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 #56323 - 09/05/16 08:40 PM Now you see it....... Bill S. Megastar Registered: 08/20/10 Posts: 3570 Loc: Essex, UK I may well present three scenarios in this thread; it, sort of, depends on the responses. In each scenario there is a hypothetical space craft, travelling at c and an astronaut on the craft with a flashlight which he shines from the back of the craft towards the front. There will also be one or two remote observers, with hypothetical instruments that can be turned on and off very quickly.(1) The astronaut turns on his flashlight. In his RF the light travels at c to the front of the craft.Observer A makes her observation as the astronaut turns on his flashlight. She sees no light. _________________________ There never was nothing. Top
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 #56327 - 09/05/16 10:52 PM Re: Now you see it....... Bill Megastar Registered: 12/31/10 Posts: 1858 Loc: Oklahoma, USA Ok, There is a problem with your first idea, that the space craft is traveling at C. It just can't do that. And if it could I don't think that the math would work. The space ship would wind up with an infinite (relative) mass. There is a form of math that works with infinities, but it isn't the type you use with Special Relativity (SR). SR uses just plain algebra. Bill Gill _________________________ C is not the speed of light in a vacuum.C is the universal speed limit. Top
 #56328 - 09/05/16 10:53 PM Re: Now you see it....... Bill Megastar Registered: 12/31/10 Posts: 1858 Loc: Oklahoma, USA By the way, did you mean this to be in the physics forum? _________________________ C is not the speed of light in a vacuum.C is the universal speed limit. Top
 #56329 - 09/06/16 01:56 AM Re: Now you see it....... Bill S. Megastar Registered: 08/20/10 Posts: 3570 Loc: Essex, UK Originally Posted By: Bill Ok, There is a problem with your first idea, that the space craft is traveling at C. It just can't do that.Someone had to point that out! Recall that Einstein had himself travelling at c, in order to make a point. I doubt that you would consider his conclusion invalid because of that. In his thought experiment, Einstein didn’t end up with infinite (relative) mass, that would only have detracted from his line of reasoning. Yes; I did mean to post in the physics forum. I don't know what happened there. I blame my age. _________________________ There never was nothing. Top
 #56330 - 09/08/16 12:40 PM Re: Now you see it....... paul Megastar Registered: 03/21/06 Posts: 4136 there is no physical reason why someone could not travel atc ... other than the capabilities of his propulsion system.and there is no physical reason why his propulsion system couldnot propel him to c.claiming that there is a limit to the speed of physical objects through the testing of the speed of light which has a speed limitthat is a result of its initial speed at the point of light emission and the speed and direction at which the light source is moving and the environment or medium that it then travels in is like saying that a bullet that is fired from a riffle under water from a fast moving submarine can not travel faster in the mediumof air above the water or even faster in the medium of space above the air.it is a untested pig headed claim.and that is all it is. _________________________ 3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science. Top
 #56333 - 09/09/16 12:38 PM Re: Now you see it....... Bill S. Megastar Registered: 08/20/10 Posts: 3570 Loc: Essex, UK OK Paul, so where does that leave you on the statements in scenario 1 (OP)? _________________________ There never was nothing. Top
 #56336 - 09/09/16 11:39 PM Re: Now you see it....... paul Megastar Registered: 03/21/06 Posts: 4136 you stated that the spacecraft and the astronaut and the flashlight were traveling at cso there must be a point somewhere that the speed measurement isbeing taken from as the spacecraft moves away from it at c.and were only talking about the light from the flashlight I suppose.so an observer traveling outside the spacecraft at c would see the same thing that the astronaut inside the spacecraft sees if there is a portal that he can look through , they both would see the light shining onto the front of the craft from the back of the craft.and if light detection devices are placed along the path of the craft then the light detectors should detect the same thing as the astronaunt and the outside observer are able to see given that the detectors are properly designed and calibrated to detect higher and lower frequency light because the craft will be moving towards and away from the detectors at c as the craft passes by them and the light from the flashlight will be traveling 1 x faster than c as the craft is approaching the detectors and 1 x faster than c as the craft is moving away from the detectors.so the detectors would need to adjust for the changes in light frequencythat enters into the detection portions of the detectors.like the red shift blue shift.if we focus on what our eyes can see then we end up with falsemath and a magic show to boot to sell books.https://www.youtube.com/watch?v=KJN5w9bMleM _________________________ 3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science. Top
