Waves All Around: the Electromagnetic Spectrum in Everyday Life

Karl Scheidt Department of Chemistry

Great Minds, Great Ideas Series Finale

Part I Overview • Introduction to the electromagnetic spectrum (waves? what waves?) • Basics, background and history • EM spectrum in our lives • Societal impact & questions • Discussion/Conclusion

Disclaimer: I am not a physicist or electrical engineer!

• How much of the EM spectrum can we see? • Who discovered this stuff? • Why should I care? • Where is the EM spectrum and who “owns” it? • What does the Titanic have to do with the EM spectrum? • What does“radiation” do to cancer?

• Maiden voyage of RMS Titanic • Received ice warnings (how??) that were discounted. • Hits iceberg at 11:40 PM...sinks by 2:30 AM. • Sends “C.Q.D.” signal 6x (how?)- Marconi’s earlier version of S.O.S. Then switches to S.O.S. by 12:45 AM. • Olympic (500 mi away), Baltic and Carpathia and others rush to coordinates- ~800 saved. • EM spectrum critical to long distance communication. How did this come about?

25 year old 21 year old John (Jack) G. Phillips Harold Bride died on Titanic, not recovered survived

• G. Marconi invents the radio telegraph ~1895 (20 yrs old). • awarded the 1909 Nobel Prize in Physics • Father of wireless communication. • RMS Titanic “wireless operators” (J. Phillips and H. Bride) employed by Marconi Comm. Co., not White Star Line. • “Those who have been saved, have been saved through one man, Mr. Marconi...and his marvelous invention,” British Postmaster General during Court of Inquiry, 1913. • The closing of one chapter and beginning of another in human technology.

• The wave/frequency equation: where c = speed of light • higher frequency = smaller wavelength • lower frequency = longer wavelength all rights reserved Introduction: Basics • The EM spectrum is composed of waves • These waves have energy. • Similar to sound waves, but different:

• Have 2 components: magnetic & electrical

today’s lecture

If the entire electromagnetic spectrum stretched for 3,000 miles from Los Angeles to New York, our eyes only detect an amount equal to the length of one of our arms (the visible spectrum). All the rest of it (99.99999%) is lost from our everyday awareness.

• James Clerk Maxwell (E and M are connected) • Max Planck (black body radiation) • Albert Einstein (photoelectric effect) • G. Marconi (“father of radio”) • Wilhelm Rontgen (discoverer of X-rays) • Philo Farnsworth/David Sarnoff (television) • Many others...

• Formulated equations that describe electricity, magnetism and optics as “manifestations of the same phenomenon”, i.e., the electromagnetic field. • One of the great discoveries/developments in all of science. • In 1865, he demonstrated that electric and magnetic fields travel through spaces as waves at the speed of light. • Proposed (correctly) that light is composed of both E & M fields. • On par with Newton and Einstein in terms of scientific impact. Laid the ground work for all EM discoveries/devices.

Maxwell-Faraday eq. (law of induction)

E = electric field, B is magnetic field: a time-varying magnetic field is always accompanied by a spatially-varying electric field, and vice-versa • Maxwell-Faraday equation: Varying a magnetic field creates (induces) an electric field. The basis of all electric motors.

all rights reserved Electric Motors • Thanks to Faraday and Maxwell, we can interconvert magnetic and electric fields! • Motors: Applied electric fields can rotate a shaft in a magnetic field (motors). • Power: Turbines (turned by water, steam or wind) create magnetic field disturbance that generates electric field.

all rights reserved Max Planck • Theoretical physicists (Nobel Prize in 1918) • Father of quantum theory • Started working on “black body radiation” by commission from electric companies. • BBR: EM waves (radiation) emitted by source at constant temperature. • Created equation that fit the experimental data of BBR by assuming the energy was “quantized”. Radical notion! • Frequency is proportional to temperature The temperature of a Pāhoehoe lava flow can be estimated by observing its color. The result agrees well with measured temperatures of lava flows at about 1,000 to 1,200 °C (1,832 to 2,192 °F all rights reserved Albert Einstein

• Discovered the photoelectric effect (1905) for which he received the Nobel Prize in physics (1921). • Needed to invoke “quantization” of EM radiation to explain this phenomenon. Inspired by Planck.

