A few questions about astronomy/astrophysics.
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I'm only dabbling (not an astronomer)... The speed of light is constant; what happens in your example is there will be a violet-shift (only the frequency increases, not the velocity). Regarding mass and energy: they are interconvertible; energy has no mass but it can be transformed to some stuff with mass, the same way as mass turning to energy (E = mc2). I guess a black hole will be relatively hot (accounting for all those violent processes happening within). I hope others will answer, I also would like to know...
1) There is no such thing as an absolute reference frame. I'm trying to find the best words to describe this, but it's late and words fail me, so I'll just link you to Wikipedia.
http://en.wikipedia.org/wiki/Relative_velocity#Special_Relativity
2) Energy and mass are the same thing (or, more correctly, a mass has an associated energy and vice versa). Classical mass is what's called rest mass in relativity. Photons have energy but a rest mass of 0.
http://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence
3) Nobody knows. But:
http://en.wikipedia.org/wiki/Hawking_radiation
Which would also explain number 5 if anyone had ever observed micro black holes in particle accelerators. If they have, I'd certainly like to see an article.
Nilesh wrote:
Astronomy is really the only science that I've always loved (since I was a toddler). I recently watched "The Elegant Universe" and it sparked some questions.
1.) Why doesn't light follow the absolute reference frame rules that apply to other objects (like if you headed opposite a light beam it's apparent speed wouln't be the speed of light + your speed)?
2.) According to String Theory, everything is made up of strings... so If energy has no mass than how come the universe and the stuff on it does?
3.) Would a black hole be very hot or very cold?
4.) How do you come up with 12 dimensions in string theory ( be gentle so a teenager can grasp it)?
5.) Why would mini-black holes created in particle accelerators instantly disintigrate?
I would really appreciate any help with these.
I haven't seen the movie, but I've read Greene's book.
1. Just read that wikipedia link above, it's too hard to put in words without sounding confusing. With waves there is a similar effect- the phase velocity may exceed the speed of light but the group velocity will not.
2. Don't worry about String Theory, it's currently too speculative. None of its predictions can yet be tested. With a new particle collider being created at CERN though, which will be done soon, this may change. As for mass and energy, I don't understand your question exactly. Can you rephrase it?
3. Depends on what you mean. Something falling into a black hole heats up to extreme temperatures before getting engulfed. Recently we were able to measure a 'burp' if you will from the black hole in the center of our galaxy due to the high energy radiation emitted from the event. As for the actual black hole itself? I don't think giving it a temperature would even make sense, but I'm not really sure. I also think they have infinite density, and giving a temperature to something with this wouldn't make sense to me. Temperature is a measure of the kinetic energy of the molecules of an object or a region of space.
4.Really complex mathematics. As of yet, it just comes out of the math and there's no other way to arrive at the number of dimensions through any sort of theory, which I think is what you're asking. So where are the other dimensions? Well, nobody's really sure yet. They could be curled up so tightly that we don't notice them, or it's possible that our 4 dimensional space is a pocket in a larger dimensional space, or a host of other theories.
5. These would only be about the size of an electron and I think they would probably evaporate quickly due to emission of Hawking radiation but I don't know
Soulcrates, in response to your first paragraph, this is what I believe the currently accepted phyical theory is:
No matter what speed you're travelling at, light will appear to be travelling at the speed of light. This means if you yourself are moving at the speed of light you'll still measure the light as moving at that speed too, 3 * 10^8 meters/second. Any particle with 0 mass, not just the photon, travels at the speed of light by necessity. As for faster-than-light travel, it takes an infinite amount of energy to accelerate something with mass up to the speed of light and anything with 0 mass automatically travels AT the speed of light, so there is nothing faster than light.
Nilesh wrote:
Astronomy is really the only science that I've always loved (since I was a toddler). I recently watched "The Elegant Universe" and it sparked some questions.
1.) Why doesn't light follow the absolute reference frame rules that apply to other objects (like if you headed opposite a light beam it's apparent speed wouln't be the speed of light + your speed)?
There is no absolute reference frame. This my be helpful from my blog (my real name is Akiko)
http://gnabgib.blogspot.com/2007/07/einstein-was-right.html
This may interest you also.
http://gnabgib.blogspot.com/2006/01/true-nature-of-force_13.html
2.) According to String Theory, everything is made up of strings... so If energy has no mass than how come the universe and the stuff on it does?
