Who thinks Faster Than Light travel is possible?

Both Zero and Negative Numbers are abstract concepts and do not truly exist in the physical world. Distance and Time are relational concepts and need a baseline and something outside the baseline to compare against.
The square root of -1 doesn't exist either, but many a physics and mathmatical solution rely it's existence.

As in

e ^ (i x Pi) - 1 = 0

for a starter.
 
The square root of -1 doesn't exist either, but many a physics and mathmatical solution rely it's existence.

As in

e ^ (i x Pi) - 1 = 0

for a starter.
Hm... All numbers can be derived from Natural Numbers (0,1,2,3,4,5....). Example is if you can add numbers together then you can do the opposite operation of subtraction and get negative numbers. This gives you Integers (... -2, -1, 0, 1, 2 ....). By similar arguments we get other types of numbers. The start of the list is:
  1. Natural Numbers
  2. Integers
  3. Real Numbers
  4. Complex Numbers
  5. Quarternions
  6. Octonions
  7. etc
I very doubt that without Quartonions we would have ever been able to come up with matrix theory, which of course was more or less essential in identifying the rules of Quantum Physics.
 
I wrote 3 posts about this. 60% C in one direction and 60% C in.the opposite direction is 120% C. But no one object is going faster than light.
I am not sure that those numbers are additive, certainly not without changes in frame of reference. One cannot say an object is moving at both 60% C and 120% C. If one changes from the frame of reference of the center point to that of one of the outer points, it is my understanding that time dilation or some other effect ensures that, from that frame of reference, the speed of light is not violated.
 
I am not sure that those numbers are additive, certainly not without changes in frame of reference. One cannot say an object is moving at both 60% C and 120% C. If one changes from the frame of reference of the center point to that of one of the outer points, it is my understanding that time dilation or some other effect ensures that, from that frame of reference, the speed of light is not violated.

I am reaching the limits of my understanding here. My initial thought was that you are correct. No two objects can move apart at greater than the speed of light in any single frame of reference. However, @msstice (I think it was) gave us the example of the observer being offset from the line of trajectory of the objects. Say hundreds of light years away, observing from a point perpendicular to the direction of motion from the origin of the objects. In this case, surely we would indeed see 1.2 light years increased distance between the two objects when we make two observations one year apart? I think this was what @Swank was referring to when he talked about us moving our eyes in a moment, from one distant object to another(?). It remains true that no object can move at greater than the speed of light relative to the observer.
 
I am reaching the limits of my understanding here. My initial thought was that you are correct. No two objects can move apart at greater than the speed of light in any single frame of reference. However, @msstice (I think it was) gave us the example of the observer being offset from the line of trajectory of the objects. Say hundreds of light years away, observing from a point perpendicular to the direction of motion from the origin of the objects. In this case, surely we would indeed see 1.2 light years increased distance between the two objects when we make two observations one year apart? I think this was what @Swank was referring to when he talked about us moving our eyes in a moment, from one distant object to another(?). It remains true that no object can move at greater than the speed of light relative to the observer.
I think the confusion may arise from trying to convert distance into velocity. This requires a shift in frame of reference, which is inconsequential at non-relativistic speeds. Trying to add 0.6 C to 0.6 C to get 1.2 C is shifting from a neutral observation point to the frame of reference of one of the moving objects. Due to time dilation, that point will not observe a speed of 0.6 C from the neutral point nor a speed of 1.2 C from the other moving point.

Putting some numbers on my initial confusion. The universe is currently assumed to be slightly less than 14 billion years old. The diameter of the universe is supposed to be 93 billion light-years. To me, the size should be limited to less than 28 billion light-years if it was expanding at the speed of light. This would suggest that the outer edge of the universe (whatever that might mean) needed to travel at an average rate of 3 1/3 C.

I admit that I do not understand this and I have read several explanations, which I also failed to understand. It does seem to imply that relative motion beyond the speed of light is possible. I may be guilty of using math, especially with regards to time dilation, incorrectly, but I am not seeing my error in analysis.

References:
 
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I am not sure that those numbers are additive, certainly not without changes in frame of reference. One cannot say an object is moving at both 60% C and 120% C. If one changes from the frame of reference of the center point to that of one of the outer points, it is my understanding that time dilation or some other effect ensures that, from that frame of reference, the speed of light is not violated.
I think one can say that this event and this other event can be related to each other in our minds without breaking a physical limit. We are just creating this relationship, not observing an actual rate that something is moving. I think observer effects and Lorentz diagrams cause some confusion as to how relative everything has to be. But if you are the origin of both sets of movement, you can speak about their sum movement in relation to your (relatively) static starting point without there being a paradox.

