Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41NSCI 314LIFE IN THE COSMOS12 - WHERE TO SEARCH FOR LIFE OUTSIDE OUR SOLAR SYSTEM:“EXOTIC LIFE”ANDSUITABLE STARS AND PLANETSDr. Karen KolehmainenDepartment of Physics, CSUSBhttp://physics.csusb.edu/~karen/ADVANTAGES OF PLANETS AND LARGE MOONS FOR LIFECONDUCIVE TO CHEMISTRY (ATOMS COMBINING AND RECOMBINING TO FORM MOLECULES)PROVIDE A RELATIVELY STABLE AND PROTECTED ENVIRONMENT (AT LEAST IN MANY CASES)SMALL VARIATIONS IN ENVIRONMENTVARIETY OF INTERFACES BETWEEN LAND, OCEANS, AND ATMOSPHERELIFE IN LOCATIONS OTHER THAN PLANETS OR LARGE MOONS?SMALL MOONS, ASTEROIDS, ETC.–NO ATMOSPHERE - THEREFORE NO LIQUIDS, EXTREME TEMPERATURE VARIATIONS, AND NO PROTECTION AGAINST ULTRAVIOLET RADIATIONSTARS–TOO HOT FOR COMPLEX MOLECULES TO FORMNEBULAE (CLOUDS IN THE INTERSTELLAR MEDIUM)–LOW TEMPERATURE AND DENSITY  CHEMICAL REACTIONS PROCEED VERY SLOWLY  HARD TO IMAGINE COMPLEX MOLECULES FORMINGNEUTRON STARS??LIFE ELSEWHERE COULD HAVE:Very similar proteins and DNA sequences to us (if so, a common origin is likely)Same amino acids and genetic bases as us, but combined into different proteins and DNA sequences (common origin?)Amino acids and genetic bases, but not the same 20 amino acids and 4 or 5 bases as usDifferent monomers, (i.e., not amino acids and genetic bases), but still carbon-based polymers of some sortDifferent chemistry (silicon-based?)No chemistry at all! (exotic matter, or interactions other than electromagnetic)CHEMISTRY INVOLVES COMBINING ATOMS TO MAKE MOLECULES (INCLUDING MOLECULES BEING BROKEN APART INTO ATOMS, THEN ATOMS REARRANGING AND COMBINING INTO NEW MOLECULES)BASIS OF ALL LIFE ON EARTHBASIS OF ALL CARBON-BASED LIFEBASIS OF SILICON-BASED LIFE (IF POSSIBLE)HAPPENS BECAUSE OF ELECTROMAGNETIC FORCESFUNDAMENTAL FORCESMANY FORCES ARE ELECTROMAGNETIC FORCES.–ELECTRICAL FORCES HOLD ATOMS TOGETHER (ATTRACTION BETWEEN POSITIVELY CHARGED NUCLEUS AND NEGATIVELY CHARGED ELECTRONS).–ELECTRICAL FORCES HOLD ATOMS TOGETHER TO FORM MOLECULES. (ELECTRONS ARE TRANSFERRED OR SHARED BETWEEN ATOMS.)–ELECTRICITY AND MAGNETISM ARE CLOSELY RELATED - MAGNETISM IS CAUSED BY MOVING ELECTRIC CHARGES.–“CONTACT” FORCES ARE ELECTRICAL WHEN EXAMINED ON A MICROSCOPIC LEVEL.HOW MANY KINDS OF “FUNDAMENTAL” FORCES ARE THERE? WE THINK THERE ARE ONLY FOUR TYPES OF FUNDAMENTAL FORCES.FUNDAMENTAL FORCES(IN ORDER FROM STRONGEST TO WEAKEST)NAME RANGE EFFECTSSTRONG SHORT HOLDS NUCLEI OF ATOMS TOGETHERELECTROMAGNETIC LONG HOLDS ATOMS AND MOLECULES TOGETHERWEAK SHORT CAUSES BETA DECAY (TYPE OF RADIOACTIVE DECAY) AND SOME OTHER PROCESSESGRAVITY LONG HOLDS PLANETS, STARS, AND GALAXIES TOGETHERHOW ARE THE FUNDAMENTAL FORCES RELATED TO LIFE?ANY FORM OF LIFE THAT INVOLVES CHEMISTRY (ATOMS AND MOLECULES) IS BASED ON THE ELECTROMAGNETIC FORCE, BECAUSE THE ELECTROMAGNETIC FORCE IS RESPONSIBLE FOR HOLDING ATOMS AND MOLECULES TOGETHER. COULD LIFE BE BASED ON ONE OF THE OTHER FUNDAMENTAL FORCES INSTEAD? FOR THIS TO BE POSSIBLE, ONE OF THE OTHER FORCES WOULD HAVE TO BE ABLE TO HOLD TOGETHER MATTER IN SOME SORT OF COMPLEX (LOW ENTROPY) ARRANGEMENT.IF SO, LIFE WOULD BE VERY DIFFERENT FROM TERRESTRIAL LIFE.HOW ARE THE FUNDAMENTAL FORCES RELATED TO LIFE?COULD LIFE BE BASED ON ONE OF THE OTHER FUNDAMENTAL FORCES (NOT ELECTROMAGNETIC)? –PROBABLY NOT THE WEAK FORCE, BECAUSE IT DOESN’T HOLD ANYTHING TOGETHER.