Planet Mercury | Space School NEPTUNE - SOUNDS FROM SPACE - NASA VOYAGER I - II RECORDINGS THINK ABOUT NATURE And up until the modern era, where we describe them in quantum mechanics, the laws also never changed. The laws lets us predict where the positions of the atoms will be at a later time, if we know the positions of all the atoms at a given moment. That's how we do physics and I call that the Newtonian Paradigm because it was invented by Newton. And behind the Newtonian Paradigm is the idea that the laws of nature are timeless; they act on the system, so to speak, from outside the system and they evolve from the past to the present to the future. If you know the state any time, you can predict the state at any other time. So this is the framework for doing physics and it's been very successful. The problem that I've identified—that I think is at the root of a lot of the spinning of our wheels and confusion of contemporary physics and cosmology—is that you can't just take this method of doing science and scale it up to the universe as a whole. Now some of this is not new.
Sound of the Sun Stjärnor och planeter (LättLäst) Stjärnor och planeter (LättLäst) Det finns en sol och 8 planeter i vårt solsystem. Planeterna snurrar runt solen i banor. Planeterna ligger i den här ordningen: Merkurius, Venus, Jorden, Mars, Jupiter, Saturnus, Uranus, Neptunus. Tidigare fanns en planet till. Den hette Pluto. Det är solens dragningskraft som håller fast planeterna i deras banor. Solen är egentligen en stjärna. Gravitation En av de viktigaste naturkrafterna i universum är gravitationen. Samma kraft håller kvar månarna runt planeterna. Man vet inte riktigt hur gravitationen uppstår. Eftersom månen är mindre än jorden är gravitationen mindre. Här kan du räkna ut hur mycket du väger på andra himlakroppar:www.ungafakta.se/stjarnorplaneter/? Astronauter Hur är livet som astronaut? För att kunna bli astronaut måste man ha nästan perfekt hälsa. Det är viktigt att astronauterna bygger upp sina muskler. Hur funkar det i rymden? Väl uppe i rymden är allting tyngdlöst. De enklaste vardagssysslor blir svåra i rymden.
Stephen Hawking: "Time Travel to the Future is Possible" Needed for assembly: "One wormhole, the Large Hadron Collider, or a rocket that goes really, really fast." Stephen Hawking thinks for of the world's physicists are wrong believing that time travel is impossible: Hawking sides with Sir Arthur Clarke, author of Space Odyssey 2001 who famously stated that "when a distinguished scientist states that something is impossible, he is very probably wrong". And a lot of distinguished scientists believe that just "Time travel is absolutely impossible". Hawking says: "Although I cannot move and I have to speak through a computer, in my mind I am free. Several of the planet's leading scientists, including Charles Liu (author of "One Universe: At Home In The Cosmos"), Brian Greene (of "The Elegant Universe") and Michio Kaku ("Hyperspace") float a raft of objections to the concept of time travel. Professor Greene states that all time-travel theories operate at the very boundaries of known physics, and are therefore unlikely to work. Links:
The Hole Argument 1. Modern Spacetime Theories: A Beginner's Guide Virtually all modern spacetime theories are now built in the same way. The theory posits a manifold of events and then assigns further structures to those events to represent the content of spacetime. This one example illustrates the core content of the hole argument. Here are the two, basic building blocks of modern, relativistic cosmology: a manifold of events and the fields defined on it. Manifold of Events. So far, all we have defined is a set of events. Figure 1. Metrical Structure and Matter Fields. These additional properties are introduced by specifying the metric field. Figure 2. That information could be supplied by a huge catalog that specifies the spatial or temporal distance between every pair of events along every curve connecting them. The matter of the universe is represented by matter fields. Figure 3. 2. The exercising of this freedom is the essential manipulation of the hole argument. Figure 4. Figure 5. 3. 4. 5. 6. 7.
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