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General Science / Re: Do Ice Cubes Melt Faster In Fizzy Drinks Than Still Drinks?

« on: 28/07/2020 22:06:38 »

Could also be that some CO2 dissolves in the ice and lowers its freezing point. You might try some properly controlled experiments with, say, Sancerre and champagne, or bottled versus draught Abbott Ale, but don't waste valuable lab time with water.

Do you need volunteers for the experiments?

But more seriously, the bubbles may act to roughen up the surface of the ice cubes creating more surface area and faster melting.

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Physics, Astronomy & Cosmology / Re: How Did Time Come Into Existence ?

« on: 26/07/2020 19:13:51 »

, or somebody being her own mother.
*resists urge to link to I'm my own grandpa song*

Being already embroiled in several other threads and trying to find the time to create another, I will restrict my comments at this time to noting that the song I'm my own grandpa plays on the jukebox in Heinlein’s short story All You Zombies. This story concerns a gender changing time traveler who is her/his own parents.

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Guest Book / Re: Are there rules on reviving old threads?

« on: 17/07/2020 17:12:26 »

Is it legitimate to post on this thread quoting posts that old?

As @Bored chemist says, it’ Ok if you are adding something. @Monox D. I-Fly does it all the time, although maybe not adding value every time.
It is, however, a technique used by trolls  and spammers to get their post count up, easily spotted because the posts are usually inane.

Well, I did it. Hopefully it is not considered spam category.
https://www.thenakedscientists.com/forum/index.php?topic=7801.msg608751#msg608751

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Chemistry / Re: What is the difference between an "atomic" and a "nuclear" bomb?

« on: 17/07/2020 17:03:45 »

Necromancy at work here. But I was advised that this was OK if I have something meaningful to say. Which I do. (I hope)

there is however a limited size you can make this as the bomb tends to blow itself apart before it has all ignited.

Yep. I believe only about 4% of a simple Uranium or Plutonium bomb is fissioned before the bomb had undergone 'self-disassembly'...

Practical efficiency of a fission bomb is about 25% but is usually less. The Fat Man plutonium bomb used on Nagasaki had an efficiency of about 17%. The Little Boy uranium bomb used on Hiroshima was very inefficient and had an efficiency of about 1.4%.

The much greater efficiency of Fat Man was due to:

@ The use of plutonium, with its much higher spontaneous fission rate

@ The faster assembly and greater compression of the implosion design versus the Little Boy gun design

@ The natural uranium (unseparated isotopes) tamper that helped slow the expansion of the plutonium undergoing fission, increasing efficiency, and by absorbing neutrons, converting some of the U-238 to Pu-239 (or even fast fissioning Pu-240) which then underwent fission when more neutrons were absorbed, along with the small U-235 component.

Before developing the true hydrogen bomb, there was the boosted fission design that added lithium 7 deuteride to the stew. The lighter atoms helped slow down the neutrons that were flying around to make them more readily absorbed by the plutonium. In addition, lithium is a rare case of a nucleus sensitive to high temperate (about 100,000 K) then breaking up into 2 atoms of tritium and a neutron. Some of the tritium and deuterium will undergo fusion releasing some energy and more neutrons. All these extra neutrons will lead to more plutonium undergoing fission, boosting yield.

Fusion bombs only work at very high temperature conditions, so generally use the x-rays released by a fission explosion to give conditions for 'ignition'. The bigger bombs have a layer of fissionable material outside the fusion bomb to increase the yield so you get a fission->fusion->fission explosion. Not sure if the biggest bomb dropped in the atmosphere (Soviets, 47Megatonnes TNT-equivalent) was this type or not but if gives you a feel for it - 3000 times the 15 kilotonnes explosion at Hiroshima.

The natural uranium tamper used in three stage nuclear weapons works on the principles described above, which also apply to fusion processes.  The Soviet RDS-220 Tsar Bomba used lead in the third stage tamper. Uranium has a density 80% greater than lead so the tamping was less efficient. The point of using lead was that a uranium tamper in a device this size would have increased yield to about 100 MT but created enormous quantities of fallout over populated areas. Since the actual yield was almost exclusively from fusion, this was in fact a very clean event in terms of fallout.