–PROBABLY NOT THE GRAVITATIONAL FORCE, BECAUSE IT IS SO WEAK THAT IT CAN ONLY HOLD TOGETHER VERY LARGE OBJECTS LIKE PLANETS AND STARS. FOR INTERACTIONS BETWEEN SMALLER AMOUNTS OF MATTER, GRAVITY IS SO WEAK THAT WE CAN IGNORE IT.–HOW ABOUT THE STRONG FORCE?STRONG INTERACTION LIFE?STRONG INTERACTIONS HOLDS PROTONS AND NEUTRONS TOGETHER IN ATOMIC NUCLEIORDINARY NUCLEI AREN’T VERY COMPLEX OR ORDERED, BUT…NEUTRONS CAN FORM COMPLEX ARRANGEMENTS (HELD TOGETHER BY STRONG FORCE) ON THE SURFACE OF A NEUTRON STAR.COULD THESE BE COMPLEX ENOUGH TO BE CONSIDERED LIFE?? WE DON’T KNOW, BUT IF SO,–SIZE ~ 0.00000000001 CM–STRONG INTERACTIONS OCCUR VERY QUICKLY (VERY SHORT TIMESCALES) – THEREFORE LIFETIME OF INDIVIDUAL ORGANISM IS ~ 0.000000000000001 SEC–COMMUNICATION VIA GAMMA RAYS?–HIGHLY RECOMMENDED SCIENCE FICTION: “THE DRAGON’S EGG” BY ROBERT FORWARDSEARCHING FOR LIFE IN OTHER SOLAR SYSTEMSWE WILL TAKE A CONSERVATIVE APPROACH. WE WILL CONSIDER ONLY LIFE THAT IS BASED ON THE ELECTROMAGNETIC INTERACTION, i.e., ATOMS AND MOLECULES. FURTHERMORE, WE WILL ONLY CONSIDER LIFE THAT USES CARBON-BASED CHEMISTRY AND USES WATER AS ITS LIQUID SOLVENT. (IGNORE POSSIBILITY OF “EXOTIC LIFE,” SUCH AS LIFE THAT USES A LIQUID SOLVENT OTHER THAN WATER, SILICON-BASED LIFE, OR LIFE BASED ON THE STRONG FORCE.)–THEREFORE CONSIDER ONLY EARTH-LIKE PLANETS (OR LARGE MOONS) WITH LIQUID WATER.–IF EXOTIC LIFE CAN EXIST, THEN LIFE MAY EXIST IN A LARGER RANGE OF LOCATIONS AND BE MORE COMMON THAN WHAT WE WILL ESTIMATE.PROPERTIES OF A PLANET THAT IS SUITABLE FOR LIFE1. RELATIVELY LARGE ABUNDANCES OF CARBON, NITROGEN, AND OXYGEN (PLUS TRACE AMOUNTS OF HEAVIER ELEMENTS)2. NOT NEAR A SITE OF COSMIC VIOLENCE3. ROCKY PLANET - SOLID SURFACE4. MASSIVE ENOUGH TO RETAIN A REASONABLY DENSE ATMOSPHERE 5. CORRECT TEMPERATURE RANGE FOR LIQUID WATER (SOLVENT)6. STABLE ENVIRONMENT FOR SEVERAL BILLION YEARS (TIME NEEDED ON EARTH FOR ADVANCED LIFE FORMS TO EVOLVE)ELEMENTAL ABUNDANCESHYDROGEN AND HELIUM (BUT NO HEAVIER ELEMENTS) ARE PRODUCED SHORTLY AFTER THE BIG BANG (DURING THE FIRST FEW MINUTES OF THE UNIVERSE).HEAVIER ELEMENTS ARE PRODUCED VIA FUSION IN STARS AND RETURNED TO THE INTERSTELLAR MEDIUM VIA PLANETARY NEBULAE AND SUPERNOVAE.HEAVIER ELEMENTS ARE INCORPORATED IN NEW STARS (AND THEIR PLANETARY SYSTEMS) FORMED FROM THE ENRICHED INTERSTELLAR MEDIUM.ELEMENTAL ABUNDANCESTHEREFORE, PLANETARY SYSTEMS AROUND YOUNGER STARS CONTAIN LARGER ABUNDANCES OF HEAVY ELEMENTS (ANYTHING HEAVIER THAN H AND He) THAN PLANETARY SYSTEMS OF OLDER STARS.THUS PLANETS THAT CONTAIN ELEMENTS NECESSARY FOR LIFE ARE MORE LIKELY TO BE FOUND ORBITING YOUNGER STARS THAN OLDER STARS.PLANETS MAY NOT EVEN BE ABLE TO