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Messages - hamdani yusuf

Pages: [1] 2 3 ... 15
1
New Theories / Re: what is temperature?
« on: 09/05/2022 13:00:33 »
Quote from: hamdani yusuf on 09/05/2022 10:09:39
Why don't polyatomic gases rotate nor vibrate at low temperature?
Because the energy available to them is less than that required to get them  to rotate or vibrate.

Quote from: hamdani yusuf on 09/05/2022 10:12:32
Is vibrational energy also quantized?
Yes.

Quote from: Eternal Student on 09/05/2022 12:18:56
QM is not important. 
Yes it is.

Quote from: hamdani yusuf on 09/05/2022 10:12:32
What's the minimum non-zero quantity of of rotational energy?
It depends on the molecule.
For N2 I think it's about 10^-4 eV.
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2
New Theories / Re: what is temperature?
« on: 07/05/2022 16:51:41 »
Quote from: hamdani yusuf on 07/05/2022 04:13:59
As an example, an object absorbs 2 Joule of energy. 1 Joule is converted to potential energy, and 1 Joule is converted to kinetic energy.
Another object with same mass absorbs 2 Joule of energy. 0 Joule is converted to potential energy, and 2 Joules is converted to kinetic energy.
According to the definition above, the temperature of the object increases corresponding to the increase of kinetic energy. Hence the second object increases its temperature twice as much as the first object.

Correct.

An increase of internal potential energy would correspond to a partial or total change of state within the body.

I encountered this when measuring radiation dose with a calorimeter. Dose is defined as energy aborbed per unit mass, and the principal concern for radiation protection and radiotherapy is the measurement of dose to water. For practical simplicity most primary standard calorimeters use graphite as the absorber because it is mechanically stable and has about a tenth of the specific heat capacity of water so undergoes a larger temperature change (a lethal dose of ionising radiation raises your body temperature by about 0.001 degree - my task was to measure that to ± 10-6K). One of my colleagues built a water calorimeter - rather less portable device but clearly worth directly measuring the quantity of interest rather than trying to derive it. Problem was that the water calorimeter generally measured about 3% less than the graphite calorimeter, though both were calibrated to  ± 0.01%. I thought the difference was due to "virgin" water forming metastable polymers when irradiated, because the defect gradually decreased with extended irradiation to high doses but later work has revealed all sorts of complex chemistry possible with just H and O atoms and plenty of energetic photons.
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3
Just Chat! / Re: What is your main area of interest or expertise?
« on: 03/05/2022 23:22:08 »
Quote from: Hamdani Yusuf
Philosophy should be the basis of our biggest and most influential decisions.
It has been noted that if you recursively trace the first significant word in a Wikipedia article back to its Wikipedia article, you get back to the Wikipedia entry on Philosophy (in about 95% of cases).

So perhaps Philosophy is the basis of our biggest and most influential Wikipedia articles? (in a roundabout sort of way...)
See: https://en.wikipedia.org/wiki/Wikipedia:Getting_to_Philosophy
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4
General Science / Re: Is 2 really prime? If so, why isn't 1?
« on: 29/04/2022 23:03:03 »
All primes are odd
Except 2
Which is odd, because it's even.
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5
General Science / Re: Is 2 really prime? If so, why isn't 1?
« on: 28/04/2022 18:22:32 »
Hi.    Fantastic diagrams.   Great that you're making an effort to engage the audience with some Mathematics etc.
I wish you well.

I'll hide everything else under a spoiler because it's a bit dull and might prevent others from making their comments.

Spoiler: show
   The main reason for not counting 1 as a prime number is that most of the results we have about prime numbers, or more generally about whole numbers, won't work if you tried to state them as they are now and continued to use the term "prime number" in that statement of the result.   The decision not to include 1 as a prime number wasn't really done because of some elaborate definition or way of identifying what the primes are supposed to be.   I don't think following a pattern that emerges from dots had a lot to do with it.    Instead, it was done because it's not all that useful to have 1 included in the set.