• Energy of the photons = energy of electrons ejected. Electrons are in speciﬁc energy states. • Basis of solar energy: light = electric current

all rights reserved Radio • Information, such as sound, is carried by systematically changing (modulating) some property of the radiated waves, such as their amplitude, frequency, phase, or pulse width. • Both Edison and Tesla were in ﬁerce competition in late 1890’s for wireless transmission of energy (radio waves). • Marconi the ﬁrst to successfully build system of transmitting signals for long distance. (1905) • The overall process:

all rights reserved Radio • Wavelength = 1 mm to 1 km. Freq. 300 GHz-3Hz. Very little energy. • AM (amplification modification) developed first. Then FM (frequency modulation). • FM stations now predominate normal radio listening. AM signals have much more range (>1000 miles).

all rights reserved Radar • Radar: RAdio Detection And Ranging • 1886: German physicist H. Hertz demonstrates that radio waves are reﬂected by solid objects. • US Navy investigates in the early 1900s... RADAR is born. Major world wide conﬂict necessary to prompt development.

all rights reserved Battle of Britain • Summer/Fall of 1940- Germans initiate major aerial attack/bombing campaign to invade & defeat England. • Surprise attacks early on were devastating. A NEW tool was necessary to save lives and England. • “Chain Home” radar defenses were established for early warning of Luftwaffe attacks. • A. Loomis and Tuxedo Park lab was instrumental in making key radar advances (range, precision) which saved England and possibly WWII.

Suggested Reading: TUXEDO PARK: A Wall Street Tycoon and the Secret Palace of Science That Changed the Course of World War II

all rights reserved Weather Tracking • During World War II, military radar operators noticed noise in returned echoes due to rain, snow • Radar is major advance in weather tracking and forecasting. Now critical in tornado and hurricane predictions. • Doppler radar provides information about MOVEMENT of targets as well as position (change in frequency).

• The change in frequency of wave for an observer relative to a MOVING source (sirens, trains). • Can be sound waves, radio waves (RADAR), etc.

not moving < speed of sound > speed of sound

• Radio wave transmissions in 54-890 MHz frequency band. (VHF & UHF) Now all digital signals & HD. HD means more information sent per “cycle”- more pixels. • First public demonstration in Berlin in 1931- 1936 Olympic games were broadcast live in Berlin to public. • Philo Farnsworth (1906-1971) was major TV pioneer- inventor of electric television. He battled RCA (and David Sarnoff) for patent priority and technology for decades. • “Cable” now major player vs. over the air (OTA). • Satellite TV use 950-2150 MHz frequencies. Satellites are in geostationary orbits (~23,000 mi above equator).

Suggested Reading: The Last Lone Inventor: A Tale of Genius, Deceit, and the Birth of Television Evan Schwartz

“The fascinating inside story of how this eccentric loner invented television and fought corporate America." —Walter Isaacson, biographer, past chariman of CNN

• In WWII, military used hand-held radio transceivers. • 1960s-70s: Frequency “reuse” and switching of call (handoff) from one tower to multiple receivers developed. “Cell” is a land area covered by a transceiver (base station). • April 1973, Martin Cooper of Motorola makes 1st mobile telephone call (to J. Engel at Bell Labs). 1 kg with 10 h charge for 30 min (analog signal, 1G). • 4G systems now all digital and avoids circuit switching. • Has clearly changed how the world communicates (Facebook, Twitter, etc). How is all this information handled???

• CDMA: Code division multiple access. • Each call gets a unique “code” • Information is spread over all available frequencies. “Multiple” means that >1 user can use the same frequency. • CDMA greatly increases practical “bandwidth”, range of frequencies available to transmit speciﬁc information. • Operates in the 800 MHz and 1900 MHz bands. • Europe uses GSM (Global System for Mobile comm) protocol. Uses single frequency that is very narrow.

all rights reserved WiFi • “Wireless Fidelity” Radio range (2.4 GHz band). • Completely changed consumption of the internet. • 802.11 technology developed from 1985 FCC ruling for NCR corp. to develop wireless cashier systems (WaveLAN). • Father of WiFi: Dutch engineer Vic Hays who negotiated the standard of the protocol with the Institute of Electrical and Electronics Engineers (IEEE). • WiFi has limited range (35-100 m) and consumes more power than Bluetooth. • ENCRYPT YOUR WIFI NETWORKS! Use WPA2, not WEP

all rights reserved Microwave Ovens • Bombards food with microwaves- excites/ heats water molecules. (Frequency of 2.45 GHz, 122 mM wavelength). • Discovered accidentally in 1945 by Raytheon. Patent ﬁled soon afterward... • First unit “Radarange”: (installed on US Naval ship): 340 kg, 6 ft tall and $60,000. Had to be water cooled. • Depth of wave penetration depends on food type and frequency of energy. Does not heat from inside out. • Why doesn’t your microwave disrupt your WiFi?

all rights reserved Infrared • 1 mm to 700 nm wavelength (430 THz to 300Gz) • Discovered by William Herschel in 1800 • Used in • Night vision, surveillance devices (human heat). • Art history • Astronomy • Remote controls!

• How do we see visible waves?

• Energy from light: like photoelectric effect!

the rest of ...is extremely the story... complicated

• Large effort to mimic photosynthesis. • Use light to “split” H2O to H2 and O2. H 2 then used for fuel. • Dept. of Energy has large programs around the country (including NU). • Solar energy: Use photovoltaic cells made from silicon to generate electricity from light. Current “best” efﬁciencies are ~30%, but require xt. pure Si and metals.

