

luc
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Posts posted by luc
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I'm asking: does life exist on other planet/s?. My thought is that life exist on other planet/s, and intelligent, the Universe is too great to have us as unique living beings
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The?
in The Lounge
Would you prefer me to use incorrect English? This language is flawed and a crazy concoction of meaningless phrases!I have no use for the. If teh was to be stricken from the world i would be a happy man. However' date=' if it pleases you, i shall never use it again.[/quote']
I second that. I won't use the word The anymore
Down with the word The!!!!
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There are a large number of four vectors in SR. You list some of them' date='
but also some that are not four vectors.
1. The velocity four-vector is (g,g v), where g is the SR gamma and v is the usual three-vector velocity we would measure as dx/dt.
2. Acceleration is not a four vector in SR.
3. Force (and acceleration) are not useful variables in SR.
A four-vector force, the so called "Minkowski force" can be defined by
F=(g dW/dt,g dp/dt} where W is the energy and p the three-vector momentum of a particle.
4. The energy-momentum four-vector is (W,p).
5. The displacement four-vector is (t,x,y,z).
6. The four-potential is usually written as (phi,A), where phi was the NR scalar potential and A the NR vector potential. A is no longer referred to as "magnetic" because it also affects the electric field.
7. The current four-vector is (rho,j).
8. There is a four-divergence, which is a four-vector.
9. Taking the four-divergence of tensors lead to other four-vectors.
10. ... and so on.[/quote']
Do you mean that there're an infinite number of different kind of 4-vectors? Or a finite number? If is a finite number what number is it?
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I mean the 4-potential where the components are (@,Bx,By,Bz), where @ is the scalar magnetic potential, and the Bs are the components of the vector magnetic potential
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Ok, i'm trying to figure out how many different 4-vectors exist in SR
-4-velocity
-4-acceleration
-4-force
-energy-momentum 4-vector
-displacement 4-vector
-4-potential
Is there some other? How many different 4-vectors exist in Special Relativity?
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aNYBODY?
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Tom, I'm referring to the Lorentz tensor used to transform a displacement 4-vector from one frame of reference to another
The equation goes this way:
D=LD'
where L is the Lorentz tensor
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Which are the components of the Lorentz tensor in SR if the signature of the Minkowski metric is (-+++)? Can you give me a link to some page showing them? Thanks
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If time slows down as object or person nears the speed of light, then wouldn't everyone in this universe be in different time (my soul is in different time than your soul. I've seen part of you that you haven't experienced yet) since everyone is moving in different speed?
You should try to define what's soul. I've seen gedankenexperiments in SR in which clocks are compared, but this is the first time that I read somebody wanting to compare souls
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How many stress-enrgy tensors exist? i know that there's the stress energy tnesor for a perfect fluid, that is the tensor that is habitually used to represent our Universe. there's also a stress energy tensor for a void universe. But I would like to know how many there are, I'm thinking even about the possibility that there exist an infinite number of different stress-energy tensors
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Is this why physicists prefer the formulation of SR in which there's no relativisitic mass. The notion of rest mass makes easier the calculations
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If you want to study it seriously, try the recent "A first course in String Theory", The author is B.Zwiebach
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Consider the landscape of string theory, with its bazillion of different vacua, each vacua representing an universe. Is possible to travel to another vacua?
If our universe is one of these vacua, can we travel to another vacuum? Is possible? Using a Black hole? Ideas, please
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I actually have 450 hours of SETI search in my computer, so if somebody discovers an alien I want a portion of it, a nail at least
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Nice that you brought it, so I have learned about an effect unknown to me called "light echo"
http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/02/
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http://www.universetoday.com/am/publish/upper_limit_star_size.html?422005
The maximum mass that a star can possess is around 120-200 solar masses
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I really would like to contact in my lifetime with one of those aliens. It certainly must be a mind opening experience. I hope that they will be pacifists and we don't have to wage a war against them
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is it the same one as my avatar?
Yes, it's the same. In september 2004 there appeared info about this planet, but then it was less sure that it was truly a planet.
Anyway (even that is impossible that this message get to them), greetings to the habitants of that distant planet! Here in Earth we are a bit crazy and bad tempered sometimes, but deep in our hearts we are good people!
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http://www.newscientist.com/article.ns?id=dn6864
"Astronomers have directly observed an extrasolar planet for the first time, but are at a loss to explain what they see."
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how can light travel faster than THE SPEED OF LIGHT IN A VACUUM? it just doesn't make any sense
http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html
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I read here and there that massless vector bosons carrying forces (e.g., the photon carrying electromagnetic force, or (if exist) the graviton carrying gravity force) can travel faster than light. I have never read tho' if there's a limit for that velocity, so I'm interested to know that limit, what's the maximum velocity that can acquire virtual particles
Bye
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Strings loose their energy to the expansion
How do you know this?
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I have a question about LQC. Is there inflaton (a scalar field) in this theory?
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Climatology, Tsunamis, and You...
in Ecology and the Environment
Posted
It seems something terrific, I wonder what measures can be taken against it. There's some way to stop such a mega-tsunami in its way towards the coast of the USA?. Is there any way to impede the collapse of the cliff in the Canary Islands?
http://www.bbc.co.uk/science/horizon/2000/mega_tsunami.shtml
"Although the volcano presents no danger while it is quiescent, scientists believe the western flank will give way completely during some future eruption on the summit of the volcano. In other words, any time in the next few thousand years a huge section of southern La Palma, weighing 500 thousand million tonnes, will fall into the Atlantic ocean.
What will happen when the volcano on La Palma collapses? Scientists predict that it will generate a wave that will be almost inconceivably destructive, far bigger than anything ever witnessed in modern times. It will surge across the entire Atlantic in a matter of hours, engulfing the whole US east coast, sweeping away everything in its path up to 20km inland. Boston would be hit first, followed by New York, then all the way down the coast to Miami and the Caribbean."