Life and physics
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Life and physics
Next peergrade assignment due February, 21!Provide meaningful answer to the physics of life?
Important concepts in physics of life/biophysics:
Physical constraints of life: TemperatureSensing and emission: mechanics, sound, light, temperature, particles (smell)
On the white slide I saw a
A. I saw a yellow cross
B. I saw a blue cross for 1-3 s
C. I saw a blue cross for 4-10 s
D. I saw a blue cross for 11-20s
E. I saw a blue cross for over 20s
On the white slide I saw a
A. I saw a red text
B. I saw a blue text for 1-3 s
C. I saw a blue text for 4-10 s
D. I saw a blue text for 11-20s
E. I saw a blue text for over 20s
Which after image of the background Green did you see?
Rank Responses
1 5
2 12
3 7
4 6
5 11
6 8
12
3
4
5
678
9
10
11
12
Complementary colors
Wikiwww.davidcalabrese.com
Human eye has 4.5 million cone cells and 90 million rod cells
Negative afterimages due to overstimulation of the rods and cones, which leads to
loss of sensitivity in the original pattern (color and intensity).
Positive afterimages: short lived due to persisting activity.
Can we detect individual photons?
perg.phys.ksu.edu
CCD light detection (by Willard Boyle – Nobel laureate and McGill graduate)
Wiki: Charge-coupled device
http://meroli.web.cern.ch
More sensitive, more expensive Used in most cameras
Sequential processing
Parallel processing
www.astro.cardiff.ac.uk
Single photon detection using long superconducting wire:
Wikiwww.davidcalabrese.com
Human eye has 4.5 million cone cells and 90 million rod cells
Frog can see 3 photons!
Human can see 15 photons (6% chance to see 1 photon)!
Eye can see better when primed
Wikiwww.davidcalabrese.com
Human eye has 4.5 million cone cells and 90 million rod cells
Different color sensitivity:
psns
Source: Rachel Casiday and Regina Frey
How many frames per second can a human eye see?
Rank Responses
1 24
2 1000
3 144
4 30
5 5
6 100
frame rate experiment
How many flowers do you see?
A. 0
B. 1
C. 2
D. 3
E. 4
F. 5
G. 6
H. 7
I. 8
frame rate experiment
How many flowers do you see?
A. 0
B. 1
C. 2
D. 3
E. 4
F. 5
G. 6
H. 7
I. 8
frame rate experiment
How many flowers do you see?
A. 0
B. 1
C. 2
D. 3
E. 4
F. 5
G. 6
H. 7
I. 8
You start to “see” the image when the image is longer than 40ms (rate=25Hz)
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