1

Chemistry / Can single bonds be pi bonds?

« on: 10/09/2019 18:50:03 »

I teach chemistry at both the undergraduate and graduate levels (and general public level as well occasionally), so I am no stranger to explaining the same phenomena in different ways that are not necessarily in good agreement (undergraduate level often being oversimplified dramatically for ease of understanding). But every so often I find myself trying to figure out whether undergraduate "facts" are valid and hold up to scrutiny of more complex models... this is one of those times.

Undergraduate level understanding of single and multiple bonds:
• A single bond is always a sigma bond, while a double bond is one sigma bond and one pi bond, and a triple bond is one sigma bond and two pi bonds.
• This explains why single bonds are free to rotate while double bonds cannot (rotating a bond with pi symmetry would require breaking the bond.)

Screen Shot 2019-09-10 at 1.41.35 PM.png (134.37 kB . 1116x698 - viewed 165 times)

Advanced level:
• We have to look at the molecular orbitals to accurately describe the electronic structure.
• For example, the molecular orbital diagram of B₂ predicts a Bond Order of 1 (4 electrons in bonding orbitals and 2 electrons in antibonding orbitals) And because the filled sigma bonding and filled sigma antibonding orbitals cancel, and the unbalanced bonding electrons are in pi bonding orbitals, the single bond must be a pi bond.


Screen Shot 2019-09-10 at 1.43.20 PM.png (26.87 kB . 332x720 - viewed 159 times)

What I'm struggling with now, is trying to think if there is some actual experimentally verifiable consequence of this (like restricted bond rotation). Unfortunately, bond rotation is meaningless for the linear B₂ molecule, but perhaps someone who hasn't been overthinking this can suggest another molecule that appears to have a single bond with pi symmetry, and would have other bonds that could be used to define rotations.

Other probing questions welcome--anything to break myself out of this current and useless perspective... thanks!

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Physics, Astronomy & Cosmology / Could LIGO "see" alien warp technology?

« on: 01/09/2019 20:22:23 »

If there were aliens capable of using a "warp" drive (like an alcubierre drive, or star trek, etc.), how "big" would it have to be for LIGO to see (let's assume it's in our galaxy)? What about on the Earth? (we could see if anyone had successfully tested such a thing)

What would the signal look like?

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Physics, Astronomy & Cosmology / MOVED: Do you think sports is sciencee?

« on: 26/06/2019 18:32:32 »

This thread can now be found in the "Just Chat" subforum: https://www.thenakedscientists.com/forum/index.php?topic=77243.0

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Chemistry / why do phosphines and isonitriles smell so bad, while CO is odorless?

« on: 10/06/2019 22:45:07 »

I’m not sure which section this goes in (could also be physiology or biology).

Why is it that we have such a strong visceral reaction to the smell of compounds like primary phosphines, even at very trace levels? (some have odor thresholds below 1 ppb) They are toxic by inhalation at the ppm level, but I don’t think our ancestors would ever have had the pleasure of smelling such compounds. Sulfides, sure, but phosphines? The perception of these compounds by smell could be  very similar (sulfides and phosphines are chemically similar), but why are they sooo bad?

Also, isonitriles are similarly wretched-smelling, but the analogous carbon monoxide (which is chemically fairly similar) is completely odorless. And I am quite confident that our ancestors came into quite a bit of contact with carbon monoxide while they were working out the whole fire thing.

It is all quite curious…

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Physics, Astronomy & Cosmology / MOVED: How do we measure the energy of a photon?

« on: 30/03/2019 19:03:06 »

What initially appeared to be an interesting question regarding quantum epistemology has turned out to be (or transformed along the way into) the original poster trying to proselytize a new theory that is outside generally accepted science--thus I have moved the entire thread to the "New Theories" section, where this discussion may continue.

You may find it here: https://www.thenakedscientists.com/forum/index.php?topic=75960.0

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General Science / I can haz complete list of Realz?

« on: 05/03/2019 19:30:14 »

Hello!

I am interested in knowing how many different types of numberz there are. Please provide a complete list.

7

Just Chat! / What does Russia do after Putin?

« on: 04/03/2019 19:17:26 »

Vladimir Putin has been the leader (de facto and official) of Russia since 1999. As I understand it, he solidified his image by dramatically improving life for Russians after Yeltsin, and he now maintains a very tight grip on Russian politics and money by keeping the wealthiest Russians (oligarchs) happy enough, keeping other aspiring politicians down, ruthlessly attacking media and opposition groups at home and abroad, and keeping the general population distracted.

But Putin (as far as I know) is mortal, and if the wikipedia page can be trusted (big IF, I know), he is only 5 years away from the expected lifetime of Russians (Putin is 66.5 years old, and life expectancy in Russia is only 71.5 years!). Of course as an ultra-wealthy and very powerful man, he probably has much longer than that, but somehow I doubt there will be more than another decade of Putin in power (his term officially ends in 2024). Having so few other major politicians, how does succession look for Russia?

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Physics, Astronomy & Cosmology / MOVED: Is my Theory Of Gravitational Field valid?