The explosive yield was originally estimated by Western experts as 58 MT based on seismic data. Many years later, after the breakup of the Soviet Union, Russian scientists released a figure of 50 MT. This was a truly gigantic explosion and the mushroom cloud shape was readily visible 160 km away, having risen to a height of 65 km.

Hard to understand why anyone would want or need an explosion that big...?

The main purpose was clearly propaganda, intended to intimidate new US president Kennedy, who had earlier that year (1961) attempted an invasion of Cuba, then a recent addition to the ranks of Soviet allies.

The Soviets were interested in very high yield devices not as city busters as might be thought but to be used against US Strategic Air Command wartime HQ under 3000 meter tall Cheyenne Mountain in the Colorado Rockies. Construction had been initiated by President Kennedy early in 1961. SAC controlled the B-47 and B-52 bomber fleets and US ICBMs.

The Tsar Bomba weighed 27,000 kg and could only be carried by a modified Tu-95 ‘Bear’ turboprop bomber with some of its fuel tanks removed to make room. This was clearly not a viable delivery system. However, years later a 28 MT warhead was developed for the Soviet R-16 ICBM (NATO reporting name SS-18 Satan).  This missile was capable of delivering its payload anywhere in the world. A warhead of this size would make a crater over 300 meters deep in solid rock and send a gigantic seismic wave through the mountain.

Consider that Hiroshima was in the mid to end 1940's, this Soviet bomb was  at least 20 years after that. Now consider that its been aproxomatly 40 years since the Soviet bomb, thats double the time it took the to make a bomb 3000 times the size of hiroshima, imagine a bomb 6000 the times of the soviet bomb, thats what we could have now but we wont ever see the explosion of one of those bombs unless it is used in a war because most countries including the united states and the former USSR.

The Tsar Bomba was detonated on October 30, 1961, a little over 16 years after Hiroshima. It remains the most powerful nuclear device ever made. Technology has concentrated on smaller and lighter weapons, on tactical weapons and on specialty devices like neutron bombs and focused microwave emitters intended to fry electronics.

Also in response to the why would you need such a large bomb question, the Soviets spent their resources making bigger bombs whereas the united states used their money to make accurate bombs, basically the soviets were going under the possibility of why guide a bomb to one house you needed destroyed if you could blow up the whole city and be done with it

In the 1950s, the US concentrated on making nuclear weapons smaller and lighter so that they could be carried by missiles. The Soviet Union concentrated on making bigger missiles. Targeting weapons against objects the size of a house from great distances did not really become feasible until the 1980s and then in cruise missiles, not ballistic ones. The GPS guided strategic version of the Tomahawk jet powered missile could be launched from a submerged submarine off the coast of New York City and hit a garage door in Chicago.

population of Hiroshima, and certainly none of any military significance.

I understand that Nagasaki was a military port, but the mountainous terrain limited the damage done by a single bomb.

Hiroshima was not a significant military target, but its flat terrain and large population turned it into a nuclear target.

Hiroshima had a large Army depot and an active port. Nagasaki was a major producer of naval ordnance and had a port used by the Japanese Navy. However, by that time Japan no longer had a Navy to speak of. But a major consideration of target choice was impact on civilian populations. Tokyo was no longer worth bombing, having 70% of it already burned to the ground by B-29 fire bombing, no military value anymore and mostly abandoned.

Here is an interesting article on how the nuclear bombing targets were chosen.
https://www.theatlantic.com/international/archive/2015/08/hiroshima-nagasaki-atomic-bomb-anniversary/400448/

Interestingly, one of the selection factors put forth in early May 1945 was that a proposed target was “likely to be unattacked by next August”. Anyone know why August was significant?

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New Theories / Re: If there was one Big Bang event, why not multiple big bangs?

« on: 13/07/2020 20:29:11 »

Tell me more details about the whacky action of mesons; I am interested to know more about science discoveries related to various views about the universe.

