Science's 125 Big Questions

Shadow Wrought writes "To celebrate their 125th anniversary Science is running a series of articles on the 125 Questions of Science. The top 25 each link to an article exploring the subject of the question in depth. Included are such questions as: Are we alone in the Universe? What are the limits of conventional computing? How did cooperative behavior evolve?"

Comments

How did cooperative behavior evolve?"

[team99parody]

That seems to be an easy one.

A preditor/parasite found that it's easier to keep eating if it doesn't kill off it's host completely. Small steps from there could make it benign to it's host; and further small steps can make it cooperative.

Re:How did cooperative behavior evolve?"

[Anonymous Coward]

Have you ever heard of the prisoner's dilemma? Tragedy of the commons? Read about these things.

Re:How did cooperative behavior evolve?"

[Shimmer]

It might seem to be an easy one, but your answer doesn't explain most cooperation.

Cooperative behavior arises out of an evolutionary phenonemon known as kin selection. The basic idea is that if you are related to another organism, you know that you are likely to share some portion of your genes. Thus, it's in your interest to assist your relative in surving to reproduce so that your shared genes are passed down.

-- Brian Berns

Re:Why?

[tktk]

I think this was answered in Sci. American a few years ago. It turned out to be the relationship between the average table height and the rotational speed of toast. Or it might have been the average height of a person and rotational speed of toast.

Given this average height, toast doesn't have time rotate more than half a turn before hitting the ground. If tables and people were something like 10 feet tall, then people would be wondering why toast allways falls with the butter side up.

Well, the 10 feet figure is made up but that's the basic idea from the article.

Good questions

[exp(pi*sqrt(163))]

My favourite is why does time have an arrow? This is closely related to one of the listed questions "why is time different from the other dimensions?"

Or to put it another way: Why does the entropy of any closed system always increase? Why do we take the 'causal' solution to Maxwell's equations when determining the field generated by an accelerating charge? Why does the evolution of a quantum system appear to involve an irreversible step - wavefunction collapse? These may in fact be the same question in different guises. I think it's the number one question in physics. Every fundamental law of physics has time reversal symmetry (or at least CPT symmetry) and 'future' and 'past' look as similar as 'left' and 'right' at a fundamental level. So the arrow of time we see so blatantly around us is in serious need of explanation. It's almost as if physicists live in denial about the fact that their fundamental theories clearly just don't seem to match up with reality. But there are some good books on the subject such as Zeh's.

Re:Good questions

[jd]

The arrow of time is a curious one. For photons, time must actually be frozen, as relativistic time at the speed of light is zero - even so, photons clearly experience events, otherwise there would be no photoelectic effect and the world would suddenly seem a lot darker - mostly because eyes wouldn't work.

Now, this is only in relation to someone INSIDE the Universe. Someone from an external frame of reference (if such a concept exists) would see the entire of space/time as a single four-dimensional entity. There would be no "time", because time is a product of being on the inside of the system.

This seems to answer the question. Your position along the time axis of space/time is your position relative to event zero, along the time axis. The Universe only expands, so the time arrow can only face outwards.

Problem. Steven Hawking demonstrated that if the Universe were to contract, entropy would STILL increase on any kind of scale. In other words, there would still be some measure (which we can call time if we like) which can ONLY increase, never decrease.

This complicates the picture, because if time can only increase (even when the Universe is contracting), then time is NOT a simple linear measure. Ok, then what is it? Well, simple logic suggests an answer, but simple logic can be wrong. The suggested answer involves taking the absolute value, which must always be positive.

However, you can't just throw away the sign of a number and leave it at that, there has to be some reason why you would do this. Let us say that real time is, in fact, TWO dimemsional, and that the time we experience is along a vector in that space. Well, the length of a 2D vector can be calculated quite easily. Treat the end-point as a complex number and take the absolute value.

Now, treating time as a two dimensional entity raises its own problems. Why two? Why not three? Or four? In fact, this leads me back to another post I did a while back, relating space and time as vectors, when discussing relativity.

Let us treat space/time as a single four dimensional entity. A plain, ordinary four dimensional entity. Nothing special about any of the dimensions, nothing unique, nothing out of the ordinary - other than being four dimensional.

Now, if subjective time is plotted as the vector we are travelling along in this 4D space/time system, then subjective time is (again) the absolute value of that vector and must always be positive as a result, regardless of the behaviour of "physical" time.

Ok, does it make sense to regard subjective time as the vector we are travelling in? That one, I can't answer, but a very superficial glance would indicate that it would seem logical enough. The vector indicates a speed of some sort, so why not the speed of subjective time?

Why humans have so few genes

[G4from128k]

The article on why humans have so few genes does some nice hand-waving but fails to answer the core question. Sure, the genome can do some interesting combinatoric stuff to get more out of a given length of DNA, but that does not answer the question -- why should humans have fewer genes than something so simple as a mustard plant or rice?

