/sci/ - Science & Math

It will read "you're a fucking faggot, kill yourself".

>>10003832
you need to go back to pol.

>>10003820
As I recall, you were answered, several times, you just didn't like the answer. Can't help you there for the same reason we can't help flat earthers.

In anycase, the answer is lightspeed, or zero, depending on how magical your radar gun is - which is pretty magical, since it can't be made of matter, the forces that make up matter only propagating at the speed of light and all, and said matter couldn't exist were that not the case. Frame transformations get wonky at relativistic speeds, and go straight out the window at c.

Some shit that might help it click one day:
https://www.youtube.com/watch?v=msVuCEs8Ydo

https://van.physics.illinois.edu/qa/listing.php?id=2605

>>10003820
It will measure the same as if you stood still and the second train was moving from you at near the light speed.

>>10003848
So if a train rides 400miles/h, and another one 400 in the opposite direction, it would measure 800miles/h.

But if one travels 400.000.000miles/h, and the other also 400.000.000 in the opposite direction, it would only measure 670,616,629 miles/h, for some magical reason.

And really all of modern physics is based on this obviously wrong and bullshitty axiom?

Spacetime deforms as you reach light speed, the distances and time between the two trains would alter in such a way that the max speed you would see the other going is always light speed irrelevant of your speed.

>>10003863
>obviously wrong
But it's not wrong anon. Every expirimemt done so far has only proven it right. If you can provide it wrong you'll get a Nobel Peace prize.

>>10003820
>I sit in a train riding 100mp/h
160.9 in non-retarded units, i.e. km/h.

>and another train passes by travelling with the same speed into the opposite direction. I now take my radar gun and check the other train's speed, and it will tell me that train is travelling with 200mp/h. Right?
No, it would be [math]200\cdot (1-2.22\cdot 10^{-14}) [/math] mph.

>So let's say that my train is moving with close to lightspeed, and so is the other train. What speed will the radar gun measure?
"I don't understand Special Relativity, thead number 10379".

>>10003863
>And really all of modern physics is based on this obviously wrong and bullshitty axiom?
Because it works. If you don't understand SR is not our problem.
Also, it wouldn't meassure 800 mph. It's a little bit less [math]800\cdot (1-3.588\cdot 10^{-13}) [/math].

>>10003884
Please point to me one experiment that proves that nothing can move faster than the speed of light. Thank you.

>>10003887
https://en.wikipedia.org/wiki/Tests_of_special_relativity

If you always simply chose not to accept what you did not understand, you would still believe your mother ceased to exist when she played peekaboo with you.

It does make me wonder what is the typical rational-breaking experience that produces people like this is, and how we go about undoing it, or making sure it happens less often, if it cannot be undone.

>>10003887
https://en.wikipedia.org/wiki/Kennedy–Thorndike_experiment

>>10003820
There's an addition formula for velocities that get close to light speed, you'll just read that the other train is going really really close to light speed, but still not over it.

https://en.wikipedia.org/wiki/Velocity-addition_formula#Special_relativity

>>10003893
legalize LSD, mandatory for all 18 year olds, recycle the biomass of the ones who go crazy

Okay, so I need to understand this.

Supposed pic related are two train tracks. On each, there is a train driving 400.000.000miles/h into the direction indicated by the arrows. The red portion of the track is where they would drive parallely into the opposite direction of each other.

1. If you could only measure something very close to the speed of light, which trains velocity would be reduced?
2. What is going to happen after the portion of the track where they move directly parallel to each other ends? Is(Are) the train(s) going to accelerate back to 400.000.000miles/h, or are they permanently reduced in their velocity, and you would need to re-accelerate them to bring them back to 400.000.000, and as soon as they drive parallel to each other, their velocity would again magically go down?

>>10003917
Forgot the pic

>>10003917
>parallely

>>10003917
Forgot the pic

>>10003917
Depends on which frame of reference you are observing from:
https://www.youtube.com/watch?v=kGsbBw1I0Rg

>>10003920
>>10003924
>>10003925
Go to bed George, you are drunk.

(Also you should entitle it "Maxwell_Fraud" - as well as the millions of other physicists that tried to kill his work, but couldn't, and the millions more of undergrads that run tests on SR every semester, and apparently lie about the results, just to keep it going.)

>>10003917
to
>>10003925
You have proven that your cognitive ability is going down the toilet.

>>10003933
Not that guy, but that doesn't answer any of the questions.

>>10003945
>which trains velocity would be reduced
It should at least tell him that isn't how it works, and involves a similar train "paradox".

>>10003945
i think that's because we're all hoping the question is bait

nothing is wrong with 2 objects moving past relative to each other faster than the speed of light. if that's the issue, he should try google first

>>10003964
so, apparently not bait, because a new thread was started

i'm not being mean, but it seems like all of your knowledge was based off of something a friend told you or one youtube video. that's not bad, just don't expect conclusions you make from that to make sense at all. do stuff like that for fun...don't expect it to make any practical sense.

