Questions tagged [low-temperature-physics]
The low-temperature-physics tag has no usage guidance.
78
questions
0
votes
1
answer
42
views
How do we do experiments on gases at zero Kelvin?
We say that at temperatures very close to absolute zero (nano or pico Kelvin) there is no gas, so how do we do experiments on gases at zero Kelvin, and why is Bose-Einstein described as a gas?
1995 – ...
- 159
0
votes
2
answers
59
views
How much energy does it cost to cool an atom to close to 0K?
I read that for many Quantum experiments with Atoms it is necessary to cool them to close to $0K$. How much energy does that cost roughly? Is there a formula which gives a lower bound?
- 1,228
2
votes
1
answer
122
views
Heisenberg's uncertainty principle in frames of reference with different velocities
The Heisenberg's uncertainty principle
\begin{align}\Delta x \Delta p \geq \frac{\hbar}{2},\end{align}
states that two canonically conjugate variables can't be measured simultaneously with arbitrary ...
- 316
-5
votes
1
answer
118
views
Is superconductance restricted to an extremely low temperature? Or can it be effectively replicated using some other technique?
A type of electrical amplifier is proposed in which only magnetism and it’s analogous current exists for the most part. There is no voltage and no wattage (to speak of) in which electricity has to ...
- 1
-1
votes
2
answers
101
views
Why liquid helium boils as its temperature is lowered?
Water boils when heated. Liquid helium boils when cooled. Not only that. It boils initially and then stops. Why?
- 9,285
26
votes
3
answers
5k
views
What is cold wind?
As per my understanding, temperature is the movement of particles in an environment. A highly energetic environment where particles possess high energy has a high temperature,
and low energy means low ...
0
votes
2
answers
208
views
At absolute zero temperature, we see that the electrical resistivity of a metal is not zero - Why? [closed]
I do know that for a perfect conductor, the electrical resistivity is zero at absolute zero temperature. But for an imperfect conductor (e.g. that we use in daily life) it is not zero even at $T=0^{\...
- 153
1
vote
0
answers
45
views
Gravitationally-driven electrical potential differences in conductors
This question asks
Free electrons in a metal are attracted by gravity towards Earth. So why don't they lay down to the bottom of the conduit, like sediment at the bottom of a river?
The current ...
rob♦
- 71k
2
votes
1
answer
69
views
How $^3\text{He}$ atoms remove thermal energy from surrounding environment in dilution refrigerator?
I am trying to understand how a dilution refrigerator works.
I understand that $^3\text{He}$ atoms are pumped out of the diluted phase and to reestablish an equilibrium, new $^3\text{He}$ move there ...
- 995
4
votes
0
answers
122
views
What happens to isothermal compressibility at zero temperature?
In chapter 11 of his book on thermodynamics, Callen states that Nernst postulate implies the isothermal compressibility (denoted as $\kappa_T$) of any system vanishes as its temperature approaches ...
- 2,331
2
votes
0
answers
69
views
As of 2021, what is the latest record for lowest temperature?
From what I understand in this article, absolute zero(0 kelvin) is an impossible task.
They state that the lowest temperature achieved in the laboratory was 0.1 nanokelvin.
The lowest temperature ...
- 385
1
vote
0
answers
50
views
Markov approximation at low temperatures
I'm interested in a two-level system in contact with a reservoir of harmonic oscilators, described by the following Hamiltonian:
$$
\hat{H}=\hat{H}_S+\hat{H}_R+\hat{H}_{RS}=\hbar\omega_0\hat{a}^\...
- 131
0
votes
2
answers
195
views
How to perform experiments near absolute zero temperature when the background temperature of the universe is 2.7 K?
The cosmic microwave background (CMB) radiation as a remnant from an early stage of the universe (Big Bang) is filled all space and has a thermal black body spectrum at a temperature of $2.72548±0....
- 4,378
0
votes
1
answer
30
views
MOSFET current at very low temperature (4K)
I am trying to model the current at low T. To do so I need to compute the integral of fermi dirac statistics multiplied by the conductivity, with respect to energy:
My problem is that I cannot ...
- 1
1
vote
0
answers
52
views
Are there substances that behave as perfect conductors but not superconductors?
Does there exist substances which below a certain temperature becomes as a perfect conductor but not a superconductor? A superconductor is both a perfect conductor as well as a perfect diamagnet. If ...
- 9,285
0
votes
2
answers
281
views
What happens to the electrons mobility when metals get cooled down?
I know conductivity increases, but what happens to the electrons on the inside?
