1

Chemistry / Re: Apart from colour, what's the difference between white and brown sugar?

« on: 18/10/2019 17:59:06 »

I doubt there is any significant difference in "healthiness." Both are essentially sucrose. Brown sugar usually also has some monosaccharides (glucose and fructose) and some very minor impurities that add some color and more complex flavor (as well as traces of vitamins and minerals, but not likely to be dietarily useful at healthy doses of sugar). White sugar is just a little bit purer, and is also often bleached (making the impurities less dark, not necessarily less of them).

2

Question of the Week / Re: QotW - 19.10.14 - Are most animals edible? Would the dinosaurs be edible?

« on: 14/10/2019 18:55:58 »

Cooking can turn many inedible things into at least somewhat edible foods.

But we probably wouldn't even need that to eat dinosaurs (though it would be much tastier cooked). Since we can eat most reptiles (lizards, snakes, turtles etc.), which branched off before the dinos, and we can eat most birds (chicken, pigeon, duck, emu, etc.), which evolved from dinosaurs, I would say its a safe bet we could eat dinosaur meat.

3

Chemistry / Re: How to convert kDa to molecular weight?

« on: 13/10/2019 22:37:27 »

They are both right. Cholesterol is a small molecule with a molecular mass of 387 g/mol (or387 Da). And many proteins have molecular weights of hundreds of kg/mol (KDa)

4

Plant Sciences, Zoology & Evolution / Re: What is the shape of one's family tree considering only ancestors?

« on: 08/10/2019 18:39:34 »

Well... I doubt there is any validity to the "Adam and Eve" scenario.

As I understand it, the emergence of a new species is not usually because there are two mutants of one species that happen to be different enough to be its own species, and then they go off together and start their own species.

Instead, there are populations that are isolated from each other and then over the course of many generations, the natural mutations and different selective pressures can cause some differentiation between the populations. If this goes on long enough, the two can become genetically incompatible, and then we define them as different species.

We can see a little bit of this when considering differences between people today: https://en.wikipedia.org/wiki/Recent_human_evolution

There appears to be evidence that hominids interbred multiple times before homo sapiens wiped out the rest--some folks today have some neanderthal genes!

Back to the shape of the tree...
I think you may also be surprised by how many of those branches come back in. While we consider relationships between siblings (sharing both parents) or between half siblings (sharing one parent) to be incestuous today, I'm sure it happened historically to some extent. More common (and still acceptable in some places today) are relationships between cousins (sharing one set of grandparents), and this was more more common a long time ago (especially in very small and isolated populations). The longer ago we consider, the less mobile people were and the smaller the population, so there are sure to be many instances of couples who share at least one pair of great-great grandparents (even this might not raise many eyebrows today).

Of course, the tree also has lots of dead ends. War, diseases, calamity, genocide, and predation were all much more common ways to die a long time ago, and often would strike before genes were passed on.

5

The Environment / Re: Why do clouds stay high up when they are heavier than air?

« on: 08/10/2019 17:08:17 »

Is a cloud gaseous water or condensed water?

yes

A cloud is not an object in the traditional sense. It is a region of the atmosphere in which conditions are right for water to be in equilibrium between gas and liquid (and solid). The gas is lighter than air, and the liquid is heavier (but small droplets can remain suspended as an aerosol).

The boundary of the cloud is not a true edge: water is going in and out of the cloud all the time. But only within the region of the cloud is the aerosol stable. Any water outside of the cloud is either in the gaseous state, or is precipitations (solid or liquid).

6

Physics, Astronomy & Cosmology / Re: What is the weakest sound that can be detected?

« on: 07/10/2019 20:57:20 »

Thanks but I didn't say by human ear.

Ok, then I think the most sensitive detectors we have for vibrations are those that are looking for gravitational waves (LIGA and VIRGO), which can detect minuscule vibrations. (I can't find the numbers now, and gotta run--but I will say that they are the equivalent of using a seismometer to hear a mouse fart on the other side of the globe.)

Found it: One example is 10⁴⁹ Watts at the source, but the source is 410 Mpc away, or 1.26x10²⁵ meters away. (so not as faint as I thought...)