« on: 12/02/2019 16:54:23 »

Please find this new theory posted in the New Theories section of the forum: https://www.thenakedscientists.com/forum/index.php?topic=76176.0

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Physics, Astronomy & Cosmology / Moved: Photoelectric effect as resonance phenomena?

« on: 30/01/2019 14:48:03 »

This New Theory has been moved to the New Theories subforum:
https://www.thenakedscientists.com/forum/index.php?topic=75994.0

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Physics, Astronomy & Cosmology / Moved: he intriguing gsas and dust ennveloping black hole is SOLVED.

« on: 30/01/2019 14:45:33 »

This New Theory has been moved to the New Theories subforum: https://www.thenakedscientists.com/forum/index.php?topic=76026.0

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General Science / Are there aliens made of lava?

« on: 14/01/2019 14:56:47 »

I'm not sure where to put this (and I wouldn't be offended if this thread were moved to New Theories). I recently watched an excellent youtube video about Saturn's moon, Titan:

I realized that we would be “lava aliens” on Titan—where cryo-volcanoes release liquid water (with dissolved species, like salts and ammonia), which freezes back into ice at the surface, creating domes and other geological features almost completely analogous to our own volcano-dominated landscapes. Our body temp would certainly be high enough to boil their lakes (liquid methane and ethane) and melt some of their "rocks" (many of which are composed of water ice or heavy hydrocarbons, like benzene). We would need to bundle up to keep ourselves from freezing to death.

Likewise, we could imagine molten silicate-based life forms, from much hotter places (maybe even inside the earth???) which would need to bundle up quite warm to keep from freezing to death on our surface. They would instantly boil water, and could melt our rocks. Would they consume lava from volcanoes as we would water from cryo-volcanoes on Titan?

Many have previously discussed the possibility of silicon-based life, some recognizing that higher temps might be involved.

I wonder what sort of chemistry would be involved in such life forms...

12

Physics, Astronomy & Cosmology / Could Oumuamua be a light sail?

« on: 06/11/2018 15:05:15 »

Remember Oumuamua? (that interstellar thing that whizzed by us in 2017?) They're not saying it's aliens... (please be aliens! ...maybe?) but they are saying it is consistent with a light sail. (and "they" includes the chair of the astronomy department at Harvard)
https://arxiv.org/pdf/1810.11490.pdf

Part of the evidence is a previously published result that shows non-gravitational acceleration away from the sun with a statistical significance of 30 sigma (that's very high)
https://www.nature.com/articles/s41586-018-0254-4

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Physiology & Medicine / Moved: Hpv is only sexually transmitted. This is a neurological disease and not

« on: 01/10/2018 19:10:50 »

I have taken the liberty of moving the thread, "Hpv is only sexually transmitted. This is a neurological disease and not a vener" to the New Theories section of the forum. It can be found here:

https://www.thenakedscientists.com/forum/index.php?topic=74976.0

I would like to reiterate that most of the sections of this forum are reserved for discussions of generally accepted science, and are not suitable for threads that focus on selling new theories that run contrary to generally accepted science. Threads that do focus on selling new theories that run contrary to generally accepted science belong in the "New Theories" or "That CAN'T be true" sections.

Thank you.

14

Physiology & Medicine / Moved: Can cancers be treated by burning them with a hot probe?

« on: 29/09/2018 18:47:22 »

I have taken the liberty of moving the thread: Can cancers be treated by burning them with a hot probe? to the New Theories section of the forum. It can be found here: https://www.thenakedscientists.com/forum/index.php?topic=74771.0

I would like to reiterate that most of the sections of this forum are reserved for discussions of generally accepted science, and are not suitable for threads that focus on selling new theories that run contrary to generally accepted science. Threads that do focus on selling new theories that run contrary to generally accepted science belong in the "New Theories" or "That CAN'T be true" sections.

Thank you.

15

Physics, Astronomy & Cosmology / Moved: Why do protons not decay?

« on: 25/08/2018 16:51:47 »

This thread appears not really to be a question about protons decaying, and more of a case for a new theory of matter-antimatter asymmetry. Thus, it has been moved to the New Theories sub-forum, and can be found here: https://www.thenakedscientists.com/forum/index.php?topic=74586.0

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That CAN'T be true! / Is yuno44907 really banned?

« on: 29/05/2018 01:24:06 »

Yes, yuno44907 has been banned, and the thread started by this former member has been moved to the recycle bin. Apologies to those members who did spend time responding to the posts within this thread, they are also in the recycle bin (if you feel strongly about having the text of those messages, PM me, and I can send it your way). And apologies as well to anyone else who spent any time reading the posts of yuno44907... we gave him a chance, and it was squandered.

17

Chemistry / How toxic is cinnabar (vermillion)?

« on: 05/05/2018 14:09:31 »

Cinnabar is a beautiful naturally-occurring mineral composed of mercuric sulfide (HgS). There are many examples of jewelry, statues, and even plates made of the stuff, but a quick online search also reveals many pages warning of its unparalleled toxicity (and nearly as many talking about its "crystal healing properties"--ugh I hate that pseudoscience! but I digress...). The only material safety data sheets I have come across do not list any LD50 data. The question is, is cinnabar actually really toxic, or are people just assuming that it is because of the mercury content?