• Light Amplification by Stimulated Emission of Radiation • “Coherent” light- single focused frequency. Can be very short pulses (femtosecond, 10-15) 1015 sec = 31.6 M years! • 1953: the MASER was developed (microwave). ~1958, Bell Labs and Columbia Univ. disclosed lasers with IR wavelengths. 28 yr lawsuit on patent fillings... • Used in DVD players, laser printers, bar code scanners, surgery, distance ranging, scientific research, weapons? • Huge power range from laser pointers (1 mW) to CO2 lasers for industrial metal cutting (3000 W).

• Wavelength: 10-400 nm. Frequency: 1014 to 1016 • Sun emits powerful UV radiation. Ozone layer block most wavelengths (UV A and B: 400-280 nm) • Sunblock has molecules that absorb these waves. UV radiation causes DNA damage in your skin. • Birds, ﬁsh and insects “see” near UV (400 nM) that we cannot!!

• Wavelength: 0.1-1 nm. Frequency: 1016 to 1019 Discovered by Wilhelm Rontgen in 1895 (1st Nobel Prize in Physics in 1901) • Found almost immediate use in medicine (request by McKinley aide to Edison after 1901 shooting). • Serious energy associated with X-rays- can penetrate soft tissue. Early uses were popular without regard for safety. • Can be used to determine atomic connectivity. • Still used by TSA to scan baggage.

• Wavelength: 10-11 m (pm). Frequency: 1019 or greater. Can penetrate through inches of lead. Deadly. • First observed in decay of radioactive elements: very high energy & very dangerous. Typically can destroy living cells by ionizing anything it hits (DNA). • Gamma “decay” typical in nuclear explosions. • “Gamma Knife”: can be used to destroy speciﬁc tissue (tumors), but precision is critical. • Used in astronomy to map high energy bodies (pulsars, quasars, black holes). 2006 supernova near Leo was 12 B light years from earth- just 1.6 B yrs after Big Bang.

all rights reserved Cancer Treatment • Radiation therapy relies on EM to deliver energy to tumors. (usually X-ray and gamma) • Used for over 100 years (Rontgen). With computed tomography (CT) in 1971, a real “map” could be used to pin point tumors with more accuracy. • “Ionizing” energy destroys DNA of cells in path of EM waves. Can be very focused or whole body. Can also be delivered by internal sources placed near/in the tumor. • Depending on dose, radiation can have signiﬁcant side effects.

http://www.encognitive.com/node/10696 all rights reserved MRI: New Medicine • Magnetic Resonance Imaging. In a strong magnetic field, energy polarizes hydrogen atoms of water at a specific radio wave frequency. • When these molecules “relax”, the decay is sensed by coils around the subject. • Completely changed medicine in late 20th and early 21st century: 25,000 scanners world wide. • Serious controversy in its discovery/application. 2006 Nobel Prize in Medicine given to Laterbur and Mansfield

• Federal Communications Commission: regulates interstate and international communications by radio, TV, wire, satellite and cable. • Independent agency formed by Comm. Act of 1934. Funded entirely by regulatory fees (CoI?). 1900 employees. • Five commissioners conﬁrmed by Senate for 5 yr terms with one designated by President as chair (Thomas Wheeler). • Issues: Net neutrality, NSA wiretaping, proprietary standards, spectrum auctions.

• Damage from EM is directly related to how much power each wave region has. • FCC, IEEE, Int. Commission on non-ionizing radiation protection (ICNIRP) involved in setting standards. • Do cell phones cause cancer? Only known effect at this time is radio wave heating (NCI). Radio waves are non-ionizing. see, http://www.cancer.gov/cancertopics/factsheet/Risk/cellphones • FDA: No no known harmful side-effects associated with temporary exposure to the strong magnetic ﬁeld used by MRI scanners (2012). No metals or pacemakers!!!!! • UV, X-rays, gamma rays can all cause damage. all rights reserved New Horizons

• Wireless charging • Real-time brain imaging • Functional prosthetic limbs controlled by thought • Electric cars (Tesla, Leaf) • Flexible/more efﬁcient solar panels

all rights reserved For Discussion • What does the future hold for EM spectrum use? • Should government be more involved? FCC killed ATT/T- mobile merger, but approved NBC/Comcast. • Can internet “neutrality” be maintained? • Who “owns” the airwaves? FCC, big biz and speculation rampant.

To drive critical and high impact advances in 21st century medicine with small molecules. Currently working with NU Development (Kelly Glenn) to build endowment for therapeutic discovery @ Northwestern including seed research, fellowships, & student internships.

Please contact me if you are interested in learning more!