 #56337 - 09/10/16 08:28 PM Re: Now you see it....... Bill S. Megastar Registered: 08/20/10 Posts: 3570 Loc: Essex, UK A common response to the OP from those who are scientifically inclined is simply to dismiss it because "nothing massive can travel at c", so it's an impossible scenario. An interesting factor is that there may be many more reasion why it could not happen. You have touched on some of the snags, and my reason for raising the topic was to point to another.The remaining two scenarios were as follows:(2) Astronaut acts as in (1).Observer A makes her observation when the light is half way from back to front. She would see it “frozen” in that position. (3) Astronaut acts as in (1).Observer A makes her observation as in (1). She leaves her instrument on, so sees no light.Observer B starts her observation at the same point as A, but has her instrument programmed to turn off and on again such that it comes on again when the light is half way from back to front. She sees, first, no light, then the “frozen” beam.Question: In the RF of an observer, does the light move only when it is not being observed?To me, this seems like “fantasy physics”. The conclusion seems inconsistent with reality as we observe it. I know that does not necessarily mean it cannot happen, our intuition is often a poor guide. I wondered what others thought. _________________________ There never was nothing. Top
 #56338 - 09/10/16 10:46 PM Re: Now you see it....... Bill Megastar Registered: 12/31/10 Posts: 1858 Loc: Oklahoma, USA Originally Posted By: Bill S.2) Astronaut acts as in (1).Observer A makes her observation when the light is half way from back to front. She would see it “frozen” in that position.I see a several possible replies. 1 Observer A would not see anything. Since the space ship is traveling at light speed it has zero length, with respect to the observer. Therefore it would be invisible. This assumes that the observer is off to the side of the trajectory of the spaceship.2 If Observer A was directly in line with the trajectory of the space ship then she would see a disc that represents the cross section of the spaceship all crushed together. If the space ship was transparent she would see the light moving along the spaceship trajectory.3 Observer A would see what appears to be a supermassive black hole traveling along the path of the spaceship, since the relativistic mass of the ship would be infinite.Bill Gill _________________________ C is not the speed of light in a vacuum.C is the universal speed limit. Top
 #56339 - 09/12/16 01:30 AM Re: Now you see it....... paul Megastar Registered: 03/21/06 Posts: 4136 since the spacecraft is traveling at c already none of the observers can "see" any light with their eyes except any observers that are traveling with the spacecraft at c and close to cthats why I used detection equipment ... our eyes could notsee light that is outside of the wavelenghts of the visible light spectrum.and if you add c to any wavelenght in the visible lightspetrum that wavelenght drops out of the visible lightspectrum. https://upload.wikimedia.org/wikipedia/commons/e/e4/Redshift_blueshift.svg _________________________ 3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science. Top
 #56340 - 09/13/16 01:30 PM Re: Now you see it....... Bill S. Megastar Registered: 08/20/10 Posts: 3570 Loc: Essex, UK Although the original scenario is impossible, a thread like this throws up some fascinating thoughts, for me, that is its value.Originally Posted By: Bill If Observer A was directly in line with the trajectory of the space ship then she would see a disc that represents the cross section of the spaceship all crushed together.A few thoughts arise from this. 1. If the ship is travelling at c, observer A would not see the disc until it hit her. 2. If the ship is infinitely length contracted, it has no length. Can it be said to exist?3. If the ship has a "headlight"; in the RF of the observer, the light and the ship would reach her at the same time. However, in the RF of the astronaut, the light would be leaving the ship at c. Does this mean that the astronaut would see the observer, but she would not see the ship? _________________________ There never was nothing. Top
 #56341 - 09/13/16 01:36 PM Re: Now you see it....... Bill S. Megastar Registered: 08/20/10 Posts: 3570 Loc: Essex, UK Originally Posted By: Paul[/quoteand if you add c to any wavelenght in the visible light spetrum that wavelenght drops out of the visible light spectrum A valid point, Paul. The more you think about a scenario like this, the more reasons you find for labeling it "impossible". _________________________ There never was nothing. Top