I am well aware of the toxicity of elemental mercury, organometallic mercury compounds, and water-soluble mercury salts, but I also know that actual toxicity is a function of both inherent toxicity and bioavailability. HgS is one of the most water-insoluble compounds: its K_sp is on the order of 10^–54, meaning that a saturated solution in water would only contain about one or two mercury atoms per liter!! And other resources indicate that it will only react with very strong acids to produce soluble species (I wouldn't want to eat it).

Industrially, the compound is roasted to produce sulfur oxides and elemental mercury. So is the toxicity of the mineral due to slow oxidation in the air, leading to production of Hg metal?

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Physics, Astronomy & Cosmology / How fundamental is time?

« on: 01/05/2018 17:50:19 »

Please note: This thread may sit on the edge of generally accepted science and speculation. I would like to keep it in this sub-forum (which is intended for discussions of generally accepted science), so let us agree to be clear about when we are speculating/hypothesizing.  Thanks! (also note: While I personally have a fairly advanced understanding of QM, I have only a modest understanding of general relativity, so please bear with me, and know that I am here to learn)

~~~~

Time is simultaneously (sorry) a simple concept and a difficult one to grasp. Clearly, our perception (as human beings) of time is not entirely quantitative. There are many different biological and psychological aspects of our perception that I do not want to delve in to. Rather, I would like to discuss purely physical and mathematical interpretations of time.

I have had many questions about time swirling in my head for a while now, and I think I can distill them into two primary questions:

(1) Is time the most fundamental "temporal" dimension, or is it a function of an unrecognized dimension?
This question comes about when trying to conceive of an absolute time scale. Every equation I have come across in my education in the physical sciences deals with dt or Δt, and so is really just dealing with relative time (t = 0 is arbitrary or internally defined, and any indefinite ∫f(t)dt will have that pesky "+ c" term).

Many people point to the Big Bang as the natural t = 0, but this raises at least as many problems as it addresses.

So is time a function of another more fundamental parameter t = G(α), and most of our equations are actually only valid for α, but are comfortably within experimental error of t?

For example let us imagine that α = t +ln(t)/t (unfortunately, there is no algebraic solution for the inverse, but we can solve it graphically, just by swapping the α and t axes--it would be nice if someone can recommend a function that has similar properties but can be explicitly solved both ways):

Screen Shot 2018-05-01 at 12.11.47 PM.png (36.26 kB . 570x563 - viewed 3592 times)

(If we look at the blue curve pictured above, and consider the abscissa as the α axis and the ordinate is the t axis)
Clearly, consideration of t ≤ 0 gives only nonsensical results, but the function is well-defined for all values of α, and for large positive values of α (or t), α ≈ t. For example, t = 1000 returns α = 1000.006908 (an error of about 7 ppm), and for t = 10¹⁰ the error is only 2.3×10^–19, well beyond the temporal precision of any experiment I know of. And the convergence of dα and dt (or Δα and Δt) will come even faster.

This relation has the obvious shortcoming that it requires some explicit definition of the unit (you will get different answers using years, seconds, or any other arbitrary unit) ie we have traded the problem of an absolute zero for the problem of an absolute 1. Perhaps there may be a fundamental unit of time (and therefore a fundamental unit of space, based on the relationship defined by the speed of light)?

However, this may obviate some of the difficulties that come when considering inflation (the big bang type, and perhaps what we see now). How could we experimentally (or theoretically) test the validity of this type of model?

(2) Are there different "kinds" of time?
Just as there is inertial mass and gravitational mass, which are conceptually different, but appear to be the same, for reasons which (to the best of my knowledge) still elude us. Are there conceptually independent "kinds" of time?

19

Physiology & Medicine / MOVED: What is psychoenergetics research?

« on: 02/03/2018 20:53:28 »

This thread is now in the New Thoeries Section
https://www.thenakedscientists.com/forum/index.php?topic=72487.0

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Chemistry / Does one invent or discover new synthetic compounds?

« on: 28/02/2018 18:00:32 »

This may be just an issue of semantics, but it has come up again in conversation recently, and I wanted to see what others think.

I think most would agree that when a chemist who isolates a previously undescribed natural product from a sea slug, this is an act of discovery. The compound already existed, and has been produced (or harvested) and used by these creatures for likely several millennia, at least.

But what about when a chemist performs a chemical reaction in the laboratory, creating a previously undescribed synthetic compound. For the most compelling argument in favor of "invention," let us say that the structure of the compound was specifically chosen (designed) for a particular purpose, and that this compound was then intentionally made. Furthermore the molecule is sufficiently complex and distinct from naturally occurring motifs that it is highly unlikely that the compound had ever existed before in the observable universe (it can be calculated that for even modestly sized molecules made from only a handful of elements, there are so many possible stable structures that there isn't enough matter in the observable universe to make a single molecule of each--not by several orders of magnitude!)

If this most stringent definition is not enough to claim "invention," why not?

And if it is, does it cease to be an invention if the compound had been intentionally made before? What about just naturally produced somehow? Or if it was not actually the intended product (if a new compound is made by accident, does it still count?)