ET Might Write Not Radiate Christopher Rose 1 and Gregory Wright 2 1 WINLAB Rutgers University Piscataway, New Jersey 08854 USA 2 Antiope Associates 18 Clay Street Fair Haven, New Jersey 07704 USA March 24, 2004
� � ✁ � ✁ ✁ Write Not Radiate 1 10 Years of WINLAB Research (Infostations redux) Infostations: – Delay tolerant? transmit when near base! Channel Quality – How good can that RF channel be? really good! Interference Avoidance, Pricing & Spectrum Management – Interference hurts deal with it! WINLAB C. Rose DIMACS Storage 3/24/04
� � � � � Write Not Radiate 2 An Epiphany! RF Interference is bad Storage density is increasing Channel good when nearby Can tolerate delay IMPLICATION: – Forget RF! Write message down! Toss it to recipient! Completely ridiculous ......... right? WINLAB C. Rose DIMACS Storage 3/24/04
✁ � � ✁ � � � ✁ � � ✁ � � Write Not Radiate 3 A Little Empirical Rigor 10 18 bits/kg Optical Lithography with SiO 2 : 3 85 10 21 bits/kg E-beam Lithography with SiO 2 : 1 54 10 22 bits/kg STM with Xe on Ni: 1 74 10 24 bits/kg RNA : 3 6 And maybe a LOT more room at the bottom WINLAB C. Rose DIMACS Storage 3/24/04
Write Not Radiate 4 A Little Analytic Rigor R 2 π aperture D 0 r 0 D mass delivered radiated message Radiation T Mass Transport τ =D/c+T D/c 0 WINLAB C. Rose DIMACS Storage 3/24/04
� ☎ ✁ � ✁ � ☎ ✁ ☎ � ✂ ✄ � � ✁ ✄ � ✁ ✄ � � ✁ ✂ � Write Not Radiate 5 Communications Theory IS Rocket Science Max bigger than mean: max h v E h V v If V deterministic: max h v E h V ✁✝✆ v If h convex (Jensen): E h V h v ¯ WINLAB C. Rose DIMACS Storage 3/24/04
✁ � � � ✁ ☎ � � ✁ ✆ ✄ ✆ ✂ ✁✂ � ✁ ✁ � ✂ � � � ✁ � ✁✂ � ✄ � � � ✆ ✁ ✁ ✆ ✁✂ ✁ ✆ ☎ ✆ ✁ Write Not Radiate 6 Rocket Science Average velocity τ 1 D 0 v t dt v ¯ E v t τ τ Minimum imparted energy min max E h v t t v D subject to ¯ v τ . Jensen says E min max h v t min E h v t h v ¯ t v v with equality iff v t is constant WINLAB C. Rose DIMACS Storage 3/24/04
✆ ✁ � ✂ ✁ ✄ ✁ � � � � � ☎ ✁ � ✁ � ✆ � � � Write Not Radiate 7 Minimum Transport Energy GIVEN: h and ¯ v E h v ¯ 1 mc 2 1 : h v ✁✝✆ v 2 1 c 2 1 mc 2 E 1 2 ¯ v 1 c 1 2 mv 2 : h v ✁ ✆☎ 1 v 2 E 2 m ¯ WINLAB C. Rose DIMACS Storage 3/24/04
✁ � � � ✂ � ✁ ✁ ✁✂ � � � ✁ � ✁ ✁ ✆ ✁✂ � ✂ ✆ ✁ ✂ � � ✁ ✁ ✁ � ✂ � � ✆ Write Not Radiate 8 Potential Fields Setup q x potential energy: t h v t q x t E ✁ ✁� Energy minimization: τ 1 E min max t min t dt E 0 E τ t x x Calculus of variations: ∂ E ∂ E d 0 ∂ v ∂ x dt xh ¨ x ˙ q x 0 ✁✝✆ WINLAB C. Rose DIMACS Storage 3/24/04
✆ � ✁ � � ✁ � � � � ✁ � ✂ � ✂ ✁ � ✆ � Write Not Radiate 9 Potential Field Results Non-relativistic: m ¨ x q x q x is force at position x : “free fall” Freefall? E t constant constant minimization satisfied with equality, so ... E t . WINLAB C. Rose DIMACS Storage 3/24/04
✆ � ✁ � � ✁ � � � � ✁ � ✂ � ✂ ✁ � ✆ � Write Not Radiate 10 Potential Field Results Low speed: m ¨ x q x q x is force at position x : “free fall” Freefall? E t constant constant minimization satisfied with equality, so ... E t WINLAB C. Rose DIMACS Storage 3/24/04
� ☎ ✆ � ✁ � � ✆ ✂ � � ✁ ✆ � � Write Not Radiate 11 Artillery Problem Minimum energy: 1 E 2 mgD Let δ c τ D – δ 1 near light speed – δ 1 low speed Delay at minimum energy δ 2 c gD Pay a factor of 2 over free space WINLAB C. Rose DIMACS Storage 3/24/04
✁ � ✁ � � � ✁ � � � � � Write Not Radiate 12 Escape Problem Needs numerical calculation Boils down to: need initial velocity larger than escape. Some energy penalty (but not a lot) Escape examples (rough): – Earth: δ 10 4 2 7 – Solar: δ 10 3 7 1 – Milky Way: δ 10 2 6 WINLAB C. Rose DIMACS Storage 3/24/04
