NSCI 314 LIFE IN THE COSMOS 1 INTRODUCTION THE SCIENTIFIC METHOD NUMBERS AND UNITS MOTION FORCES AND ENERGY MATTER AND LIGHT Dr Karen Kolehmainen Department of Physics CSUSB COURSE WEBPAGE http physics csusb edu karen EXTRATERRESTRIAL LIFE Defined as life beyond the earth earth includes on the surface below the surface in oceans and lakes and in the atmosphere This could be life on another planet or perhaps some other body a moon smaller object that orbits around a planet some other small object like an asteroid or comet a star some other object a neutron star out in space not on any object EXTRATERRESTRIAL LIFE Level of advancement or complexity Could be technologically advanced like aliens in science fiction Could be intelligent but not technologically advanced Could be complex but not very intelligent like terrestrial animals or plants Could be very simple something like terrestrial bacteria Similarity to life on earth Almost certainly won t be identical May be VERY different Need a definition of life ARGUMENTS FOR THE EXISTENCE OF EXTRATERRESTRIAL LIFE WE DON T THINK THERE IS ANYTHING UNUSUAL ABOUT THE EARTH THE SUN IS AN ORDINARY STAR ONE OF ABOUT 400 BILLION IN THE MILKY WAY GALAXY THE MILKY WAY GALAXY IS AN ORDINARY GALAXY ONE OF AT LEAST A TRILLION IN THE UNIVERSE PLANETS ARE KNOWN TO ORBIT MOST STARS SOME OF THESE PLANETS ARE PROBABLY SIMILAR TO THE EARTH WE THINK LIFE CAN GET STARTED EASILY IF THE CONDITIONS ARE RIGHT LIFE ON EARTH CAN SURVIVE UNDER A WIDE VARIETY OF CONDITIONS EXPERIMENTS SHOW THAT THE MATERIALS FROM WHICH LIVING THINGS ARE MADE FORM EASILY LIFE DEVELOPED VERY EARLY IN THE HISTORY OF THE EARTH THEREFORE IT WOULD PROBABLY ALSO DO SO ANYWHERE ELSE WITH SIMILAR CONDITIONS ARGUMENTS AGAINST THE EXISTENCE OF EXTRATERRESTRIAL LIFE MAYBE THE EARTH IS UNUSUAL IN WAYS THAT WE DON T FULLY APPRECIATE WE HAVE DISCOVERED NO REAL EVIDENCE FOR EXTRATERRESTRIAL LIFE THERE IS NO GOOD EVIDENCE THAT EXTRATERRESTRIALS HAVE EVER VISITED EARTH WE HAVE NOT RECEIVED ANY RADIO OR OTHER SIGNALS THAT ARE OBVIOUSLY THE RESULT OF AN EXTRATERRESTRIAL CIVILIZATION SPACECRAFT VISITING SEVERAL OTHER BODIES IN OUR SOLAR SYSTEM HAVE FOUND NO LIFE OUR APPROACH BRUSH UP ON SAME BASIC SCIENCE CONCEPTS STUDY ASTRONOMY TO FIND OUT WHAT TYPES OF OBJECTS MIGHT PROVIDE SUITABLE ENVIRONMENTS FOR LIFE AND HOW COMMON THESE ENVIRONMENTS ARE LIKELY TO BE STUDY BIOLOGY TO LEARN ABOUT THE ORIGIN AND EVOLUTION OF LIFE ON THE EARTH THE ONLY EXAMPLE OF LIFE WE KNOW ABOUT USE THIS KNOWLEDGE TO ESTIMATE HOW LIKELY WE ARE TO SUCCEED IN FINDING EXTRATERRESTRIAL LIFE STUDY TECHNOLOGICAL POSSIBILITIES FOR DISCOVERING EXTRATERRESTRIAL LIFE AND OR COMMUNICATING WITH EXTRRATERRESTRIAL CIVILIZATIONS THINGS TO KEEP IN MIND REMEMBER THAT OUR ESTIMATES OF HOW COMMON LIFE MIGHT BE WILL BE MOST VALID WHEN APPLIED TO LIFE SIMILAR TO OUR OWN THE EXISTENCE OF EXOTIC AND UNFAMILIAR LIFE FORMS WILL BE MORE DIFFICULT TO PREDICT HOWEVER THIS DOESN T MEAN THAT ANYTHING GOES WE HAVE STRONG EVIDENCE THAT THE LAWS OF PHYSICS ARE UNIVERSAL APPLY CRITICAL THINKING SKILLS AT ALL STAGES BE SKEPTICAL OF OUTRAGEOUS CLAIMS THE SCIENTIFIC METHOD 1 2 3 4 5 6 7 ASK A QUESTION MAKE OBSERVATIONS MAKE A HYPOTHESIS A CONCEPTUAL AND OR MATHEMATICAL