 #56342 - 09/13/16 04:35 PM Re: Now you see it....... paul Megastar Registered: 03/21/06 Posts: 4136 A few thoughts arise from this. 1. If the ship is travelling at c, observer A would not see the disc until it hit her. if observer A is not moving in reference to the point that the speed measurements are taken from to obtain the speed of thespacecraft then observer A would never see the spacecraft.unless his / her eyes can detect the light from the flashlightmoving at 2xc and the only light that is available for any observer to "see" is the light from the flashlight that is moving at 2xc 2. If the ship is infinitely length contracted, it has no length. Can it be said to exist?there is no physical reason for the spaceship to be contractedin length.so fake math and illusion or not the ship would exist and wouldnot contract in length or width or anything unless there is a force that crushes the spaceship and no force of that magnitudehas been included.3. If the ship has a "headlight"; in the RF of the observer, the light and the ship would reach her at the same time. the light from a headlight traveling at 2xc would reach the observer first followed by the ship that is moving at 1xc.she (her eyes ) would never "see / detect" the light or the ship.and would never feel the impact.unless her pain receptors send signals to her brain faster than c and her brain processes that data faster than c.However, in the RF of the astronaut, the light would be leaving the ship at c. Does this mean that the astronaut would see the observer, but she would not see the ship?even though the astronaut can see the light "inside " it is only because he and the ship are traveling at c , he would not be ableto see any light reflections that would reflect off of observer Afrom the headlights.the astronaut would never "see" the observer because he ismoving towards the observer at 1xc and any light reflecting offof the observer would be traveling at 1xc which adds up to 2xchis "eyes" cannot detect light below the visible light spectrum. _________________________ 3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science. Top
 #56343 - 09/14/16 02:56 AM Re: Now you see it....... Bill Megastar Registered: 12/31/10 Posts: 1858 Loc: Oklahoma, USA Originally Posted By: Bill S.1. If the ship is travelling at c, observer A would not see the disc until it hit her. Observer A might be behind the ship.Originally Posted By: Bill S.2. If the ship is infinitely length contracted, it has no length. Can it be said to exist?It must exist, since it has infinite relativistic mass. But just how it would exist is a problem. That's what happens when you try to think about things that can't really happen.Originally Posted By: Bill S.3. If the ship has a "headlight"; in the RF of the observer, the light and the ship would reach her at the same time. However, in the RF of the astronaut, the light would be leaving the ship at c. Does this mean that the astronaut would see the observer, but she would not see the ship? In the RF of the ship Observer A would be traveling at the speed of light. So the problems would be reversed.Bill _________________________ C is not the speed of light in a vacuum.C is the universal speed limit. Top
 #56348 - 09/19/16 07:41 PM Re: Now you see it....... Bill S. Megastar Registered: 08/20/10 Posts: 3570 Loc: Essex, UK Originally Posted By: Bill Observer A might be behind the ship.In which case she would never see the ship, or even know it was there. Here I use “see” with due deference to Paul’s comments.Quote: It must exist, since it has infinite relativistic mass. But just how it would exist is a problem. That's what happens when you try to think about things that can't really happen. True, but I’m quite happy with that, as I was looking for/at reasons why massive objects might not be able to accelerate to c. As you might suspect; the concept of infinite relative mass interests me. I’m trying to get my head round all that it implies. Quote: In the RF of the ship Observer A would be traveling at the speed of light. So the problems would be reversed.So neither would see the other, and both would measure the speed of the headlight as c; except that they would not “see” it, so could not measure it.As you say: that's the problem with impossible scenarios. _________________________ There never was nothing. Top
 #56351 - 09/22/16 01:06 AM Re: Now you see it....... paul Megastar Registered: 03/21/06 Posts: 4136 Quote:except that they would not “see” it, so could not measure it.If they ever begin to use propulsion systems that could cause aspaceship to travel at c and beyond they could use somethingsimilar to the einstein bose condensate to "see" where theyre goingwhile traveling at and beyond c but I would imagine? that em wave sensors would be used in conjunction with navigation systems to avoid hitting large objects that would not be deflected by the bow shock or whatever means of deflection they decide to use.lets just hope that they have tossed the junk science in the trash can long before they achieve c speed flight. _________________________ 3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science. Top

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