Viraj's Weblog

I've been reading a rather excellent book called The Living Cosmos. A major part of the book talks about how life possibly arose on Earth, and understanding its processes will help understand just how obvious such similar processes must be happening elsewhere.

One of the interesting theories is that since evolution requires variation through mutations, one way to increase the number of mutations is through radiation. This gives rise to all sorts of strange scenarios, where the sun, or even a nearby supernova or hypernova, could release some radiation that causes major shifts in the evolutionary fitness on Earth. The possibilities are endless.

But what really got me thinking is the concept of life itself. It turns out this is a very hard thing to define. Most scientists equate metabolism with life. Let's think about this for a minute, and look beyond the complex cells we have today, back to when the first complex molecules started to form. Why would they form?

The book has an excellent picture showing solar radiation being converted to heat, which is an increase in entropy towards a more probable state. So we go from a condensed improbable energy state to a dispersed probable energy state. Think of a gas spreading in a room. The steady state is when there is more entropy. Now, between this beginning and end stages are other stages that harness the energy. These are molecular bonds such as ATP. So energy is flowing from the sun, being captured by molecules with the creation of bonds, and finally being released by those molecules by the breakage of those bonds. It's a stairway effect, where energy trickles down. It's being harnessed, or stored, but eventually released in some way. Another similar process is radioactive decay, where you have elements themselves changing at an atomic level by electron states. An electron is raised to some level by the inflow of energy, and then moves to another level by the release of that energy. In complex molecules the release could be through mechanical energy, waste production, etc. It's all just a transfer and harnessing of energy.

Is this not the process of life itself? Let's now think about how such complex molecules like cells and their replication processes might have evolved. Let's say solar energy starts forming some complex molecules which we would consider lifeless. Again, these are forming through the harnessing, or rather the catching, of solar energy. Sort of like fusing material together if you will. The atoms are simply the road the solar energy travels, and the forming of molecules essentially the 'damage' the energy does on the road. Now these molecules want to revert back to their more probable state of more entropy. That is, they want to break those bonds and go back to the state they were in before the sun ran them over. So they do, but the sun comes back again to do damage. This creates a cycle, but the complex formations are completely reliant on the sun.

Now, let's say you are that molecule relaxing or breaking your bonds to go back to what you were. In that process you release some energy (again, the stairway). That energy could affect another molecule next to you. Remember all of this is happening on a much grander scale, so many varied molecules could be forming. Let's now suppose a neighbor molecule takes as input you in your probable state and spits you back out in your improbable high-energy state. Something like a stencil, where the input may be some collection of elements (along with solar energy) and the output being an advanced molecule similar to what the sun did on its own.

Now what happens? A cycle is created! While one molecule is breaking apart, another is there taking the very energy released by the breaking apart to create a brand new original molecule. But it can't go on forever because at some point there is energy wastage through heat, so the sun must come in again and add energy the process. This eerily sounds like night and day. How can it go on at night? With the storage of the energy that happened during the day of course.

Let's call the 2nd molecule the replicator, because it is actually recreating the 1st molecule. Here you can see we are not fabricating molecules out of nothingness, but rather always reusing what is in the environment. What you have is a chain reaction. Could such a reaction be the birth of life as we know it? Extrapolate this to much more complex molecules, and we can begin to envision how DNA and replicating proteins might have evolved. It's just all on a much more higher level. Take the original replicator pair of molecules and let's say they are considered a whole molecule by another much larger replicator. In other words, you could have recursion going on, where a replicator replicates a replicator .

It becomes apparent that to continue life you need to recycle what once was into something new. As long as you have the energy input you can do this. Once energy is used out of molecules they breakdown, but you need to create more for future work. This is the very essence of replication. That is, survival depends on replication with stored energy.

Many spark of life experiments involve putting ingredients in a bottle and submitting it to some high energy like electricity. But I wonder, is this the wrong approach? Instead, shouldn't we be trying to model molecules that would exhibit a chain reaction with even the minimal amounts of energy? This chain reaction would be further tweaked as it's progressing because there would be changes in radiation (the sun's energy wouldn't be uniform, and you'd have radiation sources other than the sun). I find it hard to believe that life started abruptly with some spark. If you consider life as progression down the energy stairwell perspective it all seems to make sense that complex energy-harnessing organisms would arise. We can consider a lifeform simply as a very large molecule with high-energy bonds, ready to break to perform any of the physical powers that such lifeforms will have. They can pick up objects, they can reproduce, they can eat, etc. Taken on a much grander level we as humans could just be another step in the stairwell towards entropy.

Why did I name this blog 'Life as waste elimination'? Well partly because I am sick, and partly because I look at waste elimination similar to the energy released through breakage of molecular bonds. The scheme can be applied at the cellular, molecular, and even atomic levels with electrons.