I suspect the answer is related to human (mammalian) mobility and thermoregulation. If a rice plant gets stuck in a hot place, all it can do is use a different part of its genome to make proteins suited for hotter weather. In contrast, people can move out of the sun while their body basically maintains a constant temperature. Similarly if the plant faces too much cold, too much water, too little water, to much sun, too little sun, too much salt, etc. it can do nothing but sit there and hopefully pull something out of its genome that can cope.

The point is that plants must adapt to whatever their environment gives them much more so than humans. Human mobility and the ability to modify its environment means it is less reliant on gene-based adaptability.

Re:Why humans have so few genes

[rdwald]

I would guess that we have so few protein-encoding genes because we have a large amount of non-protein-based regulatory machinery. In particular, the study of RNA-based regulation in mammals has exploded in the past few years, and it looks like a huge amount of regulation takes place without proteins. I would bet that many of the things which are done crudely in plants with proteins are done in extremely complicated fashions with RNA-based regulation in mammals. That isn't to say that proteins aren't involved; rather, I expect that we can get much more use out of a single protein when that protein's behaivor is affected by RNA in the cell.

Re:Why humans have so few genes

[John Newman]

In particular, the study of RNA-based regulation in mammals has exploded in the past few years, and it looks like a huge amount of regulation takes place without proteins. I would bet that many of the things which are done crudely in plants with proteins are done in extremely complicated fashions with RNA-based regulation in mammals.

Plants have equally interesting RNA-based regulatory mechanisms. Some of the early RNAi-based gene silencing work was done in plants. And recently, there was a suggestion that plants might carry an RNA backup copy of their genome.

In fact, RNAi was first discovered in the lowly worm, and the pathways are fully formed in even-lowlier yeast. RNA-based regulation might go way back - a relic of the RNA world, when proteins were new (or nonexistant). We mammals might have a few claims to fame, but RNA-based regulation isn't one of them. :)

There is only one real question

[VividU]

What is the nature and origin of the Universe?

Now that is the real question. And I'm not talking Big Bang or Grand Unified Theory or whatever. I'm talking "Big Picture" here.

What existed before our universe? What is the original nature of existence...of what we call "reality"?

Re:There is only one real question

[rossifer]

What is the nature and origin of the Universe?

It is and has been. (seriously, that's all the answer there is).

What existed before our universe?

Unknowable. "Before" the universe began is "before" the concept of time has any meaning. Alternatively, if we could observe things that were "outside of the universe", we would have to expand the scope of the universe to include those observations, meaning that they were no longer "outside of the universe".

What is the original nature of existence...of what we call "reality"?

This is a vague question. One possible interpretation is that you're asking about the "super-universe" in a different way from the "before the universe" question. It has the same problems as the "before the universe" question (if we could know, we'd have to redefine the universe).

The other interpretation is that you're asking if the nature of reality has changed through the lifecycle of the observable universe, presumably though alterations of fundamental laws from some initial "ideal" state. This question, while clearly less "grand", is more relevant, because it offers a source of falsifiable assertions and possible experiments.

Being able to classify questions as "irrelevant" and "not answerable" for various reasons is a part of "knowing what you don't know" and the rather tricky subset, "knowing what you can't know". Wisdom (and a lot of saved time) lies in a deeper understanding of how to determine the value of questions.

I must admit that about 12 years ago, I got comfortable with saying "I don't know" along with the realization that people are capable of asking bad questions as if they were the most important questions around. My favorite is "Why are we here?" It's worthless because it begs about four other questions that have no objective answer.

The interesting form of the question is, "Why am I here?" and it can only be conclusively answered by exactly one person: the same person who asked the question. What's really tragic is how many people are afraid of answering it themselves and accept someone else's answer out of fear of "getting it wrong". *sigh*

Regards,
Ross

Re:There is only one real question

[khallow]

This is a semantic problem. There are really two definitions of "universe". In the first, it is merely the collection of everything we currently see and know, our best guess. This "universe" definition can be expanded as we grow in knowledge and make more sophisticated observations. The second definition of universe is universal. It is the encompassing of all reality whether we know of it or not.

So several points to make here. First, while I think a universal "universe" exists, it's possible that the axioms of this object cannot be determined by Turing machine processes (perhaps determining the extent of the universe is equivalent to the stopping time conjecture). That would make it virtually impossible for humans to every know the rules of the universe, unless we can get a machine that is computationally more powerful than a Turing machine - even the quantum computers are equivalent computationally to a classic Turing machine. Ie, they don't do any computations that a Turing machine can't do. Same with nondeterministic Turing machines. They don't do anything new, just do stuff faster.

