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CA 6.02 Light Speed & Observation

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The effect of light speed on visual observation. Light as carrier of images. Time delay in image delivery.

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CA 6.02 Light Speed & Observation

  1. 1. © ABCC Australia 2015 new-physics.com SPEED OF LIGHT & OBSERVATION Cosmic Adventure 6.02 A & B
  2. 2. © ABCC Australia 2015 new-physics.com Cosmic Adventure 6.02A SPEED TO CARRY IMAGES
  3. 3. © ABCC Australia 2015 new-physics.com The Greatness of being Constant Why is the finiteness and constancy of the speed of light so important to us? Being of constant speed, the various colours will come to our eyes simultaneously so there will be no mixing-up. The images will also come to us in the proper chronological order, one after the other. The earlier events will come earlier and the later one will come after, otherwise the universe will look totally different.
  4. 4. © ABCC Australia 2015 new-physics.com Image CarriersThese visual phenomena are possible and natural because our vision of this universe depends on the finiteness and constancy of the speed of light in carrying images to us.
  5. 5. © ABCC Australia 2015 new-physics.com Emission or Reflection of Light Every object in this universe either emits or reflects light. Reflection Emission
  6. 6. © ABCC Australia 2015 new-physics.com Light & Vision We can see an object because its light brings the images to our eyes. This means that light is the visual image carrier in our lives.
  7. 7. © ABCC Australia 2015 new-physics.com Vison in classical optics The visual appearance of an object is determined by the light from all points on the objects that arrives simultaneously at where the eye is.
  8. 8. © ABCC Australia 2015 new-physics.com . . . Remembering that the images are not transmitted by a single photon, but by trillions of them. The more they are, the higher resolution we’ll get. Images – The Work of Multitude
  9. 9. © ABCC Australia 2015 new-physics.com Vision Science Vision is a human perception. It is a very complex science and no one has figured out the full picture.
  10. 10. © ABCC Australia 2015 new-physics.com Automatic Interpretation But we only need to know the simple fact that our eyes are there to automatically interpret the light coming to our eyes and into the images in our minds. So we don’t have to know the detail of the optical science and only concentrate on the simpler process of how images come into our eyes.
  11. 11. © ABCC Australia 2015 new-physics.com Our eyes intercept the light and interpret them as the images in our mind. This is how we can see.
  12. 12. © ABCC Australia 2015 new-physics.com In all scales The process is universal. It takes place big and small, whether of material bodies or environment, from a microbe to a galaxy.
  13. 13. © ABCC Australia 2015 new-physics.com Image Carriers In such a way, light is serving as the carrier of images, bringing us the enjoyment of vision.
  14. 14. © ABCC Australia 2015 new-physics.com TIME DELAY IN IMAGE DELIVERY Cosmic Adventure 6.02B
  15. 15. © ABCC Australia 2015 new-physics.com Speed of Light too Fast Light travels at a speed of about 300,000,000 meters per second. This is an astronomical figure. There is nothing in our daily life that comes anywhere close to it. For example, the speed of sound is only 343.2 meters per second; even supersonic speeds of 5 or six times greater than the speed of sound are only about 1,500 meters per second. 300,000,000 meters per second 1,500 meters per second.
  16. 16. © ABCC Australia 2015 new-physics.com 26.8 70 100 770 13,000 66,641 671,000,000 0.1 1 10 100 1000 10000 100000 1000000 Light Earth Jet Sound Baseball Cheetah Fastest Runner Speed in miles per hourSpeed in km per hour 109,870,000 107,244 20,921 1,239 161 113 43 Comparison of Some Speed Samples
  17. 17. © ABCC Australia 2015 new-physics.com Light Takes Time to Travel But no matter how fast light travel, light still needs time to cover a distant, no matter how small the distance is. For an object one meter away, light from it takes 3.3 nanoseconds (10-9 second) to reach our eyes; for an object one kilometer away, light from it takes 3.3 microseconds to reach our eyes. (A microsecond is a unit of time equal to one millionth or 10-6 of a second.)