7

The Environment / Re: Could we clean out the air coming from ship funnels?

« on: 03/10/2019 15:37:45 »

I have split Hayseed's question off into a new topic, which can be found here: https://www.thenakedscientists.com/forum/index.php?topic=77831.0

8

The Environment / Re: Can we make shipping more efficient by generating a bubble between the boat and water?

« on: 03/10/2019 15:35:03 »

What if we could permanently place an air blanket on the hull?  The smooth surface of a bubble should have little drag.  Maybe a continuous disposable bubble.

Would graphene drag?  Perhaps a graphene balloon for a blanket.

Interesting approach to reducing drag... (I have split this off into a new thread because it was only tangentially related to the OP of the first thread it appeared in)

I wonder how the energy would compare between a hovercraft, vs just superheating the surface of the ship and using the Leidenfrost effect (https://en.wikipedia.org/wiki/Leidenfrost_effect). Presumably much more energy used to boil water than blow air, but not having any moving parts could make it easier to maintain (plus no barnacles!)

Best option is probably to use a superhydrophobic coating, but that could be very expensive (capex, not opex) and I don't know how well it would last...

9

The Environment / Re: Could we clean out the air coming from ship funnels?

« on: 03/10/2019 13:31:55 »

Waste can be remediated, alancalverd... but you're right that it probably won't be. Possibly better to use fuel cells and electric motors.

10

The Environment / Re: Will we end up with an atmosphere without any carbon dioxide eventually ?

« on: 03/10/2019 01:46:14 »

Forest fires are negligable in imact and are generally constant, so a small increace will only slightly increace levels. A study in the amazon said that the ammount of carbon stored in the wood in the amazon forest  is worth 100 years of UsA emmisions,

These statements seem contradictory to me. 100 years of USA emissions (at current rates) is quite significant, so even burning 0.5% would be a significant event. And while I would agree that there isn't typically that much variability in forest fires from year to year, there are also instances of major fires that can both release a significant amount of CO₂ as a direct product of combustion, and reduce the rate at which CO₂ can be absorbed in the near term.

when you realise the ammount of forest cleared across the earth by man in the last 3000 years there is alot more carbon released by that than fossil fuel, a few square miles of forest will not massively impact the current standing. The forests cleared show that the balance is not in equilibrium.

A few points:
(1) yes there is not currently an equilibrium--*we* are significantly disrupting that equilibrium, and pushing the system to a new equilibrium with significantly higher CO₂ concentrations than have been in the atmosphere at any point in the last million years or so.
(2) Comparing the deforestation we have caused over the last few millennia with the burning of fossil fuels over the last 200 years is not really a reasonable comparison.
(3) When I mentioned forest fires, I was not talking about a few square miles. I'm talking about epic rashes of forest fires like those that are likely to have occurred after major meteorite strikes or geologic activity. In just thee last few decades there have been examples of individual fires burning thousands of square kilometers of forest, and those are likely to be very small compared to what has happened (and will happen) on a scale of millions of years.

Also whilst a big enough increace in temperature will vent gas from the water, i believe the ammount of temperature increace is not enough to offset the increace ?

This was one of the examples of a positive feedback loop, so "offest" doesn't apply. (the hotter it gets, the more carbon dioxide comes out of the water, making it hotter, which drives more out of the water...)

11

The Environment / Re: Will we end up with an atmosphere without any carbon dioxide eventually ?

« on: 02/10/2019 20:32:56 »

In the next two or three billion years or so, it is unlikely.

Natural processes will establish some sort of steady state equilibrium that has a non-zero amount of CO₂ in the atmosphere. The equilibrium will shift around somewhat on both an annual cycle due to seasonal changes in deciduous forests, and a several thousand year cycle due to changes in temperature driven by external factors (like our orbit etc.), and there will be times when CO₂ levels spike due to volcanism or forest fires, or fall more quickly due to good growing years... but it will stay largely constant on a century-by-century basis.