    Another way to say this is that there's no reason you couldn't include 1 as a prime number if you want to.   You go right ahead and do that.   You don't even need to make up a good reason like drawing an arrangement of dots.   For whatever reason, you can put the number 1 into the primes if you like.   The only change that will result is that mathematicians will stop quoting their results by referring to "prime numbers" .  Instead they will identify a slightly different set of numbers, let's call them "Q-rimes" and their results will be stated with respect to that.   The Q-rimes will naturally be your Primes excluding the number 1.  So, the only thing that will have happend is that you will have changed the name we apply to describe what is currently called the prime numbers.

    I suppose to finish this I should give at least one example of a result that is useful and easily stated with reference to prime numbers (with 1 excluded but not if 1 is included).

     The fundamental theorem of arithmetic
Every counting number can be written as a product of prime numbers each raised to an appropriate (Natural number) power.   Furthermore, that respresentation is unique up to changing the order in which you perform the multiplication.

Example:     40  =  23 x  5
   If you try to write 40 as some other product of primes, let's say you allow yourself to use three prime numbers   p, q, r    such that   40  = pa x qb x rc     for some exponents  a,b,c   then you find that you can't,  there's no solution for that.     The fundamental theorem of arithmetic holds.
    However, if you allowed 1 to be a prime number then you can.....   One solution is to set p = 2,   q = 5, r = 1    and a= 3, b = 1, c= 2 .  That will be another representation of the number 40 as a product of primes:    40  =  23 x  5  x  12     and so the fundamental theorem of arithmetic doesn't hold.

Quote
Is 2 really a prime number?
    Actually 2 is another number that has very unusual properties even though it is prime.   It is often very useful and desirable for mathematicians to consider a subset of primes that doesn't include 2.   They call this set the "odd primes" and several theorems are stated with reference to  "odd primes" instead of just "the primes".  Alternative terms exist for this set and it's quite common not to bother naming the subset and just write a result as holding  "for all primes, p > 2".
   So 2 is a prime number but its certainly not typical of primes and there is a similar set, the odd primes, where you do just exclude it.


Best Wishes.
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6
Just Chat! / Re: What is your main area of interest or expertise?
« on: 11/04/2022 21:42:19 »
Quote from: Eternal Student
I'm still fairly surprised and impressed that you reply to so many questions or discussions in the Biology sections.
One view of biology imagines it to be a fantastically complex program, coded in DNA.
- The cell represents the computer which executes the program (unlike silicon computers, it also has programs for self-repair)
- You can see parts of the program that are no longer executed, or which have been corrupted by viruses
- Each little computer interacts with others around it, at various levels up to whole ecosystems...
- Not entirely different from the telecommunications systems that I work on...
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7
New Theories / Re: what is temperature?
« on: 03/04/2022 01:07:34 »
Hi.

   I really don't know why burgers have become important.  I was just going to back up to some earlier posts:

Originally a quote from @hamdani yusuf , re-used in a reply from Bored Chemist:
Quote from: Bored chemist on 02/04/2022 19:18:04
We know that a system can have many forms of energy. They are often classified as kinetic and potential energy. Which category does temperature fall into?

 Bored Chemist replied:
Quote from: Bored chemist on 02/04/2022 19:18:04
Neither.
That's why we call it thermal energy.
   That's old style.   Presumably you went to school roughly when I did but you (bored chemist) presented the article about re-defining temperature, so you've got to play fair here.
    The modern definition of temperature (in Kelvin post 2019) is trying to remove the need for such oblique references as calling something "thermal energy".  It does not step around declaring what that energy is at a microscopic scale and leave it open to all sorts of possible interpretations.   Instead it embraces the notion of microscopic statistical mechanics head on.