String theory is highly speculative and unproveable. It is like asking a circle why isn't it a sphere. There is no way for the circle to ever understand what a sphere is, let alone prove they exist. It has been speculated that the Big Bang may be a result of a gi-normous "glitch" that owes itself to the Heisenberg uncertainty principle. In other words, energy from nothing.
3.) Would a black hole be very hot or very cold?
Black holes have a temperature according to the Hawking Radiation (this is due to the Heisensenberg Uncertainty Principle). If a body radiates, it has a temperature, albeit very near absolute zero. Moreover, black holes have specific entropy, numerically equal to the surface area.
http://gnabgib.blogspot.com/2007/08/black-holes.html
4.) How do you come up with 12 dimensions in string theory ( be gentle so a teenager can grasp it)?
The 12 dimensions come about from the math, in much the same way if you solve a quadratic equation, you get 2 answers, not one. In this case, 12 dimensions are needed to make sense of the math.
5.) Why would mini-black holes created in particle accelerators instantly disintigrate?
Partical accelerators do not produce mini black holes because they are not powerful enough (not even the LHC) . The only place where they could possibly have come from is the big bang. Incidentally, as all black holes give off Hawking radiation, they all in principle would "evaporate"! Before that happens, however, they would explode when certain parameters exceeded certain values.
I would really appreciate any help with these.
I hope this will help you. All the links are to my blog www.gnabgib.blogspot.com
Jan 14, 2008
0
#7
if you can believe in string theory, quantum physics, quantum electrodynamics and superpositioning, then there's absolutely no reason why you can't believe in God.
Soulcrates wrote:
2.) It's a theory, as much as I can understand from it, I assume that the mass is so minute that they assume it is 0, like sunlight.
3.) Would a black hole be very hot or very cold?
I would assume very hot.
2. Sunlight does have mass. It can be proved quite easily.
3. I would assume near absolute zero since it cant radiate heat. But thats probably too assumptive!
Why does someone always want to bring god into these discussions, unbelievable.
If you want to discuss god then go here. It is a new add-on to chess.com where you can discuss sensitive issues like god, politics etc.
http://www.chess.com/groups/home/open-discussion
Red
I'm fascinated by such scientific knowledge, and hopefully someday such knowledge will be further unraveled.
With due respects I think e-check's point is that those theories are so hard to comprehend (string theory, quantum physics, quantum electrodynamics and superpositioning) that the absolutely simple concept of God is very appealing. Many serious scientists believe in God--not solely due to science--because science cannot directly prove or disprove his existense, I guess in this point Redserpent2000 is right in my opinion. With all that said, I think I have to follow the rule of 'no religion/politics' here.
Charlie91 wrote:
I'm fascinated by such scientific knowledge, and hopefully someday such knowledge will be further unraveled.
With due respects I think e-check's point is that those theories are so hard to comprehend (string theory, quantum physics, quantum electrodynamics and superpositioning) that the absolutely simple concept of God is very appealing. Many serious scientists believe in God--not solely due to science--because science cannot directly prove or disprove his existense, I guess in this point Redserpent2000 is right in my opinion. With all that said, I think I have to follow the rule of 'no religion/politics' here.
I guess you should all read this, then.....
http://gnabgib.blogspot.com/2007/02/holmes-i-have-sore-neck.html
Nilesh wrote:
Astronomy is really the only science that I've always loved (since I was a toddler). I recently watched "The Elegant Universe" and it sparked some questions.
1.) Why doesn't light follow the absolute reference frame rules that apply to other objects (like if you headed opposite a light beam it's apparent speed wouln't be the speed of light + your speed)?
2.) According to String Theory, everything is made up of strings... so If energy has no mass than how come the universe and the stuff on it does?
3.) Would a black hole be very hot or very cold?
4.) How do you come up with 12 dimensions in string theory ( be gentle so a teenager can grasp it)?
5.) Why would mini-black holes created in particle accelerators instantly disintigrate?
I would really appreciate any help with these.
I'm a teacher of Physics K6-12, and Astronomy..
I may tell you that.. black holes absorbe the electromagnetic waves and particles around its till a critical radius (R0) ..