Second even if theoretically possible, it may require a prohibitively expensive growth in the cost of observations to determine this object (eg, nobody may want to sacrifice several galaxy clusters to get the next step in energy).

So it may be that the two definitions of universe will in practice remain seperate forever.

Here's one for you...

[Short Circuit]

...What is conventional computing?

Is it binary operations implemented with semiconductors? Is it the use of a monolithic computation device to perform generic tasks?

Or is it something more nebulous, like the ability for an individual's performance to be improved through the use of a computer? The use of an extremely configurable tool to aid in specific tasks with real-world results?

Add Saturn to the queue

[yohohogreengiant]

Saturn is rotating slower: And Saturn is rotating seven minutes more slowly than when probes measured its spin in the 70s and 80s - an observation experts cannot yet explain.

Re:You know...

[jd]

You know what that means. 42 + 42 + 1 = 125! However, in base 13, 42 + 42 + 42 + 42 + 1A = 125.

Re:Why so much bio?

[tootlemonde]

all of the interesting physics problems can be concatanated into a small number of questions.

Given the mathematical basis of physics since Newton, physicists are able to show that disparate phenomenon have a common mathematical formulation. This reductionism results in fewer and fewer unrelated questions.

If biology had achieved the same level of quantification, there might be a smaller number of questions.

For instance, if there were an answer to "What is the origin of homochirality in nature?", then it might be apparent that the following questions were related:

• Can we predict how proteins will fold?
• What keeps intracellular traffic running smoothly?
• What enables cellular components to copy themselves independent of DNA?
• How is asymmetry determined in the embryo?

Biology, unlike much of physics, has immediate practical applications in, for instance, medicine. Therefore, much of the research in biology is aimed at solving a specific problem rather than solving a fundamental problem.

For instance, some questions are related to curing cancer, e.g., "Are stem cells at the heart of all cancers?", "Is cancer susceptible to immune control?" and "Can cancers be controlled rather than cured?" Because lives are at stake, most researchers are not willing to put off tackling these questions until a more fundamental understanding of life is achieved.

The result is that the research effort is dilluted rather than concentrated on a search for underlying principles.

These gaps in the understanding of biology leave it a fertile area for pseudoscience like creationism and New Age medicine. Non-material explanations have been driven out of physical phenomena in chemistry, physics and astronomy in large part because the mathematical models are so complete.

Darwin was, in a way, too good a writer. Anyone can read him with reasonable comprehension and bid to criticize him. Had Darwin been a mathematician, medical research might be a branch of mathematics and evolution would have the same level of certainty as the helio-centric solar system.

Re:You ask for much

[king-manic]

The big picture is about existance itself. Why does "existance" exist? It's a depressing question because I don't think it'll ever be answered, and I can't keep thinking about it.

Does there need to be a why? As history has shown us, hows are all there is, why are often superflous questiosn we ask because we're bored.

Some question I've never been answered

[Spy der Mann]

We all know that particles (i.e. electrons, protons) with opposite charges get attracted to each other.

My question is...

WHY? Yes, I know they're opposite charges, and the Coulomb's law and everything... but why? Any quantum physicist to enlighten me?

Re:Some question I've never been answered

[HuguesT]

Science never answers to the question "why". Science proposes models (theories) that allow scientists to make predictions accurate to some degree, that is all.

The Coulomb law is such a model, but it is as similar in accuracy with respect to the way electrons really behave as Newtonian mechanics is to the way gravity really works -- i.e. you can make very good predictions from the Coulomb law (Ohm's law, macroscopic electric fields, etc), but you can't predict lighwaves. The next level up would be the Maxwell equations, but still you don't get the "why".

You can derive the Maxwell equations from the relativistic equations of motion of a single electron, so they are pretty fundamental, but that doesn't answer your question. One of the things you can can derive from the Maxwell equations is that magnetic fields and electric fields behave in fundamentally different ways. In particular both fields are oriented (so you should expect positive and negative charged particles, and those particles behave in opposite ways in magnetic fields), but while you can have electrically charged particles, Maxell's equations tell you you can't have magnetic particles. Magnetic monopoles are impossible, they always come in pairs.

Why? we don't know. That's just how things are. However QM, since Dirac, predicts that Magnetic monopole should exist (they have never been observed).

At any rate, the Coulomb law and the Maxwell equations break down at the quantum level. You can look up more fundamental models, which for electrons today would be QED (quantum electro-dynamics), the theory for which Feynman, Swinger and Tomonaga got their Nobel in the 60s, or more generally the Standard Model. In these, electromagnetic interactions occur through the exchange of photons (virtual or real).

But still they would not answer to the question "why". At best you have a model of "how" things work.

We do know the standard model breaks down in some instances, so even if you understood it perfectly, still you wouldn't have a perfectly accurate model of "how" things really work, and you would get no closer of the "why" answer.

I'm not sure this helps...