Alancalverd replied:
Quote from: alancalverd on 02/04/2022 18:41:29
Temperature is a measure of the mean kinetic energy of the molecules inside an object. It is not a measure of the kinetic energy of the whole object, or the potential energy of any stresses within it. If you input energy in such a way as to increase the mean kinetic energy of the molecules inside an object, you will increase its temperature. If you do something else, you won't.
    Which is much more in-line with the definition of temperature used in the modern Kelvin scale.
Temperature (in Kelvin post 2019) is very much meant to be a measure of the average kinetic energy of the particles of a system.   (At least for simple systems it will be.  Whether our Kinetic Theory is adequately developed to determine the behaviour of particles in all systems like solids, liquids or a gas of photons is a different question).  If you put energy into a system that doesn't change the k.e.of the particles then, as Alancalverd stated, you won't change the temperature of the system.
    However the issue remains murky:   To the best of my knowledge, the requirement for a system to be in equilibrium hasn't disappeared in the new approach to defining temperature.  If you put energy into a system (e.g. to raise electrons to an excited state or change something else about the system that might be considered as a potential energy change instead of kinetic energy change for the particles) then you must wait until an equilibrium is re-established before the system has a well defined temperature.  When the energy of the system is re-distributed and the principles like the equi-partition of energy apply, it is very likely that the average k.e. of the particles will have increased.   (I said "likely" not guaranteed to always happen, changes of state might be one example where you can put energy into a system but there is no change in temperature).

Speculation about changes of state:
The actual shared property (temperature) is the average energy per degree of freedom.
[Taken from  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4865254/  .  An article originally suggested by Bored Chemist ]

    How they (the community of scientists using the new definitions of the Kelvin scale) consider or determine temperature for systems that can show a change of state  (e.g. from gas to liquid)  should be interesting to see.  I haven't had time to look at this yet.  However, if the kinetic theory they use allows the gas to have, lets say 5 degrees of freedom (I chose 5 because that's easily explained by the models we have for a diatomic gas), while the liquid state only supports 4 degrees of freedom (which is reasonable because we assume particles in a liquid state have less freedom of movement and therefore less parameters describing their energy) then you can see that is possible for the system to have more total energy in the gas phase than the liquid phase but the   energy per degree of freedom,  i.e. the "temperature" can remain the same.  We have a possible explanation for latent heat, the system loses degrees of freedom during phase changes.
   Let's make it clear that I haven't had time to look at this yet, it just seems reasonable.   The new approach to defining a temperature scale (introduced since 2019) just wasn't in existence when I was studying thermodynamics.

Best Wishes.
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8
New Theories / Re: what is temperature?
« on: 01/04/2022 01:46:55 »
Hi.

Quote from: Bored chemist on 31/03/2022 23:16:13
This might be helpful.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4865254/
   That is interesting and I've only scanned through it so far.  I'll read more later.
   As far as I can see the latest revisions to the Kelvin temperature scale were made in 2019 and that paper or article was written in 2016.  I think they (the article referenced) are talking about the modifications that were about to bring the standard to what it is now.

    I think there's a mis-print in the article (first paragraph under the title Gas Thermometry) :

Gas thermometry relies on the statistical-mechanical connection between the three kinetic degrees of freedom of an ideal gas and thermodynamic temperature: ½ m〈v2〉 = 3kBT, where m is the mass of an atom and 〈v2〉 is the mean-square velocity of the atom.

   I'm fairly sure  that should be   ½ m〈v2〉 = (3/2) . kBT.

   Anyway, if you (@Hamdani) are really interested in the best way to define temperature it might be well worth having a look at that article and the simpler overview of the situation in Wikipedia.

Quote from: Bored chemist on 31/03/2022 23:16:13
It (the triple point of water) (together with the definition of absolute zero) is the only fixed point on the whole of the Kelvin temperature scale.
   The latest definition of the Kelvin scale for temperature won't require the triple point of water as a fixed point.
Since May 2019, that value (the triple point of water) has not been fixed by definition but is to be measured through microscopic phenomena
[Quote from Wikipedia]
    Even absolute zero,  0 K,  doesn't really fit the description of what we would have called a "fixed point" in the old days.  No experiment has to be done or object set up to that temperature to calibrate the scale.   That value just falls out naturally from the theoretical definition of temperature from statistical mechanics.  You also have no choice about what numerical value you assign to this temperature,  it couldn't be -10  or  +10 because it's got to be proportional to the average kinetic energy of particles (which is supposed to be nothing).   
    You don't really have any freedom to set any fixed points and corresponding numerical values at those fixed points for the temperature.   For example, if you use the equation   ½ m〈v2〉 = (3/2) . kBT,  to define temperature, T,  then the only way you can adjust the value of T for some pre-determined reference situation (like the average k.e. of the gas particles in an equilibrium mixture of ice, liquid and gas water, i.e. water at its triple point)  would be by changing the Boltzman constant.
    If I've read the article @Bored chemist  presented correctly,  the exact value of the Boltzman constant wasn't going to be fixed until 2018 (2 years after the paper was printed).  With the new value fixed, the triple point of water would be close to 273.16 Kelvin but there was no expectation that it would be exactly that value.