The temperature definition may come throught energy of particles or waves .. but, seems no one of them comes out from this object .. we may say that, this object is out of the temperature deffinition, it has no temperature ..
Nilesh wrote:
3.) Would a black hole be very hot or very cold?
Hard to answer on this question... Cold or hot is just human's feeling - if you will be at black hole you won't have any feelings - you would be dead. But being cold means absorbing energy from envinronment, what is warmer. Being hot means giving energy to envinroment, what is colder. Then I guess black hole might be considered cold(just my opinion).
It's confusing when you try to visualise quantum physics in terms of Newtonian mechanics. Assumptions which everyone makes regarding relative speed etc just simply do not apply.
Did you know that it has already been proved that objects travelling at very high speeds 'go slower'. (This was done using atomic clocks).
The problem is that we talk of distance and speed which is equivalant to talking about space and time. But space and time are inextricably linked. We should talk in terms of the space-time continuum.
Just to throw us into further confusion, the 'impossible' has apparently been achieved by accelerating a (very small) particle to faster than the speed of light (!!!!) (for an incredibly short time).
Trying to get your head round this is like trying to explain to an ant in London what the Sydney harbour bridge is like. What is infinity....? Where did all this matter come from...? Does the Universe expand,contract or just hang at the end of time...? What is the end of time if time is infinite...?
What we do know now is at the very edge of human knowledge and therefore very difficult to comprehend.
Stuff like sunlight exerting pressure because it has mass is actually pretty standard easy physics. If you cant get that, you have got no chance with quantum physics.
mxdplay4: "Stuff like sunlight exerting pressure because it has mass is actually pretty standard easy physics."
Even massless particles like photons can carry momentum.
Loomis wrote:
mxdplay4: "Stuff like sunlight exerting pressure because it has mass is actually pretty standard easy physics."
Even massless particles like photons can carry momentum.
Photons have relativistic mass due to their velocity, but no inherent mass like we are used to in everyday situations (resting mass). I'm not disagreeing with Loomis since his statement is correct in the major sense. But it just shows that this is a very difficult area to get your head around.
yeah, the photons or 'sunlight' dont have mass, simply momentum.
This particle you describe... how did they measure the speed?
"Just to throw us into further confusion, the 'impossible' has apparently been achieved by accelerating a (very small) particle to faster than the speed of light (!!!!) (for an incredibly short time). "
Somehow I don't think that's true. The only FTL things I've heard of have to do with the phase velocity of an EM wave. If something with any rest mass whatsoever was accelerated even up to the speed of light (let alone exceeding it), it would be a very very big deal, regardless of how little time that particle spent at that speed.
I've heard something about photons being sent FTL using quantum tunneling, but I'm not sure I believe this and I've also heard that it still provides no way to transmit information FTL.
The temperature definition may come throught energy of particles or waves .. but, seems no one of them comes out from this object .. we may say that, this object is out of the temperature deffinition, it has no temperature ..
"No-one of them comes out of this object" True, but Hawking radiation makes it SEEM that way.
Kingskiller wrote: Nilesh wrote:
3.) Would a black hole be very hot or very cold?
Hard to answer on this question... Cold or hot is just human's feeling - if you will be at black hole you won't have any feelings - you would be dead. But being cold means absorbing energy from envinronment, what is warmer. Being hot means giving energy to envinroment, what is colder. Then I guess black hole might be considered cold(just my opinion).
Cold or hot is a human's feeling, but there is a definition ot if. Surprisingly, it is called "temperature". This can be measured according to standards agreed upon many years ago. "Cold" being a lower temperature than that humans are used to, "hot" being the opposite.
A black hole is thus cold, "radiating" particles of Hawking radiation at a much less rate than that humans are used to.
Astronomy is really the only science that I've always loved (since I was a toddler). I recently watched "The Elegant Universe" and it sparked some questions.
1.) Why doesn't light follow the absolute reference frame rules that apply to other objects (like if you headed opposite a light beam it's apparent speed wouln't be the speed of light + your speed)?
2.) According to String Theory, everything is made up of strings... so If energy has no mass than how come the universe and the stuff on it does?
3.) Would a black hole be very hot or very cold?
4.) How do you come up with 12 dimensions in string theory ( be gentle so a teenager can grasp it)?
5.) Why would mini-black holes created in particle accelerators instantly disintigrate?
I would really appreciate any help with these.