"As far as the infinite expanses of the universe are concerned, a blanket statement of "______ exists" has a 100 per cent chance of being correct."

The universe (at least our universe) isn't infinite. We know the big bang happened a finite number of years ago, and we know space has expanded at a finite rate, so the universe's size has to be finite too.

"NASA researchers claim we might find yellow or even red plants growing in other galaxies."

Do you mean other galaxies, or other solar systems?

Unfortunately for blue plants, your inital premise:

'As far as the infinite expanses of the universe are concerned, a blanket statement of "______ exists" has a 100 per cent chance of being correct.'

suffers from two flaws.

First of all, most scientists do not believe the universe to be infinite. The latest estimate I heard was 156 billion light years (http://www.space.com/scienceastronomy/mystery_monday_040524.html) Gigantically humongous, to be sure, but infinitely smaller than infinity.

Second, infinite size does not imply infinite possibility. The majority of space is remarkably consistent: vacuum. Adding more space does not necessarily add more variety.

It's a pity, too, because your otherwise excellent argument is remarkably similar to that put forth by Douglas Adams in the Hitchikers Guide to the Galaxy to prove that the total population of the universe is 0, and that any person you may meet from time to time is the product of a deranged imagination. That is a very tempting philosophy...

that even here on Earth, there are blue plants. They are mostly found in the world's oceans. Also different chemical combinations could result in plants using uv or infra light for photosyntesis. The writer just couldn't think as far as common sense goes.

Sorry, but your comment, "As far as the infinite expanses of the universe are concerned, a blanket statement of "______ exists" has a 100 per cent chance of being correct." is incorrect.

For instance, suppose the statement is, "As far as the infinite expanses of the universe are concerned, a blanket statement of "Blue Plants exist" has a 100 per cent chance of being correct."

This is not guaranteed. Every single plant in the universe may be green. It's logically possible, therefore the "Blue plants exist" statement does not have a 100 percent chance of existing.

This logical fallacy is very widely distributed, but it's still false.

The following are based on things I have read here and there, but I cannot reference any specific sources, these being mostly (pop) sci magazines and the odd science/ physics handbook.

Firstly, there cannot be that much red light coming from sources other than the Sun, because then we would be seen everything red, even in the deepest of nights (a red viagra effect?).

Secondly, green accounts for about 50% of sunlight. A better choice (to chlorophyll) would be a substance absorbing green, utilizing at least 50% of sunlight. Evidence suggests that chlorophyll was an accident: it was the first thing that "nature came up with" and thus it became the preferred solution.

Thirdly, some plants (I think they are sea plants mostly), have evolved with such a substance (i.e. a green-absorbing one) and subsequently their colour is purplish. Perhaps being underwater, receiving less sunlight and with red being filtered out pushed their evolution to develop a more efficient photosynthesizer.

(Actually, the green of chlorophyll should be a good argument against the "Intelligent Design" non-theory: if for quite a few million years plans have been using a much less than optimum photosynthesizer, there cannot be much intelligence in their alleged design. Perhaps it should be called "Idiotic Design"-- it even preserves the initials...;-)

"In our solar system, more red light reaches Earth than other colors."

I know that a lot has changed in astronomy since I got my degree in the subject 23 years ago, but I distinctly remember that the spectrum of sunlight peaks in the yellow/green colour range.

Which is why the Sun looks yellow, and not red. Except at sunset, but that's Rayleigh scattering.

Surely black is the most likely colour to evolve, assuming there's a chemical similar to chlorophyll that can be used to absorb right across the visible spectrum.

Maximum energy absorption means minimum reflection, so the smart plants are dressed in black this season.

Um, we already have red and yellow plants on Earth... Looking out of my window I see some gold-coloured shrubs, and I'm pretty sure there's a copper beech around here somewhere.

If I remember my O-level biology rightly, there's four types of chlorophyll, and only two of them are green - the other two are red and yellow. I also seem to recall that the reason green chlorophyll dominates here is that red light carries more energy than green.

I'm not plant biologist, but wouldn't absorbing the entire visible spectrum possibly cause the plant to overheat? I didn't buy a black car with black interior for this reason.

Plants are basically the result of an ancient symbiotic relationship between heterotrophic eukaryotes and the photosynthetic autotrophs that were their prey. Its a little bit of a stretch to assume that extraterrestrial bodies would even have organisms that are like plants in form as well as function.

In our lakes and oceans we see plenty of single-celled organisms not too dissimilar from the ancient precursors to green chloroplasts, that come in every color you can imagine. Was it just the throw of the dice that the first plants were green, rather than using a more effective pigment with a different color? Some plants, such as the Azolla water fern, even form a secondary level of symbiosis with organisms that have different pigments than the plant itself, in order to capture an even greater slice of the spectrum.

Additionally, in many environments light energy is not the most important limiting factor for plant growth. Rather, nutrient supply, water availability, and growth space are frequently more restricted than light, suggesting that a more efficient pigment may not give a selective advantage after all. In fact, most plants have red and brown pigments to protect them from the bleaching effects of excess sunlight, such as copper beeches.

Light energy is so available in the universe that it seems almost inevitable that any planet with life on its surface (as opposed to chemotrophs in sea vents and the like) will have life forms that can harness that energy. But as we see on Earth, they most likely will exhibit a wide range of forms and colors.

Can we give the bloke a break? Seems to me all the comments regarding "______ exists" has a 100 per cent chance of being correct." miss the real point, which is a rather humourous (in my humble opinion) broad philosophical statement, and not an exact mathematical construct (e.g. in answer to the daft, but often heard question, "Does life exist anywhere else except Earth?") And, while we're on the subject of mathematical constructs, there is `infinity' and there is `infinity'; for instance, countably infinite is a legitimate mathematical idea, which rather closely approximates the Universe. You don't agree, eh? Please tell me when you finish counting all the particles in it then. There is also the possibility of infinite surfaces in finite spaces. We tend to think Cartesian, but imagine walking on the surface of a sphere (positive curvature) and keep going until you reach the `end'.

"The majority of space is remarkably consistent: vacuum. Adding more space does not necessarily add more variety."

Hate to pick the nit, but most modern astrophysicists peg the majority of our universe to be dark energy, followed by exotic dark matter. Since we don't know a whole lot about dark energy or exotic dark matter, we can not reject the idea that life forms might exist in space dominated by DE/EDM that are unique to the DE/EDM environment.

Based on our current understanding, adding space would mean adding dark energy and exotic dark matter to our universe at a 96:4 ratio to mundane dark matter and visible matter. Therefore, it is certainly not unreasonable to project that adding space to our universe might add significantly to the variety of life forms in our universe, although they would be life forms that we can't currently perceive owing, of course, to their being based on DE/EDM.

Actually infinity doesn't necessarily mean everything. For example, there are an infinite number of odd numbers, yet you won't find a single even number among them.

If we're being strictly scientific here (and, as this is a scientific article, I think we are) black isn't a colour. Neither, for that matter, is white. The former is the absorption (or absence) of colour and the latter is produced by the reflection of all visible colour waves.

Grey - well that's a bit of a grey area...

Sarah

(who only did Physics as far as O Level)