1
vote
0
answers
205
views
Pomeranchuk Effect
Pomeranchuk effect poses a paradox of order by disorder phase-transition. The liquid Helium-3 is in a liquid form close to absolute temperature. For high enough pressure, as you increase the ...
- 121
1
vote
1
answer
48
views
Inverse temperature and Lennard-Jones model
I am a mathematician and I am trying to understand the intension behind the inverse temperature and the activity (or intensity).
Consider e.g. the Hamiltonian [with (12,6)-Lennard-Jones pair potential]...
- 13
3
votes
0
answers
76
views
RG for Interacting Fermions - Shankar's Review
I want to ask a question about a rather famous review paper on RG by Shankar.
On page 92-93 of this paper, Shankar provides a version of RG for spinless fermions in $d=2$ dimensions with a soft cut-...
- 734
1
vote
0
answers
16
views
Calibration of Hall Effect Measurement using Standard Reference Material (NIST)
I would like to calibrate a low-temperature Hall effect measurement using a Fe SRM.
Are there any standardized Hall measurements of SRM's available?
- 11
1
vote
0
answers
58
views
Vortex solution of Laplace equation (XY model)
The hamiltonian of XY model, which is closely connected with BKT - transition is following:
\begin{equation}
H=\frac{J}{2} \int \text{d}^2 r \, \nabla \varphi \cdot \nabla \varphi, \quad \...
- 321
1
vote
0
answers
156
views
What are good books and other resources to study the Cryogenics?
I'm beginner in cryogenics. Also please suggest something which will be useful for study of Electronics at Cryogenic Temperatures.
0
votes
3
answers
920
views
Do metals at low temperature follow Ohm's law?
I think metals at low temperature do not follow Ohm's because of superconductivity. Is it true? What about metals at high temperature?
- 13
4
votes
2
answers
72
views
Can a permanent magnetic become too cold to function?
I have heard that it's possible for a permanent magnet to become too hot to function, especially if it reaches melting temperature however I cannot find much on the affect of cooling a magnet ...
- 448
2
votes
1
answer
103
views
Understanding why a substance cannot be at $0K$
I am trying to understand why it is that a substance cannot have a temperature of exactly 0K. My text book's explanation is that since internal energy is the sum of the kinetic energies of the ...
- 55
1
vote
0
answers
96
views
Reaching 0 K in a "Finite number of steps"
Let me preface this by saying that I don't really like the third law of thermodynamics very much.
Its not that I believe its not true, its just that it feels non rigorous, all its different ...
- 1,090
2
votes
2
answers
186
views
Is it really true that valence band is completely filled at zero temperature?
Is it really true that valence band is completely filled at null temperature?
Indeed, I would think that if we apply an electric field, this would give some energy to the electrons from the valence ...
0
votes
1
answer
48
views
How do we cool gases to the $mK$ range?
When we set new records for coldest temperature in the universe, we usually do it with gases (see: https://physicsworld.com/a/millikelvin-cooling-of-large-molecules-is-no-myth/)
How do we pull this ...
- 525
2
votes
1
answer
2k
views
Why is a liquid nitrogen canister not cold on the outside when inside the temp of the sealed liquid is -320F? [closed]
...or IS the inside temperature ambient temperature? Surely the insulation of the container is not sufficient to seal in that cold? I.e. if you had an unsealed bowl of liquid nitrogen with the same ...
4
votes
2
answers
6k
views
What happens to a liquid nitrogen canister under pressure if left at room temperature? Will it eventually explode? Or forever stay cold?
If I put a strong, sealed container of liquid nitrogen on a table at room temperature, will it always stay cold? Or will it slowly heat up until the canister bursts? Assume it is an extremely strong ...
- 51
4
votes
2
answers
632
views
Does quantum gases obey ideal gas equation $ PV= nRT$?
At extremely low temperature, does an ideal gas of bosons or fermions obey the ideal gas equation, $PV= nRT$?
- 733
2
votes
0
answers
133
views
Would there be any current if an electric circuit is cooled to absolute zero?
My question is if I got a superconductor and cool it to absolute zero at least measurable by today's tool, it should have no electrical resistance but then would there be any current when there is a ...
- 11.4k
1
vote
2
answers
269
views
Why is -273.15 °C the low temperature limit for the universe? [closed]
According to Ideal Gas Law the lowest temperature of an ideal gas can be $-273.15 °C$. This temperature is also considered the lowest temperature in the universe. But it is the lowest possible ...
- 1,350
0
votes
3
answers
483
views
Is there a temperature-pressure phase diagram of carbon dioxide for the lowest temperatures and pressures?