If Neptune and Saturn happened to be about equal distance from earth due to their orbits, and we fired a laser at both at the same instant, we would see the reflected light from both at the right number of minutes later that is the light minute distance from earth to Jupiter and back to earth, and we would see the same from earth to Neptune and back. The fact that we lased Neptune at the same time that we lased Jupiter doesn't change the distance that either laser traveled, and if we sum the distance the light traveled to Jupiter and Neptune that sum does not represent a total distance that light traveled, but two light beams traveling at the same time.


All of which is useful here in our local galaxy group, where universal expansion is not a factor. The current cosmological model says that the very large spaces between galaxies are growing not in simple distance, but that actual spacetime is growing. This is not the fault of the weird relativistic way we have to deal with lightspeed and time dilation, but that some natural process creates space between places at a rate that exceeds the ability of light to cross it.

This theory requires dark mass and dark energy which we know nothing about, and is ultimately linked to how we have observed the speed of distant objects via redshift. However, while redshift makes very far objects appear to be riding this expansion wave at a very high rate, the dimming of their luminosity is not. In other words, a galaxy so distant that it has doppler shifted to that degree should also be less bright, and that doesn't seem to be happening. Which is not to say that our current expanding universe model is wrong, but it would not be shocking if it turned out the red shift is not due to expansion after all and the distances we are computing due to red shift are wrong.


So you aren't going to better understand the light speed limit problem by trying to understand the expansion of the universe. Light speed limits aren't dictating what we observe in terms of expansion - light is just as confounded as we are by this extra force of nature. And locally we can treat light in a mostly Newtonian way, as long as we keep an un-accelerated reference frame to make our statements about what is happening.
 
It is somewhat annoying when you cannot prove true stories but:

I was a college freshman majoring in electrical engineering. I had just read Tau Zero by Poul Anderson. I went to a senior physics major in the fraternity to discuss saying I really didn't understand what was going on with Einsteinian physics.

He said, "You don't try to understand it. You memorize the equations and how to apply them."

Since I have never seen a practical application for my truly understanding near light speed physics I gave up on it. But I do wonder how many people with physics degrees really do.
 
Not too sure about that. Time is a property of our universe. Therefore it has no context unless the universe exists. Cause and effect is also a concept that relies upon time for meaning.
The seems to be a school of thinking that time is kind of an emergent property from events. I think the question of whether there is still time when there are no events or observers is, I feel, a significant one.
I might even have a -pre big bang story- idea brewing here: "The Loneliness of the Unwatched Clock." :unsure:
 
Lets say I have a shinny new FTL ship and I go for lunch at Alpha Centarie. Say I get there in just a few hours (by my watch).... when I am at Alpha Centarie, the light I see from the Sun left 4 years before I did. The light being emitted by the Sun is still another 4 years further behind that.
After lunch I decide to go home right away. Again lets say this takes just a few hours.
When I get back to Earth it will be 8 years before I left.
 
The universe is currently assumed to be slightly less than 14 billion years old. The diameter of the universe is supposed to be 93 billion light-years. To me, the size should be limited to less than 28 billion light-years if it was expanding at the speed of light.

I'm curious about this. Is the 93 billion light years an extrapolated number? I mean, if I look at an object 100,000 light years away I am seeing it as it was 100,000 years ago. I can work out its velocity relative to my position by checking the Doppler shift in the light coming from it. I can then extrapolate a position for it right now (the position it was observed in plus velocity x time). Has such extrapolation been used in calculating the universe is 93 billion light years across?

What I'm struggling with here is perhaps philosophical. As the object can have no effect on me (other than in the position I observe it) can it really be understood to be anywhere else?
 
The seems to be a school of thinking that time is kind of an emergent property from events. I think the question of whether there is still time when there are no events or observers is, I feel, a significant one.
I might even have a -pre big bang story- idea brewing here: "The Loneliness of the Unwatched Clock." :unsure:
This might be related to the concept of entropy. The energy in the Universe is gradually being equalized. Warm things impart heat to cool things. Moving things hit each other - their energy being redistributed. Chemical energy is released through reactions. Eventually, every point in space will be at the same energy and literally nothing will be happening. The question is; does time still exist (and how can we even tell).
 
