next peergrade assignment due february, 21! provide

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)