- - - - - - -
   There we go...  . I had no idea the way we think about temperature has changed that much and this recently.
Thanks again for the article @Bored chemist .

Best Wishes.
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9
Chemistry / Re: What element produces a heavy gas bubble?
« on: 30/03/2022 05:14:25 »
I did a number of acid test, the end results were almost always something different than the last, the one thing that was consistent were the bubbles and that's why I was curious as to what element might be producing the bubbles. No one can say why, but this pyrite has a thing for sphere shapes. Here are some photos of the bubbles in question.
* 1A.jpg (77.45 kB . 716x537 - viewed 1040 times)
* 2A.jpg (108.59 kB . 737x553 - viewed 1040 times)
* 3A.jpg (69.19 kB . 716x537 - viewed 1044 times)
* 4A.jpg (73.47 kB . 716x537 - viewed 1042 times)
* 5A.jpg (56.96 kB . 716x537 - viewed 1041 times)
* 6A.jpg (100.4 kB . 716x537 - viewed 1041 times)
* 7A.jpg (105.79 kB . 716x537 - viewed 1042 times)
* 8A.jpg (115.74 kB . 716x537 - viewed 1045 times)
* 9A.jpg (61.18 kB . 716x537 - viewed 1037 times)
* 10A.jpg (78.09 kB . 716x537 - viewed 1038 times)
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10
Physics, Astronomy & Cosmology / Re: Is there a net heat exchange between water and ice at 0 degree C?
« on: 20/03/2022 01:21:44 »
Hi all,
 Hamdani you raise a interesting scenario,

BC
Quote from: Bored chemist on 19/03/2022 17:32:30
Quote from: hamdani yusuf on 19/03/2022 16:22:39
Energy will flow until equilibrium is achieved.
It was already at equilibrium.

I am not sure that statement is totally correct, if you consider the energy imbalance between the two sides as described,
for example the latent heat/energy is unbalanced as is the kinetic energy of the molecules, also the density's.   
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11
New Theories / Re: How a Snowflake Works
« on: 17/03/2022 12:57:15 »
Quote from: Origin on 17/03/2022 12:31:24
Quote from: hamdani yusuf on 17/03/2022 09:47:55
You can answer them here, or alternatively, post your answers in my thread.
https://www.thenakedscientists.com/forum/index.php?topic=80604.0
Seriously?  You hijack the thread and then try to direct readers to your own thread.  Very rude, reported.
To be fair, the OP asked for it- literally.
Quote from: thebrain13 on 15/03/2022 22:35:16
I challenge the forum, to pick anything in physics I can't explain in a simple "why" language. (not a math contest, my physics major was enough). The only rules are to be respectful and pick something most people know about.
And "Temperature" is one thing that can be tricky to define.
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12
Just Chat! / Re: Is there a universal moral standard?
« on: 06/03/2022 14:43:00 »
Choosing whom to kill would raise some moral dilemmas. Merely ridding the world of priests, politicians and philosophers would make life more peaceful but wouldn't have much impact on sustainability. You might then start on pensioners, but we have a limited life span anyway, and have contributed to the public good through our taxes and investments, so we should be allowed to enjoy our pensions. Companies that rashly introduced early retirement to save money on the short term often found that, within a year or two, everyone who knew anything useful or had acquired a significant skill, had disappeared. 

