StringJunky

I agree with Moon, seven is too early. I think it wants to be just before high school or at the start when matters of sex and relationships are most likely starting to enter their awareness naturally. I'm all for allowing naivete to prevail as long as practically possible; one is an adult a lot longer than one is a child.

That's what was puzzling me: the further away something is the the more the perspective compresses and so should appear to move slower with increasing distance. I need to get down to first principles on this subject which I lack.

Imatfaal's demo was fine for me...I was only interested in the increasing rate-of-recession velocity aspect which he clearly demonstrated his suggestion that it is an artifact of expansion; it didn't matter about the marks expanding as that was irrelevant in this instance. You might take some time out studying what analogies are and their limitations and also you can't expect someone to give a whole treatise covering every aspect of cosmological expansion in one post...that's what books are for.

Thanks for putting that together imatfaal. I appreciate it. I replicated your demo to help me see what was happening and I think I see what you mean. I took on board what Airbrush said and done this graphic...is it correct?

The further away a receding galaxy is from us the faster it recedes. Is the increasing rate of recession with distance due to spacetime curvature; much like, analogously, when you see the sun setting...it apparently 'drops' quicker towards the horizon? I can't get my head around why the recession velocity increases with distance. I have no problem understanding expansion itself from any given point.

The longest wavelength is twice the length of a string not the same as. Strings: Each end of the string is fixed and therefore a node with an antinode in the middle. Since the wavelength is twice the distance between the nodes, the longest wavelength is twice the length of the string. This is known as the fundamental mode or fundamental frequency. http://ibphysicsstuff.wikidot.com/standing-waves

What does that mean?

ajb, a person is gay or not, one can't encourage it. The law in the UK allows for the freedom of expression of ones gender preference and if that represents normalisation then more power to that law. I think it is important that it is put across to the youngsters that same-sex attraction is normal; what's the point of having law declaring equal rights if the establishment doesn't visibly act as though they are equal? We are still in the learning curve, as a society, trying to bring this aspect of human relationships to point where it's a non-issue and that's why it's brought to light in the classroom. At the most, regarding your concern, some essentially heterosexual youngsters may try it in the spirit of experimentation but ultimately their own biology will kick in and they will pursue heterosexual relationships...no big deal. I've read enough to know that being surrounded by gay people or gay information does not make a person gay. You don't like onions, say; is being surrounded by them and understanding their life cycle going to make you want to eat them? You won't concern yourself about anyone else eating them will you? It's not my cup of tea but for some people it is and I really don't think they should have any status in society less than mine. As a society in Europe we are in transition, slowly embracing behaviours that were once not acceptable and the education system is bringing that to reality. The system is only encouraging those with gay aspirations to feel normal...it is only bringing those, like who once stood in the shadows, into the light.

This section is not the place for beliefs.

What about the separation from centrifugal forces in a spinning, molten early-Earth? The heavy radioactive elements would be on the outside wouldn't they? I read this in a hypothesis for the formation of the Moon where there was a sufficient concentration to cause an eruption that lead to a separation of a portion of the Earth's material into space. Nasa article: http://lunarscience.nasa.gov/articles/did-the-moon-form-in-natural-nuclear-explosion/ The paper: http://arxiv.org/abs/1001.4243 This is not actual evidence against what you saying but it is a proposed possible mechanism.

If you get Stardust by John Gribbin it will give you a gentle, very readable introduction to chemistry and how all the elements came into being in the cosmos making up everything around us including ourselves. It should help give you a sound start for your sci-fi stories giving them a little bit of scientific plausibility where you can give it!

Chemical elements are defined by the number of protons in their nucleus; each additional proton creates a new element. The first 98 elements occur naturally. The ones that contain 92 protons or more, become more and more unstable with each additional proton such that eventually they can only be synthesised in the lab and exist for only a very brief time before they lose some of their nuclei components and become one of the more stable elements with fewer protons. The upshot is that the chances of finding a new stable element are about zero so the chances of life forming, based on an undiscovered element, are the same.

Science is not deliberately obfuscated; when one starts to talk about fundamental mechanisms and phenomena in the verbal or visual form we have to use abstractions and analogies that use real world examples that are, in reality, only coarse approximations of what's really happening. The only way to really get to grips with it is via the use of maths. If you can't do that you are going to have a tough time understanding it properly. Most scientific concepts are mathematical constructs derived from measurement...it's quite removed from everyday methods of analysing things and this is probably why you find it so alien. Just keep reading science by scientists and you'll eventually get used to it. You could ask here for layman's treatments of any ideas that you are interested in. John Gribbin's books for cosmological subjects are quite accessible for example.

