I am Phil Plait, astronomer/author/blogger/some time TV host. AMA.

BadAstronomer · 29 days

How rare do you expect carbon planets to be compared to silicon rich ones?

Do you think such planets make good candidates for harbouring life?

SomeSillyQuestions · 3 months

If you blow the outer layers off a giant planet, you'll wind up with a not-particularly-large amount of matter sparsely distributed.

But would a substantial proportion of ejected particles settle on a stable orbit to form a ring of a gas around the star? Wouldn't most of the material fall into the star or get ejected from the stellar system altogether?

On the other hand, if you had a Neptune in your outer solar system, then it could potentially pick up a bunch of the blown-off material

Indeed, an interplanetary mass transfer seems more plausible. I wonder how much of the ejected material could, realistically, be trapped by the outer planets and incorporated into their composition.

WeRigMathTests · 3 months

Furthermore, there is this molecular trefoil for another example of a topological molecule

There is also a a molecular Borromean ring.

troopertrousers · 4 months

I once participated in an experiment where I briefly inhaled high concentrations (relative to air) of CO2. It is a very unpleasant experience

Can you provide more details? What made your experience so unpleasant?

SomeSillyQuestions · 4 months

An -R group can be pretty much anything

Are you sure about that? I always thought R stands minimally for an organic substituent.

R1 = O-

Yes, if R can stand for O-, that would make it a sulfonamide but as I said I have my doubts that is the case or else carboxylic acids would be considered ketones by taking R=OH.

SomeSillyQuestions · 4 months

It chemically contains a sulfonamide group.

Personally I don't see it.

Do you know what an -R group is?

Well it was a while since I studied chemistry but I hope so. It stands for an ~~alkyl group~~ organic substituent, right? If that's the case, and I think it is, I don't see how phenylsulfamate could be considered a sulfonamide.

Edit:spelling.

SomeSillyQuestions · 4 months

The second hit on googling "sodium phenylsulfamate" is Synthesis and taste properties of sodium monosubstituted phenylsulfamates

I can only read the abstract of that paper but they did actually test sodium N-phenylsulfamate or only some of its derivatives? ~~Anyway, according to this it does taste sweet but it has been also studied in animal models for its carcinogenic potential.~~ Sorry, that was cyclamate but according to this you're right, it only has a sweet aftertaste. I'm wondering why the substitution of a cyclohexane ring with a benzene one can cause such dramatic effects.

I know you were thinking that since we know the sweet receptor structure, and we have some things that bind weakly to it, why can't we just predict the perfect structure to make the perfect sugar substitute?

Well, not exactly, I was just curious to find out how would the substitution of the cyclohexane ring in sodium cyclamate with a benzene one alter taste perception but your question is a better one.

Edit:typos.

SomeSillyQuestions · 4 months

I don't think phenylsulfamate is a sulfonamide.

paintedsaint · 4 months

If we had infinite wisdom and ability I am sure we could create a form of life using a inorganic polymer perhaps even with Boron and solvents other than water

Indeed, it seems to me if I were to take the monumental task of designing a non-carbon-based lifeform from scratch a polymer consisting of alternating boron and nitrogen (or even phosphorus) atoms would be a good place to start, primarily because such building units seems to have the potential to emulate some of the behaviour seen in carbon including aromaticity but also because it would be interesting to see if it's possible to exploit the propensity of boranes to readily form polyhedral structures, something that is not seen in hydrocarbons. Intriguingly, this alternative biochemistry seems to work well with ammonia as a solvent, not only because boron-nitrogen derivatives have an affinity for ammonia as a solvent but also because, on average, such compounds are more reactive than their carbon counterparts so, apparently, this type of biochemistry is more feasible within the lower temperatures at which ammonia is a liquid. Thus, I wouldn't be too surprised if this exotic hypothetical biochemistry would hold an advantage over a more conventional carbon-based one on a cold ammonia rich planet.

I am not confident that such life would be common in the universe given the distribution and relative abundances of the elements.

Neither do I, the low cosmic prevalence of boron seems to be one of the strongest arguments against boron-based lifeforms being a frequent occurence in the universe but on the other hand there can be planetary positive feedback loops that could increase boron concentration in the upper layers of the crust. Also, if we look at Earth, life here is not based on the more abundant silicon but carbon which even though is the fourth most common element in Universe is relatively rare in Earth's crust. Keeping all these thing in mind I would be less surprised by the discovery of a boron-based organism than that of a silicon-based one. Anyway it's pretty fun to speculate about boron-based lifeforms living in the proximity of boron hotspots in the same manner nonphotosynthetic organisms live near hydrothermal vents on Earth on a otherwise boron poor ice planet.

Edit:spelling.

paintedsaint · 4 months

I remember seeing a comment somewhere that boron's chemistry may be as interesting and varied as carbon - or even more so - but that it's rarity causes it to be much less explored. Any truth to that?

Was it this one? or maybe this one?

paintedsaint · 4 months

It lacks the ability to easily make long chains such as Carbon

Well, it can certainly give rise to some pretty complex structures and some long chains too, at least in conjunction with nitrogen.

The main lacking feature other elements all fail at is playing the role of a building block. Carbon is the lego of the atomic world and you can build structure and hold shape with it.

How about using two building blocks instead of one as seen in inorganic alternating copolymers?

only carbon abundant molecules get the job done.

I'm not so sure it's as clear-cut as you claim it to be.

This is the same reason most if not all plastics are repeating carbon units. You just can't get that kind of versatility anywhere else.

Inorganic polymers aren't unheard of.

madhatt · 4 months

Sorry, the emperor penguin could be a good food source

As the biggest penguin that was my impression too but I thought you claimed otherwise.

this penguin species is found in Antarctica year round

I think it's important to mention that they disperse into the oceans from January to March.

Especially in winter when penguins are dispersed in the southern waters for feeding.

I think you contradict yourself. Wouldn't that be the Antarctic summer?

madhatt · 4 months

Of course assuming you transferred the polar bears to areas with penguin colonies they would have pretty good (but seasonal) food source - unless it is the Emperor which winters in Antarctica.

I don't understand why the Emperor penguin is an exception, why isn't it a good food source? Can you elaborate further?

SomeSillyQuestions · 4 months

Depends on how you define metallic

Indeed, is partially also a semantic issue.

with some imagination you can imagine any element having some densely packed phase that exhibits these properties.

So when, for example, the qualifier metallic is applied to hydrogen is it meant in a relative or absolute sense? Would hydrogen be considered a metal if it displayed those properties at standard room temperature and pressure?

SomeSillyQuestions · 4 months

In this case, the substitution of the hydroxyl group with the chlorine makes it bind to the receptors more strongly.

Does that happen in a predictable fashion? Would a more aggresive chlorination of sucrose that replaces more of the hydroxyl groups result in an even sweeter compound?

SomeSillyQuestions · 4 months

I believe it's essentially matter of low bioavailability.

So do you think its low bioavailability fully explains its low toxicity?

SomeSillyQuestions

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