But every baby is a net consumer for about the next 20 years, without having contributed anything. So a baby not born is a significant exchequer saving and improvement in the future quality of life for those already here.

Killing people takes effort and organisation, and doing it on a big scale can pose problems disposing of the bodies. Not making babies is the perfect "do nothing" option, with no waste product.
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13
General Science / Re: evolution
« on: 23/02/2022 04:34:53 »
Quote from: Kryptid on 23/02/2022 04:01:34
An alternative hypothesis might be that the beard offered some degree of protection in fights between men. I honestly have no idea how plausible that would be, though.
You might have some agreement out there:
Quote from: Elaine Morgan
Within the context of the AAT, losing facial hair is advantageous for swimming. One of the little talked about huge holes in traditional PAs non-AAT theories is the belief that males played a major role in procuring food. I don't know of any other species where males obtain food to share with females and young. However, there are many species where females obtain food to share and many others where females choose where to graze or otherwise get food. Clearly, males contributing to food gathering appeared late in our evolution and is related to attracting mates and pair bonding. My point is, females spent more time in the water gathering food and their success was critical to the survival of their young, so the loss of facial hair among females is more valuable to the species. On the other hand, males are much more violent than females. Consider that today the number one cause of death among US African-American males age 15 to 30 is other African American males aged 15 to 30. However, homicide is not a significant cause of death for US African-American females. When males fight the target is usually the face. Having a beard protects the face in two ways. It provides a small amount of direct cushioning and (because hair is somewhat slippery) tends to turn many blows into glancing blows. Many of the cuts that occur when shaven man fight are due to the shear forces created when the adversaries hand briefly sticks to the facial skin while the hand is still advancing. The best example of this today is among rugby players. Rugby is a very violent sport in which the participants do not wear helmets or padding. However, beards are very common among rugby players to cut down on their facial injuries. Again, with females doing most of the food gathering and males even having the option of stealing a portion from the females, the advantage of facial armor outweighs the disadvantage of slightly more drag when swimming.
http://aquatic-human-ancestor.org/anatomy/hair.html where AAT=Aquatic Ape Theory

Still, this might argue for fixed length hair (fur) which has the same advantages. Hair that grows to unchecked lengths (as it does on both human male and female heads) must have more advantage than simple deflection of blows.
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14
Physics, Astronomy & Cosmology / Re: How can we see ultraviolet light in Balmer series?
« on: 10/02/2022 08:40:20 »
Quote from: hamdani yusuf on 10/02/2022 02:39:20
Does anyone know how to derive Balmer series from Schrodinger's wave equation?
The internet knows.
https://chem.libretexts.org/Courses/University_of_California_Davis/UCD_Chem_107B%3A_Physical_Chemistry_for_Life_Scientists/Chapters/4%3A_Quantum_Theory/4.10%3A_The_Schr%C3%B6dinger_Wave_Equation_for_the_Hydrogen_Atom
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15
New Theories / Re: What is the new Intelligent Design?
« on: 07/02/2022 01:43:49 »
Quote from: MrIntelligentDesign on 06/02/2022 21:38:00
Do you mean that ToE is unfalsifiable?

No, I'm saying that you haven't falsified it.

Quote from: MrIntelligentDesign on 06/02/2022 21:38:00
Now, I will give you time here: what is your best falsification criteria for ToE to be falsified? And why you use that?

The discovery of a large number of out-of-order fossils (such as a pre-Cambrian rabbit) would definitely be a big problem for evolution to explain. The fact that there is a distinct chronological pattern to the fossil record is one of the big pieces of evidence for evolution. You start off with the simplest life forms (prokaryotes) which progress to single-celled eukaryotes then to colonial organisms like sponges, then simple invertebrates like worms, then fish, then amphibians, then reptiles, then mammals then humans. If there was no pattern to the fossil record, that would be evidence against evolution.

Biogeography is also evidence for evolution. The distribution of animals across the Earth's surface isn't random, but is related to what ancestors of those animals could have reached those places in a reasonable manner. From an evolutionary perspective, you'd never expect to find an African elephant on Easter Island, for example, because they would have no way to get there.

