So long as we have imprecise measurements and only a finite amount of matter and energy then time is not an issue because we eventually run out of unique (or distinguishable by any of our measurements) humans that can exist and we can just ask the nearly equivalent question: “what is the probability that I am in the last 95% of unique humans to ever exist?” At some point every possible human has been created and out of that huge finite number each one of us is an index. The question is whether the heat death stops the creation of humans in this universe before 20 times the current number of humans has been created (for the 95% argument).
However, the statement of the problem completely ignores prior probabilities. For instance it’s possible that we now have more than 5% of the total human population alive right now (that would be true if only 100 billion have ever lived). That would mean that the oldest people alive right now have a 0 probability of being in the last 95%. Additionally, we have a very good idea of whether we are in the last 99.9999999% of humans who have ever lived; the last 7 babies baby born on Earth have a slightly positive probability, everyone else has a 0 probability. What is the probability that 7 more babies will be born, replacing the current 7 who have the possibility of being the last? 1 for all practical purposes. 100 babies? Same. In fact it probably already happened while I was writing this comment. A billion? Probably still very, very close to 1. The calculation can be extended into the future based on our knowledge of our environment and society and the probability of existential risk. Unless we have a good reason for predicting the destruction of all humans we shouldn’t predict that we are in the last 95% of unique humans. Humans are built to reproduce, they have an environment that will probably last thousands if not hundreds of thousands of years, and they are learning to build their own environments anywhere they want. These facts are far more important than which particular brain is randomly selected to think of the doomsday argument.
EDIT: The part about the last 95% of humans is wrong if there are more than 5% still alive; it would have to be some of the first 5% still alive for the argument to be wrong for them today.
This is an assumption based on our current level of science and technology and failure of imagination. There are many possible ways around it: baby universes, false vacuum decay, even possibly conversion of dark energy (which appears to be inexhaustible) to normal matter, to name a few.
However, the statement of the problem completely ignores prior probabilities
I was unable to follow your logic there… Are you saying that the Doomsday argument is wrong or that it is irrelevant or what?
This is an assumption based on our current level of science and technology and failure of imagination. There are many possible ways around it: baby universes, false vacuum decay, even possibly conversion of dark energy (which appears to be inexhaustible) to normal matter, to name a few.
That may reveal a weakness in the doomsday argument itself. For instance, did any of the first hundred bllion billion humans even think of the doomsday argument? If the doomsday argument is flawed, will many future humans think of it more than briefly from historical interest? The nature of the human considering the doomsday argument significantly affects the sample space. Future humans in a free-energy universe would immediately see the falsehood of the doomsday argument and so from our perspective wouldn’t even be eligible for the sample space. It may be that the doomsday argument only has a chance of being seriously considered by a 20th/21st century human, which simply turns the question into “what is the probability that I am somewhere between the 100 billionth and 130 billionth human to ever live?” or whatever the appropriate bounds might be.
I was unable to follow your logic there… Are you saying that the Doomsday argument is wrong or that it is irrelevant or what?
The doomsday argument is correct if no other information besides the total number of humans who have lived before me and finite resources are assumed. With additional information our confidence should be increased beyond what the doomsday argument can provide, making the doomsday argument irrelevant in practice.
So long as we have imprecise measurements and only a finite amount of matter and energy then time is not an issue because we eventually run out of unique (or distinguishable by any of our measurements) humans that can exist and we can just ask the nearly equivalent question: “what is the probability that I am in the last 95% of unique humans to ever exist?” At some point every possible human has been created and out of that huge finite number each one of us is an index. The question is whether the heat death stops the creation of humans in this universe before 20 times the current number of humans has been created (for the 95% argument).
However, the statement of the problem completely ignores prior probabilities. For instance it’s possible that we now have more than 5% of the total human population alive right now (that would be true if only 100 billion have ever lived). That would mean that the oldest people alive right now have a 0 probability of being in the last 95%. Additionally, we have a very good idea of whether we are in the last 99.9999999% of humans who have ever lived; the last 7 babies baby born on Earth have a slightly positive probability, everyone else has a 0 probability. What is the probability that 7 more babies will be born, replacing the current 7 who have the possibility of being the last? 1 for all practical purposes. 100 babies? Same. In fact it probably already happened while I was writing this comment. A billion? Probably still very, very close to 1. The calculation can be extended into the future based on our knowledge of our environment and society and the probability of existential risk. Unless we have a good reason for predicting the destruction of all humans we shouldn’t predict that we are in the last 95% of unique humans. Humans are built to reproduce, they have an environment that will probably last thousands if not hundreds of thousands of years, and they are learning to build their own environments anywhere they want. These facts are far more important than which particular brain is randomly selected to think of the doomsday argument.
EDIT: The part about the last 95% of humans is wrong if there are more than 5% still alive; it would have to be some of the first 5% still alive for the argument to be wrong for them today.
This is an assumption based on our current level of science and technology and failure of imagination. There are many possible ways around it: baby universes, false vacuum decay, even possibly conversion of dark energy (which appears to be inexhaustible) to normal matter, to name a few.
I was unable to follow your logic there… Are you saying that the Doomsday argument is wrong or that it is irrelevant or what?
That may reveal a weakness in the doomsday argument itself. For instance, did any of the first hundred bllion billion humans even think of the doomsday argument? If the doomsday argument is flawed, will many future humans think of it more than briefly from historical interest? The nature of the human considering the doomsday argument significantly affects the sample space. Future humans in a free-energy universe would immediately see the falsehood of the doomsday argument and so from our perspective wouldn’t even be eligible for the sample space. It may be that the doomsday argument only has a chance of being seriously considered by a 20th/21st century human, which simply turns the question into “what is the probability that I am somewhere between the 100 billionth and 130 billionth human to ever live?” or whatever the appropriate bounds might be.
The doomsday argument is correct if no other information besides the total number of humans who have lived before me and finite resources are assumed. With additional information our confidence should be increased beyond what the doomsday argument can provide, making the doomsday argument irrelevant in practice.
Thanks, this makes sense.