The image above will probably be well known to visitors of Wikipedia on CO$_2$.
But is there a temperature-pressure phase diagram of CO$_2$ for still lower temperatures and lower pressures as well ?...
- 432
0
votes
1
answer
98
views
Is there a maximum frequency at which hysteresis appears?
If a ferromagnetic material is immersed in an alternating magnetic field at frequency $\omega$, the material will follow a hysteresis cycle at that frequency. But if that frequency is high enough, the ...
- 544
2
votes
1
answer
553
views
Canonical ensemble near absolute zero
In the canonical ensemble for an ideal gas of $N$ bosons, the partition function for $T\to 0$ scales like
$$Z\sim e^{-\beta\epsilon_0N},$$
when $\epsilon_0$ is the lowest (non-degenerate) single ...
user56224
1
vote
1
answer
119
views
Do photons have a minimum energy in relation to the expansion of the universe?
As the universe expands, background photons lose energy. Can that keep happening? After all, you can never reach zero temperature. So what happens to photons in the limit?
- 885
1
vote
1
answer
65
views
Is there any positive temperature from which superconductivity ceases?
From what I understand about superconductivity, it is due to a coupling between Cooper pairs and phonons. At the absolute 0, there is no phonon, so I assume superconductivity cannot exist at that ...
2
votes
0
answers
50
views
What are some empirical ways to estimate the absolute 0 in temperature?
Back in the 1600's and 1700's, people could estimate the existence of an absolute 0 in temperature by using the ideal gas law $PV=nRT$. By holding $P$ and $n$ constant and by observing how much gases ...
0
votes
2
answers
129
views
Can't we stop the time? [duplicate]
Time is called as a measurement of difference between two or more incidents. So if we stop happening incidents can't we stop the TIME? Eventhough it's impractical, I mean if we reduce the temperature ...
3
votes
1
answer
240
views
Is the $\lambda$ point in superfluid helium understood?
When liquid helium is cooled below a certain temperature, it undergoes a second phase transition from He I to He II. The specific heat spikes at the famous lambda point. Is this spike in the specific ...
- 10.9k
4
votes
0
answers
291
views
Is there any example of a real-life system which violates the "third law" of thermodynamics while remaining at equilibrium?
I assume the following statement for the "third law" of thermodynamics:
$$\lim_{N \to \infty} \lim_{T \to 0} \frac{S}{N} = 0 \tag{1}\label{1}$$
That is to say, I am considering those systems with a ...
- 15.4k
0
votes
1
answer
76
views
Why does Aquafina explode when frozen?
I put two Aquafinas in the freezer this morning "for a few minutes" but then forgot to take them out.
Tonight, I opened the freezer. Both cans had exploded; on one, the top was blown off; on the ...
0
votes
0
answers
107
views
What is the radiative cooling rate at extremely cold temperatures?
Consider a spherical object in empty space, in the far future where the CMB can be entirely neglected. What is the cooling rate as it approaches radiative equilibrium?
Here is what I got so far:
The ...
- 27.6k
2
votes
0
answers
35
views
Splitting of Forces at Low Temperatures?
Since the electroweak force split from the strong force during the electroweak epoch then the electroweak force split into the electromagnetic and weak force during the quark epoch, is this an ...
- 403
0
votes
1
answer
138
views
Wind speed and molecule drift speed
My question regards this answer, more precisely this assertion:
If all the air molecules, by some strange coincidence, all moved in the same direction 2 things would happen. One, the air would get ...
- 101
1
vote
0
answers
30
views
Phase diagram of $\text{He}^3$ at low temperatures
The $p(T)$ phase diagram of $\text{He}^3$ at low temperatures is given here:
https://de.wikipedia.org/wiki/Pomerantschuk-Effekt#/media/File:Phasendiagramm_He3log.gif
How can one physically explain ...
- 185
3
votes
1
answer
2k
views
Gas at absolute zero
According to Charles's Law, the volume of gas is proportional to temperate at constant pressure. So, the volume of a gas decreases as temperature decreases.
Then, in theory, as the temperature ...
- 95
2
votes
0
answers
35
views
How well do pressure measurements translate to temperatures?
At low temperatures we measured the changing pressure in a cryostat and converted these to temperatures using the function given by Donnelly (p1267; doi). But it seems that this is only accurate if ...
- 939
0
votes
0
answers
136
views
Why does an AC current cause a resonator to vibrate?
This is an experiment I'm going to be doing, and I can't quite get my head around it.
The experiment is performed at very low temperatures to investigate the properties of superfluids. There's a ...
- 939