Genetic patterns are also strong evidence for evolution. The pattern of endogenous retroviral (ERV) elements (which were inserted by viral infections in the distant past) in chimpanzees and humans are extremely similar, which indicates that both chimpanzees and humans inherited these infection remnants from the same common ancestors. So another potential falsification would come from the discovery that two distantly-related animals (such as a gila monster and a great white shark) have significantly more ERVs in common than two closely-related animals do (a gila monster and beaded lizard).

Quote from: MrIntelligentDesign on 06/02/2022 21:38:35
They do not normally give  a fair fight.

What makes you say that?
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16
The Environment / Re: Is hydrogen a better fuel source for the environment?
« on: 06/02/2022 14:38:51 »
Quote from: alancalverd on 06/02/2022 10:18:38
Going back a few posts, I note that hydrogen has been declared  by an expert consensus uneconomic and unfeasible for domestic heating and urban transport. Precisely the uses for which it was put in every city 200 years ago, and currently in Orkney, respectively.

The right economic comparison is between making heat by burning hydrogen generated by electrolysis using carbon-free electricity, and using the electricity directly to make heat.  From a systems cost point of view, hydrogen loses in this comparison.   First, electrolysis is at best about 75% efficient in capturing the energy content of electricity.   So you need a lot more green electricity sources to make up for that loss.   Second, you need an essentially duplicative energy distribution grid to get the hydrogen to where the heat is needed.   The cost of that network raises again the cost of hydrogen relative to electricity.  Finally, hydrogen is substantially less efficient as a source of heat in a home or building.  A hydrogen fueled furnace is at best about 95% efficient in delivering the energy content of its fuel as heat; in all but the coldest climates, an electrically driven air-source heat pump can easily deliver 300% annualized efficiency (and in climates where there is any demand for summer cooling, the equipment for heating and cooling are essentially the same, so there is additional advantage there).

Over all, hydrogen from electrolysis loses the economic equation horribly as a domestic heat source.

Quote from: alancalverd on 06/02/2022 10:18:38
Fixed distance between termini means that you can start with just one or two refueling points, say London and Birmingham, with minimal environmental impact  and speeds of 200+ mph. Hydrogen power offers a compromise between the fuel weight of a diesel generator and the cost and engineering limitations of overhead power lines.

I agree on the value of high speed intercity trains.   Far superior to air travel for most, and maybe all travel on the island of Britain and in most of Europe.   When you figure in the ability of trains to move people city-center to city-center, I think the advantage is there for distances well over 200 miles.   I have no opinion on air-levitated trains, although the idea makes sense.   But trains, of all forms of transportation, most readily lend themselves to battery-electricity power.   Refueling is a matter of switching discharged battery trucks off the train, and full charged ones on, or for that matter, if you're building an air levitated system, building induction recharging coils into select track runs.   (In other words, I think the need for friction-contact overhead electrical lines is soon to pass).    The mass disadvantage of batteries for transport that you've assiduously plugged here simply are not present in "rail" based transport options.


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17
General Science / Re: What is Quantum Tunnelling and how does Quantum Tunnelling work?
« on: 01/02/2022 19:41:13 »
Hi again.

   So let's see if there are any questions left over from Aeris.

Quote from: Aeris on 29/01/2022 16:24:19
Let's say, hypothetically speaking, a macroscopic object like a table or a chair undergoes Quantum Tunneling and essentially teleports from one location to another while I'm still looking at it. What would that look like? would the object just pop right out of and then immediately back into existence in the blink of an eye?

    Let's just look at a microscopic objects for a moment (before we speculate and generalise to macroscopic objects).
We're going to consider the typical situation with a square barrier potential between two regions of exactly the same potential  (region I and region III).
    Here's the diagram again:


We're going to fire a particle toward the barrier (from region I) which has Energy, E < V0  exactly as before and we've already discussed the wave function and shown animated diagrams of this earlier.