He's trying to make the world fit his beliefs rather than the other way round...like all good creationists.

That's why chemical reactions "don't happen from miles away".

Probability decreases with distance.

Quoting DH: A rest frame of some object is a reference frame in which the object's velocity is zero. One of the key axioms of special relativity is that light moves at c in all reference frames. The rest frame of a photon would require the photon to be at rest (velocity=0) and moving at c (velocity=299792458 m/s). That of course is contradictory. In other words, the concept doesn't make sense. Forget about looking at things from the frame of a photon.

In science, this is how it's decided and all that matters here...I can't think of a better way of looking for "Truth":

The human eye is crap as an objective measurement tool because it automatically adapts colour balance and light intensity to some preset 'optimum', for example: the eye/brain interface will change the colour balance of an off-white lit white object so that you see a more balanced white with respect to red/blue bias...within limits.

We can't talk about reality in analogue because that is one continuum and in order to communicate about it we must 'digitise' the world (attach labels to arbitrarily defined boundaries) in order to share our experiences which, as a consequence, adds complexity to its description.

How can the universe expand if space is not expanding and preserve isotropy and homogeneity (or don't you think so?)? Your apparent alternative implication is an expanding 'island universe' in a sea of pre-existing space. Also, if redshifting galaxies are accepted, they can't physically move at superluminal speeds (Re: SR), so, space expansion is the only other option or do you assert physical objects can move FTL into a pre-existing space?

It looks like John Cuthber's watching your back. Keep learning mate...I know you are not knowingly irresponsible. For future reference, it might be better to word a practical idea that you are not familiar with, like you just did, in a hypothetical sense so that it might be corrected ie "What if we...?", then you should be covered against any sharp criticism.

Are you hitting the 'back' button on your browser after submitting?...this does it.

I agree. Regular posters here, particularly n Chem, really should think twice before making practical suggestions...some passing reader may just try it with life-harming consequences.

Bad: When the astronauts are assembling the American flag, the flag waves. Kaysing says this must have been from an errant breeze on the set. A flag wouldn't wave in a vacuum. Good: Of course a flag can wave in a vacuum. In the shot of the astronaut and the flag, the astronaut is rotating the pole on which the flag is mounted, trying to get it to stay up. The flag is mounted on one side on the pole, and along the top by another pole that sticks out to the side. In a vacuum or not, when you whip around the vertical pole, the flag will ``wave'', since it is attached at the top. The top will move first, then the cloth will follow along in a wave that moves down. This isn't air that is moving the flag, it's the cloth itself. New stuff added March 1, 2001: Many HBs show a picture of an astronaut standing to one side of the flag, which still has a ripple in it (for example, see this famous image). The astronaut is not touching the flag, so how can it wave? The answer is, it isn't waving. It looks like that because of the way the flag was deployed. The flag hangs from a horizontal rod which telescopes out from the vertical one. In Apollo 11, they couldn't get the rod to extend completely, so the flag didn't get stretched fully. It has a ripple in it, like a curtain that is not fully closed. In later flights, the astronauts didn't fully deploy it on purpose because they liked the way it looked. In other words, the flag looks like it is waving because the astronauts wanted it to look that way. Ironically, they did their job too well. It appears to have fooled a lot of people into thinking it waved. This explanation comes from NASA's wonderful spaceflight web page. For those of you who are conspiracy minded, of course, this doesn't help because it comes from a NASA site. But it does explain why the flag looks as it does, and you will be hard pressed to find a video of the flag waving. And if it was a mistake caused by a breeze on the set where they faked this whole thing, don't you think the director would have tried for a second take? With all the money going to the hoax, they could afford the film! Note added March 28, 2001: One more thing. Several readers have pointed out that if the flag is blowing in a breeze, why don't we see dust blowing around too? Somehow, the HBs' argument gets weaker the more you think about it. http://www.badastronomy.com/bad/tv/foxapollo.html#flag'>http://www.badastronomy.com/bad/tv/foxapollo.html#flag If you want any other questions about the landing addressing: http://www.badastronomy.com/bad/tv/foxapollo.html