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Two Postulates -- Special Relativity (1 of 5)



Uploaded by: dcolarusso
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Transcript: http://www.davidcolarusso.com/blog/?p=39#more-39
The Tabletop Explainer is an intermittent educational vlog presenting answers to viewer questions, brief science lessons, and ideas for teachers and students. It is a feature of my blog "Tilts at Windmils" which can be found at http://www.davidcolarusso.com/blog/


Tags for this video: education Einstein explainer physics postulates relativity science special tabletop

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Array ( 6 months ago by hilbert54)
RoadRunnerLaser
The speed of light is the same regardless of your relative speed.
Whether the emitter is moving toward you or away from you, or you are moving toward or away from the emitter, indeed even if you and the emitter are not moving relative to each other, you will measure the light as traveling at the same speed.
In which case, ... ( 6 months ago by RoadRunnerLaser)
In which case, Hilbert, as I stated in my first comment, a device which measures the journey time of a light-pulse will show the experimenter if he is moving relative to a static frame of reference. Thus, the first postulate is invalid because the constant speed of light will tell us our velocity and vector in comparison to a "fixed point". True ?
Array ( 6 months ago by hilbert54)
RoadRunnerLaser
If I get you correctly, the answer is in the video.
From about 2.15 to 3.15
You aren't supposed to look out the window to see a fixed point.
But even if you did, all you could say was you are moving relative to each other.
There are no fixed points in the universe with which to compare ones motion.
Yes if you marked a point on the ground and flew away from it you could show you were moving relative to that point, but that is why he goes on about falling asleep etc.
This video helped ... ( 5 months ago by rukajorn)
This video helped me understand the concept of special relativity for my a-level physics course, cheers for uploading it
Postulate 1 is ... ( 5 months ago by dasgregorian)
Postulate 1 is simple, and I'm fine with... but two beams of light traveling parallel to each other in the same direction cannot both be moving at "C" relative to each other. One will not observe the other going faster than it while the other observes the first going faster than IT.
I buy that light APPEARS to be constant, but the doppler effect shows it is not.
Photon A travels ... ( 5 months ago by dasgregorian)
Photon A travels away from it's source... The first observer isn't moving relative to the source and will see that photon at a certain frequency. A second observer moving relative to the light source will observe the same photon at a different frequency (red shift/blue shift). If frequency changed, this means one of two things. Either the wavelength changes depending on the observer... no. Or the speed of the wave is dependent upon YOUR speed relative to that wave.
Great vids ! good ... ( 5 months ago by Jernespand)
Great vids ! good job !
Special Relativity ... ( 5 months ago by kerpal2343)
Special Relativity exception. If you have a light and a proton speed detector that measures the speed of the light on the plane you can do the math and boom thats your speed.
THANKS.. THESE ... ( 5 months ago by mugwamp4)
THANKS.. THESE POSTINGS ARE GREAT..
a police car A is ... ( 5 months ago by independence8)
a police car A is chasing a car B, both travelling at 4/5 at speed of light, seperated by a distance of one light second. they both pass earth. what is this distance of seperation as seen by an observer on earth?
Exactly. If light ... ( 5 months ago by dasgregorian)
Exactly. If light is traveling at a constant speed relative to it's source, it's not traveling at a constant speed relative to anything moving relative to the light's source.
If a person moving at 99%C can see their reflection in a mirror normally, light is moving normally... whatever optical illusions you may detect... are illusions. An observer isn't going to suddenly experience time more slowly because YOU started running.
your objections ... ( 4 months ago by nialccmwr)
your objections only reflect a lack of understanding of relativity. it can be difficult to wrap your mind around it, but the assertions of relativity are true and without paradox or illusion. it's just that the conclusions aren't what we expect based on the world we're used to observing. if you chase light at 90% the speed of light, you will observe it moving away from you at the speed of light. non-intuitive, unexpected, odd, and true.
Thanks for ... ( 4 months ago by highburycatherine)
Thanks for uploading :)
Thank you so much ... ( 4 months ago by latewire)
Thank you so much for doing this, I wish more people would know science!
what if you kicked ... ( 3 months ago by peterthemegapimp)
what if you kicked the truck in reverse at 10 mph. would the photon move at 680,000,000 -10 mph, slower than the speed of light?
no. ( 3 months ago by coldfustion)
no.
this is sooooo good ... ( 2 months ago by libbeingcool)
this is sooooo good~~~
awesome~~~
i loved it
You rule. ( 4 weeks ago by Max11551)
You rule.
No. The speed of ... ( 3 weeks ago by Tetrahelix)
No. The speed of light is constant relative to the observer, not relative to a static frame of reference.
If that were true ... ( 3 weeks ago by RoadRunnerLaser)
If that were true then please explain how doppler shift is apparent in the light emitted from stars and galaxies travelling at significant speeds. If I understand this Universe correctly, there most certainly IS a "fixed point" - The ORIGIN - the point we're all rushing away from. The speed of light is fixed relative to that origin, by my understanding.
The equations of ... ( 3 weeks ago by Tetrahelix)
The equations of relativity do show Doppler shift when an observer is moving relative to the light source. This is not the result of the light moving faster or slower relative to the observer, but rather due to time dilation and length contraction. However, there is no absolute movement: all motion is relative.
If an observer were to use measurements of c to determine his or her speed, that observer would always find that he or she is at rest. This has been repeatedly confirmed by experiment.
I think that this ... ( 3 weeks ago by RoadRunnerLaser)
I think that this must be one of those "counter-intuitive" aspects of relativity, because as you say, observations would lead the experimenter to conclude that they are "at rest". It's one of those things that just when I think I understand, I suddenly realise that I've got hold of the wrong end of a stick from completely the wrong tree and not even from the right forest !
If I understand ... ( 3 weeks ago by 13248396)
If I understand this Universe correctly, there most certainly IS a "fixed point" - The ORIGIN - the point we're all rushing away from-heh thing is no matter were u are in the universe you will seem your are the center of the universe. Man in the moon would see himself has the center has phoenix in Mars seems to be the center of everything.Only way to explain it is if there is time dilation and length contraction.
anyone want to chat ... ( 6 days ago by frog1812)
anyone want to chat? hit up my page



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