Dekan

Thanks Insane_Alien for your reply. You've cut the length of time down to a million years and a bit. Even that seems incredibly long. I thought someone would prove it was something slightly more plausible. Like 10 years, or 100 years at the outside. But that's Modern Physics. It requires the willing suspension of disbelief. Thanks again, Dekan

Today I was reading a book, in which this passage occurs: "Air is made up of molecules, which are themselves made up of groups of atoms. A molecule is almost unbelievably small....to give an example: Take a small box with a capacity of 1 cubic inch, and fill it with ordinary air. If we release 10 million molecules every second, how long will it take for the box to empty itself completely? A second - a minute - a month? No - 50 million years!" This answer - 50 million years - strikes me as not credible. But I don't know how to do the maths to check it! Can anyone do the maths, and prove or disprove it please? Thanks, Dekan

Thanks pwagen for your very interesting post#2 - your point about Saturn not being just a dot, is what I was getting at. Although it looks like a featureless dot to our unaided eye, it's actually a planet with a lot of surface features. And rings. But we can't see these features from Earth - unless we use the method of either: 1. Leaving the Earth and traveling to Saturn; or: 2. Staying on Earth and looking through a telescope. Method 1 requires a lot of energy, but method 2 doesn't seem to. Even though it accomplishes the same result. That's what puzzled me. Re your mention of the old discredited theory of light-beams emitted from people's eyes: I suppose if we weren't humans, but intelligent bats, used to perceiving the world through our sonar-emissions, this theory would seem just plain common-sense! Thanks again for your reply. Dekan Thanks Swansont for your reply. I've read through the wikipedia article you kindly cited. While I don't pretend to understand all the maths involved, it's amazing what can be done with light-beams! But don't all these techniques, optical tweezers and so on, necessitate forceably pumping a lot of light in, so to speak? If a lot of energy is being pumped into something, then I can understand that it produces results. The thing about the telescope though, is that it seems to produce results without any energy being "pumped" or "forced" into it. The telescope just passively takes in the ambient light-energy. Yet it produces results - eg, showing Saturn's rings, which you couldn't otherwise see. That's what seems slightly spooky to me. Appreciate your reply, Dekan Thanks md65536 for your reply. I've watched the youtube video link you kindly supplied. This makes very clear that magnification is not the same as being closer - if you're only concerned with perspective and the relative position, or displacement of different objects. Magnification by optical means, ie Zoom, doesn't alter the apparent relative position of objects. Whereas physically tracking-in, does. I accept that. But in the case I'm thinking about, which is the amount of perceived detail on a distant object, such as Saturn, I don't think relative position or perspective are very important. In the video, I could perceive the same amount of attractive detail on Shelley's face, whether her face was zoomed or tracked-in. And presumably the same would apply in the case of Saturn's face. However I think the last part of your post has really answered my question. The extra energy which allows more details on a distant object to be perceived through a telescope, comes from the extra energy-collecting area of the telescope object-glass (or mirror). Seems obvious now! (Though what telescopes do still seems a bit magical) Thanks again for your reply - much appreciated. Dekan

Suppose you look at the planet Saturn in the night-sky, with your naked eye. All your eye shows you, is a point of light. This point of light, reveals nothing of Saturn's disc, the spots and cloud-belts on the disc, or the rings encircling the disc. These features can't be discerned, because Saturn is so far from the Earth. Say around 800 million miles away. If you wanted to see these features, you could get on a rocketship, take off from Earth, and journey to within say, 8 million miles of Saturn. Then you'd get a view of the disc, belts and rings. Since you'd be 100X closer. But getting this closer view, would require a lot of energy. In the form of fuel expended to take off from Earth. The fuel might be burning chemicals, nuclear fission, nuclear fusion, anti-matter reactions, or whatever. However, if you stay on Earth, and just look at Saturn through a telescope with a magnification of 100X, you get the closer view instantly, and apparently without any expenditure of energy at all. The telescope doesn't seem to expend any energy, or do any "work", in the Physics sense of the word. The telescope (in its simplest form) is just two pieces of unmoving glass: the object glass and the eyepiece. Which just passively transmit light. This strikes my naive brain as hard to understand: that two motionless lumps of glass can produce the effect of an "instant journey" to Saturn. Without any "work" being done. I'll be very grateful for any comments, help or guidance on this. Thanks.