  18. 18. © ABCC Australia 2015 new-physics.com Delayed Vision This means that by the time light from an object reaches our eye, some length of time must have elapsed. This is the universal delay of image delivery. 𝑇𝑖𝑚𝑒 = ∆𝑡
  19. 19. © ABCC Australia 2015 new-physics.com In the astronomical scale, the difference is more appreciable. Take for example, the moon is 384,400 km away from the earth and the speed of light is 299,799 km per second. The time taken for its light to reach earth is: 384,400 𝑘𝑚 299,799 𝑘𝑚/𝑠𝑒𝑐𝑜𝑛𝑑 = 1.28 𝑠𝑒𝑐𝑜𝑛𝑑 About 1.28 𝑠𝑒𝑐𝑜𝑛𝑑
  20. 20. © ABCC Australia 2015 new-physics.com The light from the sun, which is about 3 × 1011 metres away, will take light to travel about 8 minutes in space before reaching earth. This means that if the sun were suddenly to go dark, it would take over eight minutes before we notice the darkening. About 8 minutes
  21. 21. © ABCC Australia 2015 new-physics.com Another example: The galaxy of Andromeda is 2,538,000 light years away from the earth. A light year is the time taken for light to travel in one year – covering about 9 trillion kilometers (about 6 trillion miles). This 2,538,000 light years is the time needed for its light to reach earth. 2,538,000 𝐿𝑖𝑔ℎ𝑡 𝑦𝑒𝑎𝑟𝑠
  22. 22. © ABCC Australia 2015 new-physics.com Remember how Römer discovered the speed of light due to the delay in time obvious in astronomical observation? Ole Römer Discovered the speed of Light Jupiter Io Earth moving towards Jupiter Io hides behind Jupiter and becomes invisible Earth moving away from Jupiter
  23. 23. © ABCC Australia 2015 new-physics.com Distance Distance Speed of light in vacuum (c): 3 × 108 m/s 10-9 s 10-1+ m Objects a foot away are seen as they were a nanosecond in the past. 10-8 s 100+ m Light speed delay across a human is about 5 nanosec. 10-7 s - 10-2 s 101+ m - 106+ m 10-1 s 107+ m Circle the earth in 1/10 s. | Geosync communication satellites. 100 s 108+ m 1.25 sec from moon. 101 s to 102 s 109+ m to 1010+ m 103 s 1011+ m 8 minutes from sun. 104 s to 107 s 1012+ m to 1015+ m 108 s to 1011 s 1016+ m 9 years (0.3 Gigasecond) from Sirius (108×2.7 s) 109 s 1017+ m to 1019+ m 1012 s 1020+ m 100 kyr (3 Terasecond) across galactic disk (1012×3 s) 1013 s to 1017 s 1021+ m to 1025+ m 1018 s 1026+ m 1/2 Exasecond (~15 Gyr) from edge of visible universe (1018×~1/2) 1027 m Current distance to edge (of Universe) Light-speed delay. Ref: Mitchell N Charity <mcharity@lcs.mit.edu>
  24. 24. © ABCC Australia 2015 new-physics.com Findings from Australian Space Academy “Distance communications are carried by electromagnetic radiation - commonly by radio waves, but increasingly by light. The speed of propagation of these carriers is about 300,000 kilometres per second - the speed of light (and all other electromagnetic radiation). While this is an incredibly high speed, it already causes problems in some of our day to day communication, and as we begin to contemplate interplanetary travel, we find that the finite or limited speed of light imposes serious limitations on our activities.” www.spaceacademy.net.au
  25. 25. © ABCC Australia 2015 new-physics.com Telephone Delay The delay caused by the speed of light can even be noticed here on Earth in long distance telephone calls. These called may have been routed over one or more space satellites. So delay between the speaker and the listener may be as long as over half a second.
  26. 26. © ABCC Australia 2015 new-physics.com Circuit Distance Delay Time HF link (UK-NZ) ~20,000 km 0.07 s (67 ms) Submarine cable(UK-NZ) ~20,000 km 0.07 s (67 ms) Geosat Link (US-Aus) ~80,000 km 0.25 s Earth-Moon 384,000 km 1.3 s Earth-Mars 55 - 378 million km 3 - 21 minutes Earth-Jupiter 590 - 970 million km 33 - 53 minutes Earth-Pluto ~5800 million km 5 hours Earth-Nearest Star ~9.5 million million km 4 years Communication Delay www.spaceacademy.net.au/spacelink/commdly.htm
  27. 27. © ABCC Australia 2015 new-physics.com Time & Distance Gap What we see are only images delivered to our eyes by light coming from a source some time ago. In general, there is always a time delay in messages which need light as a carrier, no matter how short the distance is between the observer and the observed. Observer Observed
  28. 28. © ABCC Australia 2015 new-physics.com 𝒄 So distant objects are all old ones at various times in the past.
  29. 29. © ABCC Australia 2015 new-physics.com TIME DELAY IN CLASSICAL PHYSICS & THE THEORY OF SPECIAL RELATIVITY To be continued on Cosmic Adventure 6.03

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