1. What is life?
Alfred Driessen
University of Twente
A.Driessen@utwente.nl
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 1 date: 5 January 2008

2. Content
What is life?
1. Introduction
2. What can we learn from philosophy?
3. More is different (P.W. Anderson)
4. Philosophical reflections
5. Conclusions
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 2 date: 4 January 2008

3. Game of Life (Conway 1970)
Game of life: Cellular Automaton
Rules
1. Any live cell with fewer than two live
neighbours dies, as if by loneliness.
2. Any live cell with more than three live
neighbours dies, as if by overcrowding.
3. Any live cell with two or three live
neighbours lives, unchanged, to the next
generation.
4. Any dead cell with exactly three live
neighbours comes to life.
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 3 date: 4 January 2008

4. Powers of ten (movie 1977)
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 4 date: 4 January 2008

5. Unity of living objects
comparison stone and living object (cow)
division of stone: result two (smaller) stones
division of cow: two parts of a cow's cadaver
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 5 date: 4 January 2008

6. Unity of living objects
comparison stone and living object (cow)
division of stone: result two (smaller) stones
division of cow: two parts of a cow's cadaver
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 6 date: 4 January 2008

7. View of Science on Life
P.W. Anderson*):
hierarchy of sciences according to:
elementary entities of science X obey the laws of science Y
Does this imply science X is applied science Y?
*) Science, 177, pp 393-396 (1972)
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 7 date: 4 January 2008

8. The vision of philosophers
Raphael, the school of Athens (Vatican museum)
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 8 date: 4 January 2008

9. Life according to Aristotle (384-322 BC)
By life we mean self-nutrition and growth with
its correlative decay.
De anima, book II,
Three levels: plants, animals, human beings
How to explain unity of living object?
Aristotle: hylomorphism
Life is supported by a principle of life, the form
(Greek morphe) which informs a certain material
(hylo) such that it is a living organism.
Form of living object: psyche (soul)
That what is real is the whole, the parts exist only virtually.
What is the difference between real and virtual?
Has to be determined by experience
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 9 date: 5 January 2008

10. A modern analogue to material and form
hardware - software
software is always implemented in some hardware,
for example: program file: on memory-stick
on CD
on hard-disk
as code written on paper
hardware, which is switched-on, has always certain information, i.e.
software
for example: tv monitor movie
tele-text
'snow' if only noise at input
In Aristotelian language: information, the form, has to be
implemented in some kind of hardware, the material, otherwise it is
not real, it is virtual, virtual reality
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 10 date: 5 January 2008

11. P.W. Anderson: More is different*)
Theoretical Physicist, born: 1923, Nobel prize 1977
Distinction between reductionism and
constructionism
The reductionist hypothesis does not by any
means imply a "constructionist" one: The ability to
reduce everything to simple fundamental laws
does not imply the ability to start from those laws
and reconstruct the universe.
*) Science, 177, pp 393-396 (1972)
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 11 date: 5 January 2008

12. Example I: a mechanical clock
The clock and its parts:
once assembled, all parts are
clearly visible and
distinguishable
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 12 date: 5 January 2008

13. Example II: quantum mechanical system
Quantum mechanics:
there are systems, that can be decomposed in its parts;
as long as the system remains, however, the parts can not be
distinguished, neither theoretically nor experimentally
examples:
-- superconductivity: Bose-Einstein condensation of Cooper pairs
-- superfluidity: Bose-Einstein condensation of helium atoms
-- entangled photons
technical term:
superposition, the particles are in a superposition state
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 13 date: 5 January 2008

14. Philosophical reflection
There are two ways of considering the relation between the
whole and its parts:
I) The whole adds nothing essential to the parts and the
fundamental laws governing these.
Extreme statement: Der Mensch ist was er ißt (Karl Marx)
(Man is what he is eating)
II) The whole has something (new laws, for example) beyond the
constitutive parts and the laws governing these.
In both cases, the whole can be reduced to its parts;
in II) the whole can not be constructed from the parts without
additional input.
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 14 date: 5 January 2008

15. Philosophical reflection about life
There is a strong unity exclusively observed in living objects.
Already in some relatively simple systems unity can not
constructed exclusively from its parts and the laws governing
these.
It should be expected that the most complex systems known to
us, i.e. living objects, can also not be constructed from its parts
and the laws governing these.
This line of argumentation is supported by:
Aristotle
Quantum mechanics
everyday experience
Alfred Driessen
What is life? Electrical Engineering and Applied Physics
801what-is-life.ppt slide 15 date: 5 January 2008