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Questions tagged [low-temperature-physics]

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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 ...
38 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 ...
1k 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 ...
831 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 ...
200 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, $PV= nRT$?
37 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 ...
99 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 ...
80 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 ?...
39 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 ...
197 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 ...
80 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?
57 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 ...
44 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 ...
116 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 ...
80 views

System of $N$ bosons

What precaution needs to be observed in writing down an expression for the total number of bosons $N$ valid at low temperatures?
102 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 ...
169 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 ...
60 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 ...
87 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 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 ...
87 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 ...
28 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 ...
674 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 ...
34 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 ...
102 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 ...
117 views

What's the role of BEC in superfluidity?

I'm writing about superfluid $^4$He. I've seen in some places that the transition to superfluid is attributed to Bose-Einstein condensation, but then in others that this model needs a massive amount ...
99 views

Calculating heat leak in a cryostat

I'd like to optimise a cryostat insert. It will be used for resistance measurements at around $4.2K$. I'm having a little trouble getting started with my constraints. I need to calculate the largest ...
180 views

Expansion of Bose Distribution at low Temperatures [closed]

I have a phononic system with its distribution $$N_B(E,T) = \frac{1}{e^{E/k_BT}-1}$$ where $E$ is the energy and $T$ the temperature of the system. I'd like to know how to make an expansion of this ...
614 views

Do cold objects emit radio waves? [duplicate]

I remember from my basic physics class 3 years ago that (every?) object naturally emits EM radiation. I also remember that temperature is directly proportional to the frequency of the EM waves. Does ...
4k views

Are room temperature superconductors theoretically possible, and through what mechanism?

At the moment, the highest critical temperature superconductor known to science (or myself, at least) is mercury barium calcium copper oxide. With a $T_{c}$ of roughly 133 K, that's well above the ...
244 views

Measuring very small temperature differences

Can one use a thermometer with $\pm$5 mK accuracy to measure a temperature difference of 2 mK (the measurement is near 100 mK temperature on a sample on an ADR)? Using the same thermometer, I am ...
254 views

“Big Crunch” Ending of Universe?

So, I am reading Introduction to Modern Cosmology by Andrew Liddle and have just learned that the universe is cooling as it is expanding. Now, I am mathematician knowing very little about physics, but ...
65 views

How extremely low temperatures (near absolute zero) are actually measured [closed]

How do the industrial or laboratory thermometers for this purpose work like: what effects are based on, what are other alternatives how accurate they all are
904 views

The Correct Statement of the Third Law of Thermodynamics

The Third Law of Thermodynamics can be stated in various ways, one of which is: The entropy of a perfect crystal at absolute zero is exactly equal to zero. Is this true for only "perfect ...
12k views

Why is Helium so hard to liquify?

By the end of the 19th century all gasses had been liquefied apart from helium (He). What is it about helium that makes it so hard to liquefy compared to the other gases? And why does it need to be ...
681 views

Entropy of fermi gas at $T=0$

Does the entropy of ideal fermi gas go to zero , in accordance with third law of thermodynamics? Consider a system of three fermions in a 3D box. The first fermion goes to the ground state of the ...
31 views

How do the grids screen out inelastically scattered electrons in low energy electron diffraction

This is a wiki article about what I am talking about https://en.wikipedia.org/wiki/Low-energy_electron_diffraction. I was just wondering how the grid screens screen out the inelastically scattered ...
563 views

How are LIGO mirrors cooled?

The recent LIGO announcement Observation of Gravitational Waves from a Binary Black Hole Merger has some technical details about LIGO. For example, LIGO is a modified Michelson interferometer. The ...
249 views

At the lambda point, why does specific heat capacity tend to infinity?

The specific heat capacity is the energy required to raise the temperature of unity mass by 1K, if at the lambda point all the bosons occupy the lowest quantum state, shouldn’t the specific heat ...
1k views

Why is chemical potential, μ=0 when calculating critical temperature of BECs?

How do we justify taking the chemical potential, $\mu$ as $0$ when calculating the critical temperature of Bose-Einstein Condensates (BECs)? I apologise as I do not how to use LaTeX, for if I did the ...
209 views

Elastic properties of materials at low temperature

It is common knowledge that materials are more brittle at low temperature. But does it apply also on elastic deformations or is it just matter of plastic deformations? Practically: Is it possible to ...
351 views

Is there a database or a classification of High-temperature superconductors?

I was wondering if there exists a list with all (or most of) the High-$T_c$ superconductor materials. In particular I'd like to know if there are databases or review that classifies them by their ...
653 views

1D superconductivity does not exist even at zero temperature?

In class Professor claimed that 1D superconductivity does not exist even at zero temperature. I did a preliminary search and found papers on 1D superconductors. Did I or the Prof make a mistake or ...
652 views

Electrons and photons at absolute zero?

I know that molecules can't move at absolute zero (hypothetically of course). But what happens to electrons and photons?
1k views

What is the temperature of the event horizon?

In a discussion with my son about absolute zero, we arrived at the conclusion that the event horizon might be the place to look, as it "absorbs?" all energy, including light. Found this in the ...
95 views

does it take more energy to lower the temperature of something as you get closer to absolute 0?

Instinctively I would assume it would take exponentially more energy to get from 0.01 to 0.001 (Kelvin) then it would to get from 2 to 1 (Kelvin). Otherwise it seems like it would be quite easy to get ...
67 views

How to choose which atoms to cool using optical cooling technology?

Which atoms are easiest to cool down to very low temperatures (e.g. mK)? Which quantities does one need to look at? My very naive guesses so far are: Their mass: the heavier they are they least ...
2k views

Is there any other superfluid element except helium?

Is there any other superfluid element except helium? Everywhere we see and speak about superfluidity, we just speak about superfluid helium. but is't there any other element or material or system ...