    Firstly remember that the wave function is not the particle,  there isn't anything with properties like a particle until you go looking for it (make an observation to locate the particle).   The wave function just indicates the probability of finding the particle at a particular place.
   If you go back through the earier discussions and animated diagram you'll notice that the wave function isn't always 0 inside the barrier.   There is some time when the particle could be found there.

   Now this is where various sources of information (not just PopSci) are going to mess things up or mis-represent what seems to be shown by the mathematics.
   The amount of time over which the particle could be found "in the barrier" is controversial.   Some sources are going to tell you that it "instantly appears" on the other side of the barrier or just that "it will never be found in the barrier" etc.   I don't wish to use too much bad language but this is clearly utter bolderdash.

   Just go back and look at the animated diagram carefully if you want to, instead of doing the mathematics.   There are times when the real and imaginary components of the wave function are non-zero at a fixed x position inside the barrier.  So the square of the modulus of the wave function is not 0 at that time, this is the probability of finding the particle at that given point x in space and given time t.  I'm labouring the point here but we just need to be clear that the probability of finding the particle at that position x in the barrier is not 0 for some of the time.  The probability of finding of the particle in the barrier does not drop to 0 until some finite non-zero time has elapsed after the incident wave packet hit the barrier.   You will find many articles, some textbooks and countless discussions on Quora and similar websites that discuss qunatum tunneling as if it's instant.   Some of them are quite interesting and authoritative and discuss problems like the apparent breech of the speed of light   (If the particle could move from one side of a barrier of thickness, d>0, to the other side instantly than that is faster than light speed travel).   They're all good in their own way except that the fundamental premise they were based on was bollderdash.

    Anyway, the mathematics never implied that tunneling would be instant.

    Here's one article (from Scientific American) that describes an attempt to actually measure how long it takes a particle to tunnel through a barrier:
https://www.scientificamerican.com/article/quantum-tunneling-is-not-instantaneous-physicists-show/
   The details aren't too important, we just need to note that there may actually be some way of observing or measuring tunneling time in practice and it does not seem to be instantaneous.   It can be that the particle spends some time in the barrier.

   Anyway, we can now try to generalise this to a macroscopic scale:  Basically, there's no reason to assume that the quantum tunneling of your chair from region I to region III would be "instant".   It's not going to go "poof" from here and just "poof" into existance over there.  It is very likely to spend some time "in the barrier" between the two places.   I'm not sure what this would "look like" but it could be a lot less impressive than teleporting.   Given a piece of space between the start and end point (i.e. a piece of space in the barrier), then the chair could be found there for a short amount of time during the tunneling.   I really don't know how to paraphrase this, applying QM to macroscopic objects is always just going to be speculation anyway.   It might look like the chair was just moving from the start position to the end position and occupies at least some but possibly all of the positions between those two points in passing.  A whole lot less impressive than teleportation, I'm sorry to dissapoint you.

Another long, post, sorry.    In summary the only important thing is that Quantum Tunneling isn't instant and may not look like teleportation.

Best Wishes.

LATE EDITING:   I probably should make it clear that the time it takes for a particle to tunnel through a barrier is controversial.   This was stated originally but it's worth stating again.  You should probably make your own investigations.  Personally, I'm sticking to what the Mathematics shows.
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18
The Environment / Re: Is hydrogen a better fuel source for the environment?
« on: 23/01/2022 23:02:14 »
The Mirai is not really very competitive in fact, not being able to refuel at home is a complete show stopper for most people shopping for a green car:



The Mirai is selling very badly.
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19
The Environment / Re: Is hydrogen a better fuel source for the environment?
« on: 13/01/2022 20:17:22 »
Quote from: alancalverd on 11/01/2022 11:46:24
Hydrogen has 3 times the energy density of diesel fuel (roughly 150: 50 MJ/kg) and is the ideal liquid fuel in theory.

Hydrogen has 3 times the energy per mass as diesel fuel, but if you're actually talking about density, even compressed to 10,000PSI, hydrogen has about 1 quarter the energy per volume.   So, to get comparable range to what cars and light trucks now get with gasoline or diesel, you'd need a 200 liter tank.   And that tank will have to be cylindrical with semispherical ends, or spherical over all.   Think 55 gallon oil drum sized.   No fitting this in a flat space under the trunk or seats.

