101

Physics, Astronomy & Cosmology / Re: Is spacetime real?

« on: 26/09/2016 20:16:36 »

Having drifted into talking about particle spin, this might be worth looking at.  I’m not always happy with the answers here, but this seems not bad.

http://www.askamathematician.com/2011/10/q-what-is-spin-in-particle-physics-why-is-it-different-from-just-ordinary-rotation/

102

Physics, Astronomy & Cosmology / Re: Can gravity really interact with itself?

« on: 13/03/2016 20:22:29 »

I have seen it stated that since the gravitational field has energy it can produce gravity just like mass does. Is this necessarily true?

My understanding is that GR says that gravity creates gravity.  I've been looking for where I got this idea and can't find at the moment.  It has come up in discussion on other forums, and seems to be accepted widely.

An interesting point that arises from it must be: Why do we not observe run-away gravity?  Why doesn't every massive body spontaneously collapse into a black hole?

103

Physics, Astronomy & Cosmology / Re: Are these the 8 reasons why people from the future have not come back in time ?

« on: 03/01/2016 17:14:41 »

1. They never did it, they could not even do it with a googolplex years from now, with the amount of human progress in technology.

Considering the rate at which technology progresses, that may be a rash prediction.  My own feeling is that something more fundamental than technology will prevent past directed time travel.
 
2. They have done it but they put some kind of causality lock on the time period they come from, keeping them safe from causality changes through time.

Even J Richard Gott, who argues for the possibility of past directed time travel, points out the difficulty and expense.  Would it not seem pointless to go to that trouble and do nothing with the results?

3. They create another dimension to go to the past in, exactly like our own in every way, so there is no causality effects on them.

That’s a lot more complicated than it sounds.  There have been many attempts to use the multiverse idea to achieve PDTT, some of them seem to work, but, I suspect, only because they are not thought through completely.

4. They can just view the past but not interact with it, as they travel through time backwards, or even view it on a television monitor.

Is that really TT, or just retro-viewing?

5. They have achieved time travel but are not interested in visiting our time period.

I’ll pass on that one, as we have no way of knowing, unless they change their minds. []

6. they can only go back in time short term like a few seconds, and they cannot go back in time before the time machine was built, or before they were born.

Going back just a few seconds would lead to all the problems of “full scale” PDTT.  Some of those might be averted if it were not possible to go back beyond the invention of the machine, but it would be only temporary.

7.They can only send information back in time, and again short term or there is going to be causality problems.

Who would receive the information?

8. Even short term maybe they cannot send people, or information back because they instantly get thrust somewhere else, or either killed, or even create a infinite paradox loop that they can never escape.

Lots of problems here. The biggest, I think, is the inescapable loop.

3, 6 and 8, especially, need more comment/explanation, but on the principle that the length of a post is inversely proportional to the number of people likely to read it, I will leave out those comments unless someone wants them.

104

Physics, Astronomy & Cosmology / Re: Does the sky have gates where the rockets pass through to space?

« on: 01/12/2015 18:19:51 »

Utter drivel.

Reminds me of a joke I heard on an Open University summer school.

A geologist takes a trip in his hot air balloon to photograph the Fens (an extensive area of flat country).  During the flight a fog rolled in from the North Sea.  The geologist descended very slowly and carefully.  Suddenly he became aware of the head of a cyclist just below his basket.  The following exchange took place:

Geologist:  “Excuse me”.

Cyclist (wobbling dangerously):  “Er, hello”.

Geologist: “Can you tell me where I am?”.

Cyclist: “Yes, you’re in a basket suspended below a hot-air balloon”

Geologist: “Thanks; you must be a physicist”.

Cyclist: “How did you know that?”

Geologist: “because your answer is absolutely right, but totally useless”, 

105

Physics, Astronomy & Cosmology / Re: Can we put an end to the nonsense of "duality"?

« on: 21/11/2015 19:56:28 »

How about: There is no duality, because the photon is neither a wave nor a particle; it appears to us as one or the other because of the different ways in which we observe/interpret it?

106

Physics, Astronomy & Cosmology / Re: Has there been only ONE Big Bang???

« on: 13/11/2015 22:09:52 »

Hi Jaye, welcome.  I have not read all of your OP yet, but one thing jumps out of it right at the start, probably because I had trouble with that sort of thing, and still get involved in convoluted discussions about "nothing" and "nowhere". []

  "Something can't be nowhere?", correct? In saying so much, for us to start as a speck of energy, that speck of energy would have to have a place to call home, a position in, for lack of a better word, reality. But wouldn't this just contradict the idea that EVERYTHING comes from the Big Bang....

You have almost answered your own question. "Something can't be nowhere?" Agreed; but it can be everywhere.  If the Universe is all there is, it is everywhere, and always has been; even when it was a minuscule speck.

107

Physics, Astronomy & Cosmology / Re: Higgs Bosen developments?

« on: 28/10/2015 23:29:46 »

This is not a bad place to start getting your head round the Higgs field/particle. The original articles may not be very up to date, but Matt will always answer questions.

http://profmattstrassler.com/articles-and-posts/the-higgs-particle/the-discovery-of-the-higgs/

http://profmattstrassler.com/articles-and-posts/the-higgs-particle/the-higgs-faq-2-0/

108

Physics, Astronomy & Cosmology / Re: Could you become a God by traveling at the speed of light?

« on: 26/10/2015 13:06:36 »

 Hi Mohammad, welcome to TNS.
 
Pete is right, of course, this should be in new theories, and much of the ensuing discussion is also misplaced.
 
I’m no expert, but I see a few problems with your reasoning, from the point of view of relativity in particular.
 
From a metaphysical perspective you make some interesting points.  Have you read Fred Alan Wolf’s “The Yoga of Time Travel”? if not give it a go, you might find it interesting.
 

109

Physics, Astronomy & Cosmology / Re: Why we spend money on space exploration when we have so many problems here ?

« on: 18/10/2015 14:32:34 »

Mscientist9, the “?” at the end of your OP may have been a bit misleading, and is no doubt responsible for the responses so far.

I suspect that by “we” you meant governments; if so, your question is a good one, and one to which the answer is very complex.  Personally, I doubt that the survival of humanity in the far future is high on the agenda of any government, but there are more short term considerations. 

Space exploration is just one of the range of scientific/technical areas from which improvements can come which benefit humanity.  Unfortunately, those who first feel the benefits are rarely those who need them most, but that’s a social problem, rather than a scientific one.

Money spent on space exploration is not literally thrown into space.  It provides work for thousands, and keeps large sums of money circulating, which is the essential basis of a healthy economy.  Again, it may be the less needy who benefit, but the solution to that is not likely to be stopping scientific progress.

The problems that really need to be addressed are things like distribution of wealth; persuading “big business” to pay their taxes; electing governments who actually care more about people at the lower end of the socio-economic scale than about making the rich richer.  Good luck with that; but that was not really your point, was it?

110

Physics, Astronomy & Cosmology / Re: The Moon orbits Earth, the Earth the Sun, Sun the Milky way...The Universe?

« on: 06/04/2012 17:59:20 »

Interesting that no one addressed the last part of the OP.   

  In an article in New Scientist, Marcus Chown (10.06.2006. Pp. 34-37) looks at the work of Pawel Mazur, George Chapline and others who think it is quite possible that the entire cosmos is “spinning on an axis”.   So their work might be a good place to start.