To LogicGates (as addition to all what CharonY already stated):
DNA is not the origin of life. It simple words it is something like a passive, stable and precise data store which evolved later.
Most scientists think that RNA is in the beginning, even though there are other theories also (but no ones assuming DNA as the beginning).
The main reason for this is that RNA can act as a template to copy itself and is capable of catalyzing chemical reactions, while DNA can not catalyze and protein can not act as a template.
To understand better have a look at this good web page (I am not promoting any of my work here, I have nothing to do with this page ): http://exploringorigins.org/
Yes, calculation of abiogenesis is impossible, because we do not know how the first living structure actually looked like. In this repect "living" is meant to be something which is able to reproduce itself and can undergo evolution to gain additional properties.
Taking the minimum set of current living organisms to think of a life form which can reproduce itself leads to a still incredibly complex structure: A long RNA to encode all of the RNA and proteins needed, a copy enzyme (including proofreading), a translation enzyme set, all the enzymes needed to produce the ribose in RNA, the 4 bases in RNA, the 20 amino acids in protein, the membrane molecules, some transporter proteins in the membrane, the enzymes for the energy metabolism to create the polymers (RNA and protein) out of the precursor molecules, some enzymes to overcome the detailed issues of linear or circular RNA replication, and much more. Just a primitive piece of RNA with 1000 bases (which is actually nothing) gives you 41000 combinations and a probality of 1 / 41000 for a random abiogenesis (Of course only, if you assume that there are no other sugars present and no other bases, which is a completely wrong assumption. So actually it is even much less probable.). But the RNA mentioned above is much longer and this is still not enough, since it all needs to come together with the other pieces mentioned above and nicely put into one cell membrane. So this means, from what we can deduct out the biochemistry of living cells, this can never occur whatever timescale you take (including the complete earth as laboratory).
This means we have to think about what this first living structure actually looked like. And of course the more you know about the biochemical details, the more you tend to think that abiogenesis is a highly improbable event, because there is no simple solution of how a primitive self replicating and evolving molecule (or molecule system) could look like (but maybe somebody will find it one day). This is why you see a trend in the discussions, that biochemists and microbiologists tend to assume that abiogenisis is highly improbable and physicists tend to assume that it is simple (since they typically do not know the details).
To LogicGates (as addition to all what CharonY already stated): DNA is not the origin of life. It simple words it is something like a passive, stable and precise data store which evolved later. Most scientists think that RNA is in the beginning, even though there are other theories also (but no ones assuming DNA as the beginning). The main reason for this is that RNA can act as a template to copy itself and is capable of catalyzing chemical reactions, while DNA can not catalyze and protein can not act as a template. To understand better have a look at this good web page (I am not promoting any of my work here, I have nothing to do with this page ): http://exploringorigins.org/ Yes, calculation of abiogenesis is impossible, because we do not know how the first living structure actually looked like. In this repect "living" is meant to be something which is able to reproduce itself and can undergo evolution to gain additional properties. Taking the minimum set of current living organisms to think of a life form which can reproduce itself leads to a still incredibly complex structure: A long RNA to encode all of the RNA and proteins needed, a copy enzyme (including proofreading), a translation enzyme set, all the enzymes needed to produce the ribose in RNA, the 4 bases in RNA, the 20 amino acids in protein, the membrane molecules, some transporter proteins in the membrane, the enzymes for the energy metabolism to create the polymers (RNA and protein) out of the precursor molecules, some enzymes to overcome the detailed issues of linear or circular RNA replication, and much more. Just a primitive piece of RNA with 1000 bases (which is actually nothing) gives you 41000 combinations and a probality of 1 / 41000 for a random abiogenesis (Of course only, if you assume that there are no other sugars present and no other bases, which is a completely wrong assumption. So actually it is even much less probable.). But the RNA mentioned above is much longer and this is still not enough, since it all needs to come together with the other pieces mentioned above and nicely put into one cell membrane. So this means, from what we can deduct out the biochemistry of living cells, this can never occur whatever timescale you take (including the complete earth as laboratory). This means we have to think about what this first living structure actually looked like. And of course the more you know about the biochemical details, the more you tend to think that abiogenesis is a highly improbable event, because there is no simple solution of how a primitive self replicating and evolving molecule (or molecule system) could look like (but maybe somebody will find it one day). This is why you see a trend in the discussions, that biochemists and microbiologists tend to assume that abiogenisis is highly improbable and physicists tend to assume that it is simple (since they typically do not know the details).