ask and it will be given to you
“…ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you. ”
宇宙有多大? p Sun: Distance from Earth 149, 600, 000 Km; Mass 333, 000 x earth; radius 109 x earth; rotation 25. 4 days at equator to 35 days near poles p 太陽系 p 銀河系 …
What is dark matter? ? Or maybe it’s easier to say what is NOT dark matters § not in the form of stars and planets that we see § not in the form of dark clouds of normal matter, matter made up of particles called baryons. Otherwise we would be able to detect it by their absorption of radiation passing through them. § not antimatter, because no such unique gamma rays that are produced when antimatter annihilates with matter. § not black holes. Black holes bend light passing near them, but we do not see enough lensing events to suggest that such objects to make up the required 25% dark matter contribution.
宇宙在膨脹--- 怎麼知道的? Red Shift Doppler effect 1929
What Is Dark Energy? More is unknown than is known. One explanation for dark energy is that it is a property of space. Albert Einstein was the first person to realize that empty space is nothing: One version of Einstein's gravity theory that contains a cosmological constant, makes a second prediction: "empty space" can possess its own energy. Because this energy is a property of space itself, it would not be diluted as space expands. As more space comes into existence, more of this energy-of-space would appear. As a result, this form of energy would cause the Universe to expand faster -- Unfortunately, no one understands why the cosmological constant should even be there, much less why it would have exactly the right value to cause the observed acceleration of the Universe. 真的有時間,空間嗎? 還是它只是一個概念?
狹義相對論 Special relativity 相對論 Theory of relativity 廣義相對論 General relativity 時間是甚麼? 時空是甚麼?
Space –time warp Light (no mass) is trapped
Time machine STEPHEN HAWKING: How to build a time machine By STEPHEN HAWKING Last updated at 10: 08 AM on 3 rd May 2010 Read more: http: //www. dailymail. co. uk/home/moslive/article 1269288/STEPHEN-HAWKING-How-build-time-machine. html#ixzz 11 M 4 Ny. Tpq “What is now proved was once only imagin’d. ”
particle wave Light --- wave or particle? Electron --- wave or particle?
Double slit experiments with light “waves” Patterns on the screen – waves “interference”
Double slit experiments with sand “particles”
Double slit experiments with atom “particles” 1. With only one slit open 2. With both slits open Not expected ! Interference pattern, center is a bright band
接下來在狹縫後裝上偵測器來偵測原子從哪個狹縫通過, 結果 1. 每次偵測到的原子都是整個原子,不是半個或一部份 的原子。 2. 偵測器只要打開偵測(have knowledge of which atom passing through, i. e. when we are looking), 就出現粒子的條紋,偵測器一關掉(no knowing of what happens when it pass through the two slits, i. e. when we are not looking)就出現波的條紋。 So the detector can somehow convert a ‘spread-out’ atom wave into a ‘localized’ atom particle The act of observation!! When we check, we alter the outcome!
The wave function Superposition of states v Mathematically in Schroedinger equation is a complex function (real part and imaginary part) v State of being v Probabilistic nature v The wave function spread out over all space What is the state of ‘existence’ in a particular moment in time?
Wave-particle duality
Do you believe in fate? Is the future preordained and destined to take place? Soulmate? I. Determinism The future can be determined if we have the complete knowledge of the present. Prediction of storm, prediction of the face of a dice, lottory… We are all made up of atoms. Under the law of interaction, our decisions are determined, then there is no meaning of “free will”. Though to make a prediction of a complicated system is almost impossible, it is still deterministic!. II. Indeterminism ‘fate’ as a scientific idea was proven to be false a century ago. Quantum unpredictability A fundamental feature of nature !! Identical situations can lead to different outcome! Einstein: God don’t play dice! Bohr: Einstein, stop telling God what to do!
Quantum entanglement 超光速 ? Matter waves
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