I have been busy with both RL and with other threads here and have not gotten around to writing a clear exposition of my ideas mentioned above. Plus in replying to another thread, the one about the B Meson, I realized that I need to do some research and correct the math.

In the meantime, check this out.

http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html

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New Theories / Re: What is a photon ?

« on: 13/07/2020 17:04:58 »

What physical experiment could be performed to demonstrate that particles are Riemann spheres?

Orientate an Electron such that it's axis (pointing from the point 0 to the point ∞) points in the "up" direction. Then it will not emit a photon in the "down" direction.

Also: particles seen from their northern hemispheres will look different as seen from their southern hemispheres.

Wrong. The direction of photon emission when an electron drops from excited state to ground state is random with respect to the electron's spin state, which is the only way of talking about an electron’s axis.  The direction of photon emission is determined in a probabilistic manner by multiple factors including the prevailing magnetic field, of which the nearby nucleus is a major component, and preserving energy momentum conservation over event accumulation.

In addition, electron spin is a matter of angular momentum, in effect spinning clockwise or counterclockwise. It is not a matter of which way a pole is pointing. Electrons with opposing spin values are not ‘upside down’ with respect to each other. They are spinning in opposite directions. To drive that home, the only formulation for spin states that matches measurements is the formalism of angular momentum.  For that to be the case, the clockwise or counterclockwise spin must be with respect to a fixed axis. That is, your hypothetical 0 and ∞ axis must always point in the same direction, negating your argument.

Now explain what differences there may be between the two hemispheres of an electron. Oceans, continents, ice caps? Your insistence that the metrics of a Riemann sphere are those of an ordinary sphere and not the varying metrics of a complex plane mapping argues against any difference.

Also, since the question Kryptid asked is about a physical experiment, how would you determine which photon came from which electron and how to determine the axis orientation of the individual electrons?

So what does “communicated between fields (plural)” mean?

Think of the Feynman diagram of an electron scattering off an electron. What happens is: one electron must tell the electromagnetic field that it wants to scatter of another electron following a path λ, and it must specify its momentum. This must be read off the electron field interacting with spacetime. Then the electron must specify it's expected momentum change. Then the electromagnetic field must compute the virtual photon direction and wavelength and the positions for invoking the creation and annihilation operators, then the virtual photon must communicate the change of direction of momentum to the other electron. Only then can the virtual photon be emitted.

Wow, where do I start?

To begin with, you are using two different meanings of the term ‘field’. Originally you used the term with respect to a particle being a ‘vibration’ in a field, which would imply field theory, a field being a mathematical apparatus for determining the properties at any given point. Now you are using the term to refer to the electromagnetic fields of electrons. Same word, different meanings.

The term λ (lambda) does not appear in Feynman diagrams. That term is used in General Relativity for the Cosmological Constant. What does appear in Feynman diagrams is the term γ (gamma), which is the symbol for the photon. In Feynman diagrams, it is the label applied to the wavy line that indicates the exchange of virtual photons. This diagram show electron-electron scattering.



In Quantum ElectroDynamics (QED) for which Feynman diagrams were first invented, the path is not first chosen. In theory, any path at all might be used, each having its own probability amplitude. This is a wavelike entity. As such, probability amplitudes constructively and destructively interfere with each other. The effective path is the one with the greatest surviving probability amplitude, and usually the only survivor with a resulting probability (square modulus of amplitude) of unity. Paths happen. They are not chosen. There are experiments demonstrating multiple paths being used such as the famous double-slit example.


There are people here who are familiar with deep Physics and deep Mathematics. You cannot make it up as you go along and not get called out.

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New Theories / Re: If there was one Big Bang event, why not multiple big bangs?

« on: 08/07/2020 23:08:30 »

if the universe is infinite in space, time, and energy, none of those three characteristics can be bounded. I remain open to any logical ideas.

Bounded is not the operative word. The surface of a sphere is finite yet unbounded. No edge to fall off. A universe that is a 4-dimensional hypersphere would also have no bounds but still be finite. Since time and energy are contents of the universe, they would be finite but have no edges, no bounds.