Dichotomy’s non-random science questions.

[ydoaPs]

Q25. Does the earth weigh exactly the same as it did about a billion years ago?

No. As you said below, there are meteors striking and spacecraft leaving.

 

Do plant and animal growth/birth rates affect the weight of the earth?

No, they just re-arrange the mass that is already there, so there is no difference in the "weight" of the Earth(if that even means anything).

[Mr Skeptic]

Conservation of matter is a fundamental of chemistry (disregarding specific cases like matter-antimatter annihilation, which requires antimatter). Basically, the law of conservation of energy plus the mass-energy equivalence mean that you can't create matter from nothing. Unless you're God, maybe. Some energy is stored in as potential energy (which looks like mass) in chemical bonds (tiny amounts) or as evidenced by the differing masses of different nuclei (the basis for fusion and fission energy)

 

Overall, the mass of the earth has increased a lot due to space debris falling down.

 

Due to the radioactive decay of uranium and such, some of the mass of the earth is turning into energy, but this is incredibly small. Even smaller is that energy plants store as chemical bonds, but that overall is zero because the plants are eaten for their stored energy.

 

Basically, you got the right idea. There is no free lunch, it had to come from somewhere!

[dichotomy]

Overall, the mass of the earth has increased a lot due to space debris falling down.

 

 

Q26. Does the space debris need to be travelling at a given speed to collide with earth, ala meteors? Or can space 'dust' get to earth without needing to be forceful?

 

Basically, you got the right idea. There is no free lunch, it had to come from somewhere!

 

Yippy!

[Mr Skeptic]

Q26. Does the space debris need to be travelling at a given speed to collide with earth, ala meteors? Or can space 'dust' get to earth without needing to be forceful?

 

It will fall at about escape velocity plus its initial velocity. Conservation of energy here, it gains as much energy falling as it would take to throw it back where it came from. So it will fall quite fast.

[dichotomy]

Q27. Can animal life evolve from plant life?

 

Q28. How many times did life evolve independantly on earth?

[iNow]

Q27. Can animal life evolve from plant life?

Isn't that exactly what happened?

[dichotomy]

Isn't that exactly what happened?

 

I don't know, that's why I asked what the accepted theory was.

 

I was under the impression that there was a reasonable theory that life might have evolved from scratch 2 (or 3) times independently? From separate chemical combinations that worked: 1. Plants 2. animals (and possibly a 3rd time into what we know as fungus, or was it algae?).

[Mr Skeptic]

Q27. Can animal life evolve from plant life?

 

I'd assume it is possible. However, I think animals evolved from heterotrophs of some kind, as plants would have little reason to become mobile and predatorial.

 

Q28. How many times did life evolve independantly on earth?

 

If it was more than one, the other one(s) got eaten by the cell. I don't think anybody is going to be finding that kind of fossils... I guess the answer would depend somewhat on what you mean by life.

[dichotomy]

I'd assume it is possible. However, I think animals evolved from heterotrophs of some kind, as plants would have little reason to become mobile and predatorial.

 

 

 

If it was more than one, the other one(s) got eaten by the cell. I don't think anybody is going to be finding that kind of fossils... I guess the answer would depend somewhat on what you mean by life.

 

To clarify, was there two separate cells, one for the beginning of the animal kingdom and one for the beginning of the plant kingdom? Did the two distinct cells branch off from the same primary cell? Did the cells originate separately and never had a common cellular ancestor, but used the same available energy and matter?

[Mr Skeptic]

To clarify, was there two separate cells, one for the beginning of the animal kingdom and one for the beginning of the plant kingdom? Did the two distinct cells branch off from the same primary cell? Did the cells originate separately and never had a common cellular ancestor, but used the same available energy and matter?