While it is true that carbonate minerals are produced at the expense of atmospheric CO₂, these are calcined in the bowels of the earth as tectonic movements cause the deposits to be subducted. This CO₂ is released through volcanic eruptions as well as slower off-gassing processes.

Essentially, there are naturally occurring processes that can add to and subtract from the atmospheric CO₂ levels. Many of these are negative feedback loops (on long timescales, ie 10³ to 10⁷ years) so that the more CO₂ there is in the atmosphere, the faster it gets absorbed, and the more carbonate rock has been formed, the more quickly it gets consumed. Some of the components, however, are positive feedback loops (especially on short timescales, ie 1 to 10⁴ years), like more CO₂ in the atmosphere can increase the global temperatures, leading to less dissolved CO₂, and more forest fires, both of which lead to more atmospheric CO₂ (or the reverse). This leads to relatively rapid changes between a few distinct equilibrium points, which, once established, are fairly stable until a large forcing factor comes along, causing another rapid change to a new equilibrium point.

Once the sun turns into a red giant, our atmosphere will be stripped off, and then there isn't much point considering how much of the remainder is CO₂...

check out the "carbon cycle" for more info

12

Chemistry / Re: How can we calculate the rate of molecules touching a surface?

« on: 02/10/2019 14:24:04 »

For a first approximation you will also need to specify the temperature, and whether you mean water molecules and amino acid molecules, or just the amino acid molecules.

Unfortunately this first approximation is probably very poor because a 1M solution of amino acid in water is likely to be quite viscous, which will change the rates at which molecules can move around--and the identity of the amino acid will be important (for instance, glycine and arginine are VERY different!) Also the pH will play a role.

Also, you may wish to consider what the surface is... if the amino acids stick to it very strongly, there may be no reasonable definition of "rate" because the surface will just get covered in molecules that never leave.

As always... the more info you provide about what you are ACTUALLY interested in knowing, the better the answers will be.

13

Chemistry / Re: Why are most molecules in singlet state if the triplet state is lower energy?

« on: 01/10/2019 16:46:56 »

Molecules adopt the lowest energy state they can, subject to laws of thermodynamics (zero point energy and boltzmann distribution) and QM (Pauli exclusion principle). (sometimes it can take a while for a metastable state to decay into the most stable state--especially when a change in spin state is involved)

The energy of an electronic state involves contributions from electron-nucleus interactions (energy shell, n), electron angular momenta (L and m_L) and electron-electron interactions (electrostatic repulsion and exchange energy).

For molecules with an odd number of electrons, there will always be at least one unpaired electron (doublet).

For molecules with an even number of electrons the choice beetween singlet and triplet (or higher) will be determined by the interplay of the aforementioned contributions. Typically differences in orbital energy due to n, L, and m_L are sufficiently large to favor the singlet state. However, if there are multiple orbitals with the same energy (degenerate) or very close, then the energy due to exchange can lead to triplet (or higher) states being favored. (essentially, if there are multiple electrons in degenerate orbitals, it is slightly favorable for their spins to align, leading to a high spin state)

Subtle effects in molecular geometry or composition (breaking or forming degeneracies) can thus lead to more stable high spin states, or more stable low spin states.

O₂ is an example of a simple molecule that is more stable in the triplet state (having two electrons in two . degenerate π* orbitals--singlet oxygen can be produced by either chemical or photochemical methods, and is incredibly reactive).

Ni(II) atoms have 8 d electrons, which favor a singlet state when the ligands around the Ni ion are in a square planar arrangement, but favor a triplet state when the ligands adopt a tetrahedral or octahedral arrangement. Elements near the middle of their respective rows in the periodic table an form very high spin states because they have half-filled orbitals (like Fe(III) which can adopt a sextet state with five parallel unpaired electrons, or Gd(III) which can have an octet state with seven parallel unpaired electrons)

14

Physiology & Medicine / Re: Can I use apple cider vinegar to get rid of warts?

« on: 26/09/2019 18:17:49 »

I typically remove my genital warts with a belt sander. It bleeds a lot, and it hurts, but those warts disappear real quick!

