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AP Photo Black Hole Seen Ripping Star Apart
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Actually, your explanations are very good.
Originally posted by Mr. Anderson
That's a 2D representation. Rotate that curve around an axis diagonally through the center in the quadrants that don't contain the curve and you get a way to reach both sides (requires more dimensions, but there actually are so it might happen)
D
Actually, it's a 2D representation because it has to be. And, no, there aren't more dimensions. What's missing is the units on the graph. Also, the assymptote is not located around the origin, but around the speed of light. So, it takes an infinite amount of energy to accelerate from below the speed of light to the speed of light, or to decelerate from above the speed of light to the speed of light. So, in principle, if there were a way to skip over the speed on light, then it would be possible, from an energy stand point, to go faster than light. In fact, it would get easier to go faster.
However, I am glossing over one significant point. Inorder to be traveling faster than the speed of light an object needs to have an imaginary mass. What is imaginary mass? Well, we really don't know. The models that we have don't prohibit it, but we've yet to see anything that's made of imaginary mass. (Which makes sense, as something with imaginary mass would have to be traveling faster than the speed of light...)
Here's a better graph:
Attachments
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I'll be damned. Another PacificT.com Graphing Calculator connoisseur!
And I'm going with Doctor Q on this one: Keep lecturing.
Dudes, you guys know seemingly so much. Did all of you guys major in Physics or something?
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I'll be damned. Another PacificT.com Graphing Calculator connoisseur!
And I'm going with Doctor Q on this one: Keep lecturing.
Dudes, you guys know seemingly so much. Did all of you guys major in Physics or something?
Hmm, if you were traveling at or greater than the speed of light, and looked behind you. Would you see nothing? Or would it be a near still image? Hmm, that would be great for the Photography MMMMMMMMMCXI Thread
Originally posted by Counterfit
Hmm, if you were traveling at or greater than the speed of light, and looked behind you. Would you see nothing? Or would it be a near still image? Hmm, that would be great for the Photography MMMMMMMMMCXI Thread
I would say that if you were traveling AT the speed of light, and looked directly behind you, you would see nothing. Light has to coninuing hitting the eye for us to see an "image", and to do so the light must be moving toward your eye, which it could not do if you were at the speed of light. Now if you were within a FRACTION of the speed of light, you would probably see a near still image, because the change in light would be very very little.
King Cobra- I'm sure a few here are college grads that majored in something to do with this topic, but a number of us (myself included) know jack shiet, we just read this stuff for fun
Tyler
Earendil
Originally posted by King Cobra
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I'll be damned. Another PacificT.com Graphing Calculator connoisseur!
Yup. Great little app and it runs fine in Classic mode. I downloaded the other apps that were mentioned in the other thread. Some of them look promising...
Happy to. Of course having a specific topic to talk about helps. Most of the questions that were brought up earlier have been answered at this point. Also, it helps to have a good idea how much depth people would like me to get into.
Actually, yes.
Originally posted by Counterfit
Hmm, if you were traveling at or greater than the speed of light, and looked behind you. Would you see nothing? Or would it be a near still image? Hmm, that would be great for the Photography MMMMMMMMMCXI Thread
Actually, it doesn't make sense to talk about 'looking' when traveling faster than the speed of light. Theories of 'tachyons' are rather the blacksheep of the physics community. Most physicists won't touch such theories with a ten foot pole. In any event, if you were to talk about 'seeing' things from the perspective of a FTL being, then there would have to be a very high speed, low energy particle that would be used as a sensory organ. In other words, such beings wouldn't see with light. It would be like using sonar to navigate an airplane traveling at super-sonic speeds. It just wouldn't work.
Further, if you were traveling at the speed of light (which, as I've already discussed is impossible, but if it weren't...) time would be standing still due to the Lorentz space-time contraction. So, if time is standing still for you, can you 'look' in any direction?
Originally posted by Snowy_River
Actually, yes.
Well that makes sense. I'm planning to join you guys soon anyways. Astrophysics (PHY 281) is on my grad. list.
There is a roman symbol for 5000. It's a "V" with a line above it. Just like there's V for 5 million. I'm not sure what happens after that, though.
Originally posted by Counterfit
Well then, the Photography VVMVCMXCIX thread
That's 10,004,999 right?
I think that the proper representation would be:
-->_
XMVCMXCIX
Does that mean the following?
I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1,000
overbar V = 5,000
overbar X = 10,000
overbar L = 50,000
overbar C = 100,000
overbar D = 500,000
overbar M = 1,000,000
V = 5,000,000
X = 10,000,000
L = 50,000,000
C = 100,000,000
D = 500,000,000
M = 1,000,000,000
I'm sure it is very common for people to represent astronomical distances and times in Roman numerals
so we'd better get it right! Can you imagine Carl Sagan saying "There are Ms and Ms of stars..."?With the overbar and underbar convention, it's clear that we have one more letter symbol that we need. We could get rid of M and replace it with overbar I, i.e.,
I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
overbar I = 1,000
overbar V = 5,000
overbar X = 10,000
overbar L = 50,000
overbar C = 100,000
overbar D = 500,000
I = 1,000,000
V = 5,000,000
X = 10,000,000
L = 50,000,000
C = 100,000,000
D = 500,000,000
aw, but black sheep are all the rage right now. this explains special relativity very well, along with black holes and lorenz contraction.
my understanding is that bending of time is not caused by contraction, which is related but part of the bend itself. the cause is the presence of mass, and with it, gravity (or acceleration, which is ultimately indistinguishable from gravity).
see the "light clock" example in the book linked above for an explanation of the link between velocity and experienced time.
my understanding is that bending of time is not caused by contraction, which is related but part of the bend itself. the cause is the presence of mass, and with it, gravity (or acceleration, which is ultimately indistinguishable from gravity).
see the "light clock" example in the book linked above for an explanation of the link between velocity and experienced time.