 

No, all living things come from a single common ancestor. This is due to certain similarities shared by all cells, implying the ancestor had DNA, ribosomes, cell membrane, etc; a very complex cell. First came bacteria, then archaea, then bacteria and archaea merged somehow to form eukaryotes. Eukaryotes have genes from both archaea and bacteria, and also some organelles that appear to have originally been specialized bacteria that became the mitochrondria and chloroplasts. Eukaryotes are the more familiar group that include plants, animals, fungi, protists.

 

Note that bacteria are able to transfer genes between themselves even if they are not the same species.

[dichotomy]

No, all living things come from a single common ancestor. This is due to certain similarities shared by all cells, implying the ancestor had DNA, ribosomes, cell membrane, etc; a very complex cell. First came bacteria, then archaea, then bacteria and archaea merged somehow to form eukaryotes. Eukaryotes have genes from both archaea and bacteria, and also some organelles that appear to have originally been specialized bacteria that became the mitochrondria and chloroplasts. Eukaryotes are the more familiar group that include plants, animals, fungi, protists.

 

Note that bacteria are able to transfer genes between themselves even if they are not the same species.

 

Thanks for the answer Mr Skeptic. I was hoping that different types of complex life could emerge from unrelated primary cells, but there you go. Life initially requires the same primary matter/energy to emerge as the types of complex life we know and love.

 

It's interesting that Bacteria can transfer genes across their various species. It shows how we are related to plants , very early on, of course. And to think, those mean vegitarians are eating our ancient ancestors.

[Mr Skeptic]

Oh, I forgot about viruses. I'm not sure where they came from. They could potentially be a separate line from our cell ancestor, or an unfortunate messenger RNA accident. Most people don't consider them to be alive though.

 

Anyone know where viruses originated?

[dichotomy]

Ok, so there are maybe three kingdoms that came from the same celluar ancestor then, animal, plant and virus?

 

Q 29. If alien life where to exist on a remote planet, would it likely originate from the same primary building blocks as earth life does?

[dichotomy]

Ok, so there are maybe three kingdoms that came from the same celluar ancestor then, animal, plant and virus?

 

Q 29. If alien life where to exist on a remote planet, would it likely originate from the same primary building blocks as earth life does?

 

 

Bump! Anyone?

 

 

Also,

 

Q 30. Can microbes really survive space atmosphere?

Has this been absolutely proven by U.S, Russian and Chinese based scientists?

[Mr Skeptic]

Bump! Anyone?

 

There's a significant probability that alien life would be based on much the same stuff we are. After all, its the only thing we know for sure that works. I think consensus is that it would have to at the very least be carbon-based (though some think that silicon based is also possible).

 

From the nature of proteins, they are a (NH₂)(CHR)(COOH) unit where the R group is basically anything (in practice there are about 20 different ones used in life). This is a rather simple thing, and very powerful as the amino group (NH₂) from one amino acid can bind to the carboxyl (COOH) of another, forming a peptide bond. Also, amino acids can form naturally under certain circumstances, so it is quite possible that alien life would use proteins, even if many of the R groups are different than terrestial proteins. As for DNA/RNA, these are larger molecules and I don't know how easy they are; also they are not as vital as proteins.

 

But basically, that is all speculation as there is a very good chance that there are other ways to make life than we know.

 

Also,

 

Q 30. Can microbes really survive space atmosphere?

Has this been absolutely proven by U.S, Russian and Chinese based scientists?

 

They can survive, at least for a time. But they won't be very happy, what with no oxygen, food, water (actually they're likelier to get freeze-dried), radiation... I don't think they will be metabolically active aka "alive and kicking". Actually, being freeze-dried can preserve them, and most bacteria can survive when frozen or dehydrated. If they are to get anywhere, they would have to survive some insane radiation, and I don't know that they can do that for long if they are not metabolically active (required for self-repair).

[dichotomy]

Q30. Can light on a textile, by itself, fade colour and break down the textile?

That is, if UV, infra red and heat are removed from the light source.

[Mr Skeptic]

Q30. Can light on a textile, by itself, fade colour and break down the textile?

