It is a rule of physics that information can鈥檛 disappear. So what happens to the information in my brain when I die?
Lewis O鈥橲haughnessy Nottingham, UK
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Physics tells us that while the physical structures that encode information can never be destroyed, they can be altered. Importantly, they can be changed in such a way that it is practically impossible to recover the information, even though it remains a technical possibility.
If you ran a computer鈥檚 hard drive through an industrial shredder several times over, for example, it would theoretically be possible to stick every fragment back together in exactly the same way as before, although such a feat could never be achieved.
鈥淚f I write something on a piece of paper and burn it, the information, in physics terms, hasn鈥檛 been lost鈥�
Much the same thing occurs in the brain after death. The information we store there is encoded primarily by the connections of synapses, but after we die, these start to degrade. In theory, you could stick every atom back exactly where it originated, but this obviously isn鈥檛 possible in practice.
When we die, the brain structures that hold information are changed beyond recognition. The information is still there, but it is practically irretrievable.
Penny Jackson Barrow-in-Furness, Cumbria, UK
鈥淚nformation鈥� doesn鈥檛 have quite the same meaning in physics as the everyday use of the word. In physics, it means information about the properties of fundamental particles 鈥� their charge and whether they are a lepton or a quark, for instance, as well as more classical properties such as energy and momentum.
Particles can change, but certain symmetries must be observed. For example, an electron (charge -1, lepton number +1) can annihilate with a positron (charge +1, lepton number -1) to create a pair of photons, but not with a proton (charge +1, lepton number 0).
No ordinary process, including the decay of human bodies, violates this. The one possible exception is when matter disappears into black holes. Stephen Hawking famously made a bet that information is lost when black holes evaporate, but later conceded that it probably is preserved.
If I write something on a
piece of paper and then burn
it, the information (in everyday terminology) has been lost, but in physics terms, it hasn鈥檛. Chemical reactions happen to the paper and ink, but no fundamental particle properties change, with a possible exception if I were to toss the ashes into a black hole.
John Williams Norwich, Norfolk, UK
Can information disappear? It all depends on the definition used. I use the definition that information is what determines how two entities interact, be they two hydrogen atoms or a person and a bus timetable. Information in the properties of a hydrogen atom may not be destroyed unless you split up the hydrogen atom. Brain information is created by us and therefore, on death, can be destroyed.
Moira Jamieson Chudleigh, Devon, UK
Many people who have near-death experiences describe having a life review, backwards from the present. Could this be a download into a block universe in a higher dimension, updating it ready for the next universe cycle? No information lost, merely stored away for future use. Just a thought.
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