� � ✁ � � ✂ � ☎ ✆ ✁ � ☎ � � ✁ � ☎ ✂ Write Not Radiate 13 Inscribed Matter Energy Requirements ρ Message size B , mass information density ˜ General δ B ρ c 2 E w 1 δ 2 ˜ 1 δ 1: 1 B c 2 E w ρ δ ˜ 2 Off by only 10% at 0 4 c and 50% at 0 75 c Low speed ain’t so low! We’ll ignore relativity WINLAB C. Rose DIMACS Storage 3/24/04
✁ ✆ ✁ � � ✆ � ✂ ✆ � � � ✆ � Write Not Radiate 14 Radiation Energy Requirements Energy capture AG ν D 4 π D 2 ✁✝✆ Bits a la Shannon: PGA B TC TW log 2 1 4 π D 2 N 0 W E r PT , 4 π D 2 TW B E r BN 0 2 1 TW AG B Large TW : 4 π D 2 E r BN 0 AG ln2 WINLAB C. Rose DIMACS Storage 3/24/04
� � ✂ � ✂ ✁ Write Not Radiate 15 Radiation to Transport Energy Ratio Definition: E r Ω E w Large TW , δ 1 ρ N 0 4 π D 2 ˜ Ω δ 2 2ln2 c 2 AG WINLAB C. Rose DIMACS Storage 3/24/04
Write Not Radiate 16 6 - 10 Energy Capture Bound 20 10 Arecibo@10GHz 1 10m Optical (500nm) 16 1m Xray (0.1 nm) 10 6 10 Earth@10GHz 2 1 10 Ω 12 10 A 8 1 10 8 10 4 2 10 4 0 10 3 10 0 10 8 10 10 10 12 10 14 10 16 10 18 10 20 10 2 4 6 22 10 10 10 10 D WINLAB C. Rose DIMACS Storage 3/24/04
✆ � � � ✁ � ✆ ✁ � � ✆ � � � ✁ � ✆ � Write Not Radiate 17 Is Radiation Better for Broadcast? Radiation illuminates many matter penalty 3 stars (LY) 3 Milky Way stellar density 6 4 10 Spherical galaxy, isotropic radiation, Arecibo-Arecibo 10 4 LY: 2 10 10 stars (but Ω 10 28 ) R 7 10 6 LY: 2 10 16 stars (but Ω 10 32 ) R 7 No, inscribed matter still wins! WINLAB C. Rose DIMACS Storage 3/24/04
� � � � � � � ✁ � � ✁ � � ✁ Write Not Radiate 18 Does Inscription Energy/Speed Eat Budget? Matter Inscription/Readout Energy and Time – Landauer said it can be reversible and abitrarily fast Empirical energy calc: – 60000 ATP/second for 20 minutes: 4639 Kbase of E-coli 20 J per ATP molecule – 8 10 1 . 19 J bit – 6 2 10 17 J bit 1 . – E at earth escape: 1 68 10 Construction energy not a problem WINLAB C. Rose DIMACS Storage 3/24/04
� ✆ ✆ � � � � � ✆ ✆ � � � � � ✆ ✆ � ✁ � Write Not Radiate 19 Radiation Needs Repetition 10 9 per year Civilization Birth Rate: α 1 10 8 per year Civilization Extinction Rate: β 1 Φ Success criterion 0 1 Now many repetitions N (optimally placed)? Φ 0 99 N 2000 Φ 0 9999 N 200 000, WINLAB C. Rose DIMACS Storage 3/24/04
� � � � � Write Not Radiate 20 Delivery Methods Big rock? Dust? Embedded dust & rock (comet)? Probe (Bracewell) Onward toward lunatic fringe WINLAB C. Rose DIMACS Storage 3/24/04
✆ � � � ✆ � � � ✆ � ✁ ✁ � ✆ � ✁ Write Not Radiate 21 Delivery Methods (more detail) Need exhaust braking c δ gIsp Energy penalty (excess mass): e I sp Specific Impulse – Chemical: 10 2 – Nuclear Electric: 10 4 – Fusion: 10 6 000, δ 20 1000 penalty 4 6 I sp δ 10 6 100 or I sp 2000 penalty 4 4 WINLAB C. Rose DIMACS Storage 3/24/04
� � � � ✁ � Write Not Radiate 22 Cosmic Insults Insults: – High energy particle bombardment – Heating (diffusion) – Ion tracks, dislocations, subatomic cascades Shielding: – 10 million years at 10% bacteria viability: 3 m radius rock 3 density) (3g cm 10 6 penalty – 3 4 Clever Composition, Coding and Correction: – ??????? WINLAB C. Rose DIMACS Storage 3/24/04
� � � � � Write Not Radiate 23 PUNCHLINES Inscribed matter messaging is NOT ridiculous Inscribed matter messaging might often be PREFERRED Questions for storage types: – General theory of inscribed matter storage? – Composition and Coding for survivability? – Ease of decoding (obviousness)? Learn more: http://www.winlab.rutgers.edu/ crose/cgi-bin/cosmic4.html WINLAB C. Rose DIMACS Storage 3/24/04
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