That is, if UV, infra red and heat are removed from the light source.

 

Yes, for some materials regular light can drive reactions. Particularly in the higher energy portions of the spectrum. However, UV would definitely be far more damaging to far more materials.

[swansont]

Q30. Can light on a textile, by itself, fade colour and break down the textile?

That is, if UV, infra red and heat are removed from the light source.

 

Removing heat from the light source is impossible*; I assume by this you mean you are limiting the light to the visible spectrum. And the answer is yes, light at the blue end of the spectrum can do this in some cases, as Mr Skeptic said.

 

*visible light has energy and is thus a form of radiant heat transfer

[DrP]

plants would have little reason to become mobile and predatorial.

 

 

Hmmm.. what about the Venus Fly Trap? Or Triffids even?

[dichotomy]

Removing heat from the light source is impossible*; I assume by this you mean you are limiting the light to the visible spectrum. And the answer is yes, light at the blue end of the spectrum can do this in some cases, as Mr Skeptic said.

 

I'm thinking just visible light. No UV a,b,c, no infra red, no x-ray, gamma rays, nothing but light that illuminates darkness.

 

*visible light has energy and is thus a form of radiant heat transfer

 

At any length? Or point in its length?

 

Ok, what I’m thinking is if the directed light, from say a standard 12v 50w dichroic lamp, is about 3m above a red cotton t-shirt. Wouldn’t the heat just rise away from the t-shirt and not damage it, even over 10 years?

 

I'm having a friendly argument with a museum person regarding 12v 50w dichroic lamp light possibly damaging textiles, the lamps use UV absorbing glass and are between 2 and 5 meters away from what they are lighting. It seems unlikely to me that fading or damage could occur over 3 or 4 months of exposure.

[swansont]

It depends on the chemical makeup of the dyes used for coloring. There are effects from heat, and also on specific bonds from photon absorption and possible ionization. But this definitely extends into the visible, though the effect is not linear — UV does a lot more damage.

 

 

In the context of protecting works of art at a museum

http://www.padfield.org/tim/cfys/lightmtr/luxerror.php

[dichotomy]

Q31. What is the smallest observable thing?

 

Whatever it is, it can be observable with a very powerful microscope.

 

Is there a link to a photograph of it?

 

I was thinking of how far you could crush a grain of sand and still be able to observe its contents.

[Mr Skeptic]

Um, thats a good one. I think all the fundamental particles are point particles, making them all the smallest things we can observe. However, they have a wavenlength, which will limit how "small" they can be. Or, you could say that the lightest one is the smallest, even though it will have a larger wavelength.

 

In theory, you can get photons of any wavelength if you put in enough energy, so there's no theoretical limit in that sense to how small you can see. However, the smaller the wavelength, the more the momentum and energy, so you could end up blasting away whatever you wanted to look at.

[swansont]

Depends on what you mean by observable. Naked eye, or with instrumentation? What kind of augmentation — optical (so it's enhanced naked eye) or other (e.g. electron microscope)

 

The diffraction limit of the eye (Rayleigh criterion) at the near-point of vision is a few tens of microns, but of course that's not easily seen. Smaller than ~100 microns would be tough. If you add in optics, you have the limits of the optics and the wavelength of light, so about a micron would be the limit.

 

Atomic-force microscopes have imaged individual atoms, so that's at the nanometer level.

http://www.iap.tuwien.ac.at/www/opt/images/afm_surface.png

http://www.science.org.au/sats2004/images/bilek16.jpg

[dichotomy]

Depends on what you mean by observable. Naked eye, or with instrumentation?

 

Both types would be interesting to see.

 

Atomic-force microscopes have imaged individual atoms, so that's at the nanometer level.

http://www.science.org.au/sats2004/images/bilek16.jpg

 

So, with the 1nm labelled image, I assume that each light coloured dot is an observable individual atom, about as clearly as can be reproduced photographically?

 

Thanks for the image links.