[extropy-chat] "Dead Time" of the Brain

[A B]

Hi Heartland (S.),
   
  Heartland (S.) wrote:
   
       "However, what David Masten has 
already pointed out is true which is that you can't conclude that mind process 
*stops* simply because you choose to view it inside Planck Intervals. If we were to 
choose to view reality just inside Planck Intervals then we would also be forced to 
conclude that no process can ever exist."
   
  Let me just say, that because my mail provider is convenience-challenged, I'm unable to view David Masten's last post, but I'll do my best with this anyway. As far as any consistent theories of physics go, the Planck Interval is the smallest use-able unit of Time. So any mind-process that exists must be executed *after* a span of time that constitutes *at least* a single Planck interval (and probably very many intervals). I agree *within* a single Planck interval, no process of any kind can occur. I could have been more clear when I wrote that.
   
  "Mind process is an *activity* of matter in space and time which is measured in 
longer time frames than Planck Intervals."
   
  I totally agree, but, those longer time frames consist of a large multiplier of individual Planck intervals.
   
  "But the main point is that at no time 
during execution of the process the activity of the process stops. Even during 
Planck Intervals matter that implements mind carries potential energy that will 
power a transition from one mind state to the next. In other words, mind process 
exists even during Planck Intervals."
   
  I think this is where things are going to get blurry. I agree, that even while a neuron is not firing, biological activity is still occurring. The dendrites are collecting neurotransmitters, the cell is conducting basic life support metabolism, etc. But a neuron is unique among any other cell in the body - and that lies in its role to conduct transmissions. As I understand it, it utilizes two different forms of transmission: a chemical one based on diffusion, and an electrical one. But the electrical discharge (the firing) is the limiting step in this transmission process.  Without these widespread electrical transmissions throughout the brain, cognition of any kind would be impossible - the brain would be effectively dead; unable to process information. It would be just a lump of tissue that was exchanging chemicals, like a liver housed in a skull. So, during those spans where no neuron is firing (~10 ^ 29 PI) no relevant process is occurring; any relevant processing
 (eg. chemical processing) at all would be limited to the individual neurons themselves, and I think we would both agree that a single cultured human neuron is not "alive" in any meaningful way - it's just executing biochemical processes demanded by the laws of physics. Neurotransmitters (and their processing) alone do not account for existence.
   
  "On the other hand, when mind stops, there 
exists a point in time when there is no force that can transfer one mind state to 
the next, meaning that the previous instance of that process has run its course. 
That point in time is the time of death."
   
  Yes, but the atoms and chemicals still exist, they still carry their potential energy, and if the vitrification is sufficiently fine, the structure of the neuron is still in place. If a patient were revived, the neurons would have no "choice" but to continue firing and processing.
   
  Here's how I would sum up my view. I agree, that when a mind-process stops, that individual has died. But a person isn't a constant, by definition after every moment of life, you are a different person - a copy, an imperfect one (for biological/physical reasons). I am constantly dieing and "re-living", the old versions of me are all dead. But you retain the *sense* of being alive because the structure of your brain retains a very close pattern (but not identical) to the person who has just died a moment before. But whether that death was simply due to the passage of Time (in Planck Intervals) or because your brain stopped transmitting signals should make no difference.
  In the end, our life is just an elaboration of basic physics (which has no goals), as you suggested.
   
  And a vitrified brain also retains a trajectory in space and time (and the atoms are still in motion). A vitrified brain would follow roughly the same trajectory as a living person who decided to lay down in a bed and never get up... I know that feeling some morinings ;-)
   
  Best Wishes,
   
  Jeffrey Herrlich  
  
 Heartland <velvet977 at hotmail.com> wrote:
  > Hi Heartland,
>
> I think you present a very good and intuitive argument. However, I think John K 
> Clark may have been on to something when he said that subjectively *he* would 
> still feel alive. I can show this by using some math.
>
> First, here are some basic parameters of a typical human brain:
>
> Total Number of Neurons: ~100 Billion
> Upper Limit on Firing Rate: ~1000 Hz (Thanks Martin and Stirling)
> Planck Time Interval: ~ 10^ -43 Seconds
>
> What a human would call the "present moment" in which they live represents a 
> span of Time. Time itself can be divided down to a very small interval, at least 
> as small as a single Planck Interval. Therefore, even if the firing of all the 
> neurons occurred at different, uniformly staggered times, there is a period 
> between the firings of any two (arbitrarily chosen) neurons which represents the 
> passage of a substantial number of Planck Intervals. In essence, what this means 
> is that a normal, functioning brain is actually continually alternating between a 
> functional and a completely non-functional state (like "on" and "off").


That's actually a very interesting perspective. However, what David Masten has 
already pointed out is true which is that you can't conclude that mind process 
*stops* simply because you choose to view it inside Planck Intervals. If we were to 
choose to view reality just inside Planck Intervals then we would also be forced to 
conclude that no process can ever exist.

Mind process is an *activity* of matter in space and time which is measured in 
longer time frames than Planck Intervals. But the main point is that at no time 
during execution of the process the activity of the process stops. Even during 
Planck Intervals matter that implements mind carries potential energy that will 
power a transition from one mind state to the next. In other words, mind process 
exists even during Planck Intervals. On the other hand, when mind stops, there 
exists a point in time when there is no force that can transfer one mind state to 
the next, meaning that the previous instance of that process has run its course. 
That point in time is the time of death.

S. 
_______________________________________________
extropy-chat mailing list
extropy-chat at lists.extropy.org
http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat


		
---------------------------------
New Yahoo! Messenger with Voice. Call regular phones from your PC and save big.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20060420/c7657b9f/attachment.html>