My doctor thinks this is a bad idea, but what does she know?

(for those who can't tell... this is sarcasm. to paraphrase alancalvard, "see a doctor for medical advice")

15

Physiology & Medicine / Re: does blood sugar crash immediately after eating?

« on: 25/09/2019 19:21:13 »

It's normal to feel sleepy after a big meal - you don't need to eat more, but your gut takes energy to digest the meal.
See: https://en.wikipedia.org/wiki/Postprandial_somnolence

If it is large variation in blood sugar, that should be assessed by a doctor.
See: https://www.mayoclinic.org/diseases-conditions/diabetes/expert-answers/reactive-hypoglycemia/faq-20057778

I suggest eating food with a lower Glycemic Index - this releases the energy more slowly, and will affect blood sugar less.

Thanks evan_au!

Luckily, it appears that my symptoms are more in line with the first!

I think the solution, is to eat more frequent and smaller meals... hopefully my work schedule will allow it soon.

16

Physiology & Medicine / does blood sugar crash immediately after eating?

« on: 24/09/2019 19:13:20 »

I have recently gotten into a schedule that only allows me to eat two large meals a day (depending who you ask this is healthy or unhealthy... but that's not my question).

I often find myself getting hungry right before the big meal (no surprise there), but it is immediately after the meal, that I become completely incapable of performing the most basic thought processes--I am unable to focus, become irritable, and feel terrible. This lasts maybe 20 minutes, then I am right as rain.

At first I thought that this was just a lag time between when I got the food into my stomach, and when it finally reaches the blood, but that can't be the whole story... If I delay the meal by an hour I am still a little hungrier and grumpier ("hangrier") than I was an hour earlier, but not in such an extreme way. Then, like clockwork, as soon as I eat...wham!

What's going on?

17

That CAN'T be true! / Re: My new theory has been recognized by Google!

« on: 24/09/2019 18:54:16 »

...you do realize that anything posted online in a searchable format is "recognized by google", right?

18

General Science / Re: Proving or disproving theories: how does science work?

« on: 23/09/2019 16:57:04 »

Well, this is going off topic, but...

Money makes it easier for people to trade.

If person A has too many apples, and not enough bread, and person B has too much water, and not enough gasoline, and person C has too much gasoline and not enough apples, and person D has too much bread and not enough water... then without money they would all have to come together and do a big bartering operation involving all of them (very complicated and messy). But with money, each can sell what they have too much of at one point in spacetime, and buy what they need at another. Much more efficient!

19

General Science / Re: Proving or disproving theories: how does science work?

« on: 22/09/2019 21:29:41 »

Yes, unfortunately, increases in "total wealth" do not necessarily mean that more people are lifted out of poverty. The distribution of that wealth is also quite important. Wealth disparity is increasing very quickly (not too different from how things were in the 1920s).

Also, "wealth" as currently defined does not account for the value of environmental capital or the services rendered by natural phenomenon (how much is a rainstorm worth when it comes at the right time and place? how much risk does it pose if it comes at the wrong time and place? what is the value of the algae producing the oxygen we breath? or the geological features that cleanse the water we drink?)

20

General Science / Re: Proving or disproving theories: how does science work?

« on: 22/09/2019 20:40:14 »

One could turn this round and ask if it is the case that for science, seeing is believing.  Thus, if it looks as if there is such a thing as conservation of momentum, then that phenomenon must exist (or be true).  Similarly, we see apples falling to the ground.  On that basis science then posits the existence of a force, gravity, which makes the apples fall.  So the observation makes it look as if there is such a force as gravity.

This then leads me to wonder what  science is, exactly.  Clearly observation is very important in science, and so I ask myself if that is the aim of science?  That is, to describe the world?  Is the aim of science to describe the world rather than get at deeper, underlying truths about the world?

If science were merely trying to describe the world, we would have stopped at "apples fall."

Science not only seeks out the underlying fundamental truths about the world, but also seeks to harness it for the betterment of our technological prowess.

observation-->understanding-->technology
gravity applies to all things (and many other observations) --> Newtonian mechanics --> ballistics