FRAMEWORK FOR UNDERSTANDING THAT IS CONSISTENT WITH THE KNOWN FACTS USE THE HYPOTHESIS TO PREDICT THE RESULTS OF EXPERIMENTS CONDUCT THE EXPERIMENTS IF THE EXPERIMENTAL RESULTS DISAGREE WITH THE HYPOTHESIS REPLACE OR MODIFY THE HYPOTHESIS AND REPEAT THE PROCESS IF EXPERIMENTAL RESULTS AGREE WITH THE HYPOTHESIS CONTINUE WITH MORE EXPERIMENTS TO DOUBLE CHECK THE HYPOTHESIS THE SCIENTIFIC METHOD A SINGLE EXPERIMENTAL FACT THAT DISAGREES WITH THE PREDICTIONS OF A THEORY OR HYPOTHESIS WILL DISPROVE THAT HYPOTHESIS THIS DISTINGUISHES SCIENCE FROM PSEUDOSCIENCE IN CONTRAST A HYPOTHESIS CAN NEVER BE PROVEN BEYOND A SHADOW OF DOUBT IT IS POSSIBLE THAT SOME FUTURE EXPERIMENT WILL DISPROVE THE HYPOTHESIS OR THAT ANOTHER HYPOTHESIS THE RIGHT ONE CAN EXPLAIN THE SAME EXPERIMENTAL FACTS THE BEST WE CAN DO IS TO ACCUMULATE MORE AND MORE EVIDENCE THAT IS CONSISTENT WITH THE HYPOTHESIS IN WHICH CASE IT EVENTUALLY BECOMES A THEORY OR A LAW IF TWO HYPOTHESES CAN EXPLAIN THE SAME EXPERIMENTAL FACTS WE PREFER THE SIMPLER HYPOTHESIS OCCAM S RAZOR LARGE NUMBERS 1 THOUSAND 1 000 103 10 x 10 x 10 103 SECONDS IS ABOUT 17 MINUTES OUR LECTURE LASTS ABOUT 6600 SECONDS 1 MILLION 1 000 000 106 10x10x10x10x10x10 106 SECONDS IS ABOUT 12 DAYS 1 BILLION 1 000 000 000 109 109 SECONDS IS ABOUT 32 YEARS AVERAGE HUMAN LIFETIME IS ABOUT 2 5 BILLION SECONDS 1 TRILLION 1 000 000 000 000 1012 1012 SECONDS IS ABOUT 32 000 YEARS METRIC UNITS Distance or Length measured in meters m or kilometers km 1 km 1000 m 1 m about 39 inches a little over 3 feet 1 km about 0 62 miles Mass measured in grams g or kilograms kg 1 kg 1000 g 1 kg corresponds to about 2 2 pounds Time measured in seconds s SPEED DISTANCE AND TIME SPEED DISTANCE TIME Example An object that travels a distance of 6 meters m in a time of 3 seconds s has an average speed of 2 meters per second m s Note that speed has units of distance time for example m s km hr mi hr DISTANCE SPEED x TIME TIME DISTANCE SPEED SPEED OF LIGHT Light always travels at the same speed c through a vacuum empty space c 300 000 km s 3 x 105 km s Light travels 300 000 km in 1 second How far does light travel in a year 300 000 km s X 60 s min X 60 min hr X 24 hr day X 365 days year 9 500 000 000 000 km 9 5 X 1012 km SPEED OF LIGHT DISTANCE LIGHT TRAVELS IN ONE YEAR 9 500 000 000 000 km 9 5 x 10 12 km ONE LIGHT YEAR LY SPEED OF LIGHT 1 LIGHT YEAR 1 YEAR EXAMPLE How long a time does it take light to reach us from a star located 200 LY away ANSWER 200 years ACCELERATION A CHANGE IN THE SPEED AND OR DIRECTION OF MOTION OF AN OBJECT OVER TIME THIS INCLUDES SPEEDING UP SLOWING DOWN CHANGING DIRECTION OF MOTION CHANGING BOTH SPEED AND DIRECTION IF AN OBJECT IS NOT ACCELERATING HAS AN ACCELERATION OF ZERO IT MUST BE MOVING AT A CONSTANT SPEED AND IN A STRAIGHT LINE IT COULD BE AT REST AND STAYING AT REST THIS MEANS ITS SPEED IS ZERO AND IS REMAINING ZERO MOTION AND FORCES A FORCE IS A PUSH OR PULL A FORCE IS DESCRIBED BY HOW STRONG OR WEAK IT IS AND BY ITS DIRECTION IF SEVERAL FORCES ACT ON AN OBJECT THEY COMBINE TO PRODUCE A NET FORCE OR TOTAL FORCE EXAMPLE IF TWO EQUALLY STRONG FORCES ACT IN OPPOSITE DIRECTIONS THEY COMBINE TO PRODUCE A NET FORCE OF ZERO LIKE A TUG OFWAR BETWEEN TWO EQUALLY STRONG TEAMS MOTION AND