Since I have never seen a practical application for my truly understanding near light speed physics I gave up on it. But I do wonder how many people with physics degrees really do.

"Understanding" is a deceptively difficult word.

All through graduate school I, along with some other classmates, wrestled with the age old question of what it means to "understand" something. After graduate school, I still did not understand what it mean to understand, but I marched on.

I think when we say we "understand" something, it means we've memorized (internalized) the steps needed, or pointers to the steps needed, to answer a question about something. We have a mental model (probably with pointers to external knowledge) of the thing in question.

I understand the oven in my house. If I need to bake something, I put it in the oven and turn on the switch.

When the oven element burned out, I stretched my understanding of the oven, by realizing it is the oven element that heats the oven. I understand that electricity flowing in the metal heats it up and this heat radiates or convects to the rest of the oven.

The higher the current, the more the number of electrons "flowing" in the wire. The electrons agitate the atoms in the metal, which vibrate and that is heat.

Now my understanding is breaking down. Are electrons little billiard balls that bounce around the metal? That model kind of works, but people have found cases where it doesn't.

Is heat the vibration of atoms/molecules. Yes, but I've heard people think of heat as information.

At some level, when the thing is complex enough, or far enough from everyday experience, we can't mask the illusion of understanding, and have to admit: I just work out the equations.

Many of you will know this as the great physicist throw down of the last century between Einstein and Bohr complete with Einstein's catch phrase "God does not play dice." which he said every time he tossed Bohr on the mat and did a pile drive. I may have made that last bit up.
 
@Christine Wheelwright

The problem I havewith the old red shift thing is what was the source.

With all the hoo har about the JW eyeball in the sky thing is they've set their detectors to detect things in the IR frequencies because - They say - The objects they are observing were originally super bright ultra violet suns and because of the speed/red shift effect the frequencies will have been toned down.

The trouble I have is what's to say that what they are actually observing are IR sources that have been traveling across a much larger space for a much longer time.

I.E. Whats the difference between a UV source red shifted and a plane old IR source?

As for the 93B light years across surely that is just bunkum unless a light year now is less distance than a light year way back when.

Oh wait that would mean....
 
"Understanding" is a deceptively difficult word.

All through graduate school I, along with some other classmates, wrestled with the age old question of what it means to "understand" something. After graduate school, I still did not understand what it mean to understand, but I marched on.

I think when we say we "understand" something, it means we've memorized (internalized) the steps needed, or pointers to the steps needed, to answer a question about something. We have a mental model (probably with pointers to external knowledge) of the thing in question.

Graduate school in what subject?

I was one of those kids that thought mathematics was fun. The nitwit nuns I had in 8th grade gave us an algebra book but did not teach the subject. My older sister was in high school and her trigonometry book looked more interesting than my algebra book so I started teaching myself trigonometry.

I will admit that trying to explain the difference between memorizing and understanding to someone else is a problem but it is like I can feel it in my brain when the transition happens. The solutions to problems become obvious instead of following a recipe.

I had a mathematics teacher my junior year in high school who would assign homework but only intermittently collect it. Part of our grade was dependent on homework so it became a game. If I didn't do it and he didn't collect it I won. If he did collect I lost. It didn't really matter since I always got an A on the tests so the worst that happened was I got a B that grading period. I think I pissed him off because I didn't care.

But the people who just memorize must pretend that they understand. Sometimes you can catch them on the basis of their mistakes.

That is what pisses me off about the Twin Towers Affair. Look at the shape of the 10,000 tons of wrought iron down the Eiffel Tower. The lower portions must be strong enough support all of the weight above. So it increases exponentially.

Where is the data on the distributions of the 100,000 tons of steel and the never specified tons of concrete down the North Tower? The straight down collapse cannot be understood. Only believed by some people.

The memorizers are unlikely to go beyond Einstein. Whoever does will almost certainly understand.
 

Under the rules here I can only skirt.
But I have to eat humble pie when I look at the state the world is now in.
Retrospectively, the 'foil hatters' were right on just about everything, and probably will be going forward.
 
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Getting back on topic seeing as the original discussion about relatively has burned itself out...

Is it my imagination, or didn't I read a while back that synchrotron radiation effectively requires electrons to travel FTL, just not in a linear way?
 

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