectral absorption (i.e. color appearance) are the result of mechanisms…
user32035
19
votes
2 answers
Can matter be described as the result of the curvature of space, instead of vice versa?
Can matter be described as the result of the curvature of space, rather than the curvature of space being the result of matter, and energy being the cause of the curvature of space?
Kane
- 191
19
votes
4 answers
Could quantum fluctuations spawn real matter?
Would it be plausible for fluctuations in the QED vacuum to spawn actual matter (such as quarks, electrons the constituents of a hydrgen atom) given enough time and space?
Justin
- 763
19
votes
2 answers
What did Tesla mean by "there is no energy in matter"?
I was reading "THE ETERNAL SOURCE OF ENERGY OF THE UNIVERSE, ORIGIN AND INTENSITY OF COSMIC RAYS" by Nikola Tesla, and he states:
"There is no energy in matter except that absorbed from the medium."
What does he mean by this?
Einstein's famous…
Jordan Goulet
- 449
17
votes
4 answers
What would happen to matter if it was squeezed indefinitely?
I hope that this is a fun question for you physicists to answer.
Say you had a perfect piston - its infinitely strong, infinitely dense, has infinite compression ... you get the idea. Then you fill it with some type of matter, like water or dirt or…
Mardymar
- 417
15
votes
5 answers
Does a rock use up energy to maintain its shape?
A rock sitting on land, the ocean floor, or floating in space maintains its shape somehow. Gravity isn't keeping it together because it is too small, so I'm assuming it is chemical or nuclear bonds keeping it together as a solid. If not it would…
CramerTV
- 847
15
votes
4 answers
When does 'energy' turn to matter?
I always hear about matter converting to 'energy' - fusion, fission.
When does it go the other way around? What conditions lead to it? Are there reproducible experiments on this topic?
Aaron Anodide
- 573
15
votes
6 answers
Why must a singularity form inside a black hole?
What is the exact reason that normal matter can not exist within an event horizon?
I can understand how a super-dense object like a neutron star could accrete mass until its physical radius is less than its Schwarzschild radius and an event horizon…
Bohemian
- 277
13
votes
4 answers
Is it possible to create matter?
Is it possible to create matter? In a recent discussion I had, it was suggested that with enough energy in the future, "particles" could be created.
It seems like this shouldn't be possible due to conservation but perhaps I could be wrong. Would…
codedude
- 238