It's also basically a bomb if the vehicle is involved in a serious accident.   That 200 liters of hydrogen really wants to occupy 140,000 liters of space.    Lose structural integrity of the tank, and it will first blow apart through explosive decompression of the fuel, and then, more than likely, explode into a fireball.

I'm not saying those challenges can't be solved, but saying hydrogen is better than batteries for vehicles because "energy density" is both misleading, and leaving out some real challenges.

Quote from: Lewis Thomson on 11/01/2022 10:00:23
"Here in Australia there is a great debate about the pros and cons of hydrogen as a fuel source (fuel cells etc) versus electricity as a fuel source (batteries etc). I'd love to hear a detailed explanation and critique of hydrogen as a fuel source.."

You don't want to think of hydrogen as an energy source.   There simply isn't any source of hydrogen in it's reduced form accessible to us.    Hydrogen is an energy transmission and storage medium.   It fits between the source of energy, and it's end-use.

There are basically two energy sources that can be used to generate hydrogen that matter to the discussion.   You can create hydrogen by breaking down methane, using more methane as the heat source.   But that does nothing to decarbonize our energy system, and just creates a harder to manage fuel (hydrogen) out of an easier to manage one (methane).   It's a dead end. 

Or, you can generate hydrogen through electrolysis, with the electrical energy coming from renewable sources like wind or solar, or from other carbon-free sources like nuclear.    This is what most advocates of a hydrogen economy are imagining - basically, you still build all the renewable or carbon neutral electric generation capability we're talking about for the renewable future, but instead of moving the energy around in electric fields (wires) and storing it in batteries or other reverse generation technologies, you move it around in the form of compressed hydrogen gas, and store it as compressed hydrogen gas or liquid hydrogen.   Big parts of the fossil fuel infrastructure industry will advocate for this approach.   It keeps them busy building and operating wells (hydrogen plants), pipelines, and tanks.   It keeps transportation tied to roadside refueling (gas stations, literally this time around).   It feels like v.next of things they understand.   But it has little advantage to the electric infrastructure industry.   They may get to sell lots of electricity at commodity wholesale rates to the gas/liquid fuel industry, but it doesn't electrify the economy.

It doesn't benefit consumers particularly either.   Hydrogen won't be cheaper than electricity, since for all practical purposes, it is electricity transformed into chemical energy, before being transformed into heat or kinetic energy.   It won't re-use much of the infrastructure they own, since hydrogen cannot be efficiently utilized by their natural gas plumbing.   They will lose the advantage of being decoupled from roadside refueling for most of their transportation energy needs (electric personal cars and trucks will be fueled largely in their own garages, after all).   They get to keep rapid, roadside refueling, but more than a few will notice that the cost of that is that they are riding with a bomb the size of a 55 gallon oil drum in their trunk.

Nations need to answer the hydrogen economy question from a systems point of view - is the storage and delivery technology you get with hydrogen enough better than what you can get with batteries, at all scales, to justify the additional complexity?   It could be.   One can imagine Australia generating hydrogen in the 350 days of sun a year outback, and piping it to the populated areas, upgrading their infrastructure, and making all that work.  Personally, I doubt it.  I think there are better utility-scale energy storage options that hydrogen, electricity is a better distribution method, and batteries are good enough - and easier to get to - for transportation.

(There is a third way: you could crack methane with heat from nuclear reactors, to make hydrogen.  But you'd still be freeing fossil carbon, although not necessarily into the atmosphere - it could be a solid phase carbon with enough chemical engineering magic.   But you'd have to overcome your country's nuclear jitters.)
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20
Physics, Astronomy & Cosmology / Re: How can we see ultraviolet light in Balmer series?
« on: 02/01/2022 17:59:12 »
I think it is also important to note that the Balmer series (and Lyman, and Paschen etc.) are for atomic hydrogen, not molecular hydrogen (H vs H2). H is not stable at standard temperatures and pressures, but is stable at temperatures where electronically excited H atoms are thermally accessible.
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