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Snowy_River, thanks so much for your explanations! It's really interesting to read discussions like these...
But I'm wondering about one thing: If time is standing still when travelling at light speed, then even with infinite energy this boundary couldn't be crossed: you'd just stop there. Unless someone figures out how to "jump" into faster-than-light speed. But that's science fiction...
If one day we could travel faster than light, would people try to sell you diets to shed your imaginary pounds?
But I'm wondering about one thing: If time is standing still when travelling at light speed, then even with infinite energy this boundary couldn't be crossed: you'd just stop there. Unless someone figures out how to "jump" into faster-than-light speed. But that's science fiction...
If one day we could travel faster than light, would people try to sell you diets to shed your imaginary pounds?
Here's a quick tutorial about special relativity. There's even a nice animation there to help explain the light clock.
First, I'm not fond of talking about 'bending' time. Time, like space, is subject to the Lorentz effect. Whereas space undergoes a contraction (gets smaller) along the direction of travel, time dilates. This effect is present when comparing any two inertial reference frames that are moving at different velocities.
Now, it is true that this could be seen as introducing a contradiction. If we are moving relative to each other, then I'd say that your clock is running slow and you'd say that my clock is running slow. So where does acceleration (i.e. gravity) come into play? Well, it is when I accelerate to be moving at the same speed as you are so we can compare our clocks that my time get truly messed up. It is in the process of accelerating that true time dilation happens.
However, time dilation due to gravity can be explained using the geometric space model for what the effect of gravity is. In a gravitational field, space is contracted, so a 1 m length fits into what appears to be .5 m (for example, though that would be quite a bit of gravity). So, it would take longer for a beam of light to travel the apparent .5 m, because to the beam of light it would be 1 m.
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You're welcome. It's a lot of fun for me, too.
Well, it doesn't really make sense to talk about 'infinite' energy, anyway. You'd be talking about using more energy than has ever existed. More energy than was contained in the Big Bang, and, by extension, more energy than is contained in the entire universe.
Hmm...
I wonder if I should start a physics discussion thread, kind of like the photography threads. I could choose a new topic every week or two and give a quick, impromptu lecture on the topic. If anyone was interested in such a thing...
I would "attend" your lectures. And I can't wait to use the excuse "a black hole ate my homework" when I'm late with my assignments.
have at it
It'd be great to discuss physics - we do pretty regularly as it is. It just takes someone willing to organize it.
D
That is much better, and my point is less on the imaginary mass issue and more of 'alternatives' to the speed of light. Its pretty much scifi, but there has been some real work done concerning wormholes and other methods of circumventing the limits. There are so many other issues to worry about traveling close or even partial velocities of c - kinetic energy and moving through space (which isn't empty). What happens when you're traveling .5 c and you hit a grain of sand
D
Originally posted by Mr. Anderson
What happens when you're traveling .5 c and you hit a grain of sand
D
Well, give the rather famous equation for energy
Which, when the item in question has a relativistic velocity, is given as
Where gama is defined as
Thus, the kinetic energy of this grain of sand is
Now, to get an idea of just how hard this would hit us, let's assume that the grain of sand has a mass of 1 gram, and consider what the speed of an object with a mass of 1000 kilograms (a little over a ton, for those more used to english units) would have to be traveling at to have the same kinetic energy.
For our more massive object, we can assume that it's not traveling at relativistic speeds, so the Newtonian equation for kinetic energy would suffice:
Now, equating these, and taking advantage of the fact that M is simply one billion time m, we can solve for
So, that grain of sand would be the equivalent of being hit by a one ton car traveling at 5 km/s (which is about 11600 miles per hour).
Today's Los Angeles Times has a cover story about the long-delayed Gravity Probe B project being planned at Stanford University. And I do mean long-delayed. This experiment, intended to validate or disprove the general theory of relativity, was invented in 1959 and has been canceled or delayed by NASA repeatedly. After years of research and preparation, the first launch was scheduled for 1975 and then canceled. It has been put off 7 times since then.
Meanwhile, the technology behind the experiment has continued to improve. A spinning (10,000 rpm) gyroscope is put in a polar orbit in order to measure the warping of space-time and the "frame dragging" effect. The sphere, made from superpolished quartz, is the size of a ping-pong ball. It is suspended by electromagnets and spun by puffs of helium gas in a near-vacuum at near-zero temperature.
I love these facts: If the ball was the size of the earth, the tallest mountain would be 8 feet tall. Its ability to detect tilt would be the equivalent of discerning Lincoln's forehead on a penny from 3,600 miles away.
The mission is rescheduled for this April and will take 18 months to produce the results it seeks.
Meanwhile, the technology behind the experiment has continued to improve. A spinning (10,000 rpm) gyroscope is put in a polar orbit in order to measure the warping of space-time and the "frame dragging" effect. The sphere, made from superpolished quartz, is the size of a ping-pong ball. It is suspended by electromagnets and spun by puffs of helium gas in a near-vacuum at near-zero temperature.
I love these facts: If the ball was the size of the earth, the tallest mountain would be 8 feet tall. Its ability to detect tilt would be the equivalent of discerning Lincoln's forehead on a penny from 3,600 miles away.
The mission is rescheduled for this April and will take 18 months to produce the results it seeks.