>>10003964
>nothing is wrong with 2 objects moving past relative to each other faster than the speed of light

Calling other posts bait and posting something like this is the real bait. I bit though, so congrats.

>>10003977
you sound serious, and that annoys me

>>10003977
it's not bait. i'm a quantum physicist. you think i don't know relativity?

special relativity is all geometric, and the only limit is the absolute speed limit of c in an inertial reference frame. objects, relative to any other object, can move as fast as they want

>>10003981
According to your post, something not moving at all, and something moving with greater than speed of light past it, would also be okay, brainlet.

>>10003982
>i say it's not against the law just to move your hands
>you say "according to your post, you could move your hands in a way that kills everyone and it's not against the law"

>>10003863
>And really all of modern physics is based on this obviously wrong and bullshitty axiom?
>I DONT LIKE THE ANSWER SO ITS BULLSHIT

>>10003991
Are you retarded or something? The correct answer to OPs question is spacetime-dilations, not your retarded bullshit.

>>10003998
spacetime-dilations? what are those? as a physicist, i haven't heard of that term
i've head of time dilation, but that's a geometric effect which is what i said

>>10004003
>what is lorentzcontractions
>what is spacetime curvature

Youre a brainlet that doesnt get Einstein. You have already proven that with this retarded comment >>10003964

>>10004009
ok, i agree with every single thing you said, but still never heard of the term "spacetime-dilations" and am really curious what those are

>>10003820
>travelling with 200mp/h. Right?
wrong, assuming it's accurate

>>10003981
>i'm a quantum physicist. you think i don't know relativity?
I've seen a lot of quantum physicists writing "I can go to the frame of reference in which the photon is at rest without loss of generality" in exams a lot of times....

>and the only limit is the absolute speed limit of c in an inertial reference frame
Yes.

>objects, relative to any other object, can move as fast as they want
No. By changing the frame of reference you can change the speed of objects moving below the speed of light to any speed below the speed of light. You can do the same with the speed of objects moving above the speed of light to any speed above the speed of light. But (unless you change to a frame that is moving at a speed greater than c with respect to you) you can't make objects slower than the light go faster than the light and vice-versa.

Lots of brainlets ITT. Had relativity be "proven", there would be a nobel prize for it. But, there wasn't. This is also why Einstein got one for his work regarding photons, but not one for his relativity theories.

Also, all experiments regarding "prooving" that speed of light is constant only prooved that the velocity of waves are constant. You can redo them all with sound waves, and have the same results.

>>10004532
>muh Nobel
https://en.wikipedia.org/wiki/Tests_of_general_relativity
https://en.wikipedia.org/wiki/Tests_of_special_relativity

>Also, all experiments regarding "prooving" that speed of light is constant only prooved that the velocity of waves are constant. You can redo them all with sound waves, and have the same results.
LOL if that were true then sonic booms couldn't exist. The speed of sound depends on the observer, the speed of light does not.

>>10004652
Sonic booms occurs when you are faster than the speed of sound, you brainlet, this has nothing to do with what I said. The speed of sound is as constant as the speed of light.

>>10004664
>Sonic booms occurs when you are faster than the speed of sound, you brainlet, this has nothing to do with what I said.
It has everything to do with it, brainlet. The speed of sound depends on its source, the speed of light doesn't.

>>10004664
So you admit relativity is proven, good.

>>10003908
we do have a phosphorus shortage, would help that out immensely

>>10004664
>The speed of sound is as constant as the speed of light.
Demonstrably false. The speed of sound is dependent on the speed of light AND the distance between the particles that the sound propagates through. It's why sound travels faster in water than in air; the particles, on average, are closer together.

More in context, the air INSIDE your jet isn't going to have a sonic boom because it's moving at the same speed as the jet. However, if you're in a near-lightspeed ship, the light from outside will be moving at the same speed as the light inside. If it didn't, normal matter would completely flatten & atomize at faster speeds because the electromagnetic force would get weaker because the carriers of the electromagnetic force are massless, and all massless particles travel at exactly c.

>>10003820
>So let's say that my train is moving with close to lightspeed, and so is the other train. What speed will the radar gun measure?

It will read "close to lightspeed."

>>10003884
>f you can provide it wrong you'll get a Nobel Peace prize.

More likely a Nobel in Phsyics.

>>10003945
It does not answer the questions, it points out that the questions are nonsensical without giving more information -- which frame of reference are you in, as the observer. The questions are nonsensical on several other points, but the frame of reference not being specified is the one >>10003933 addressed.

>>10003820
>So if I sit in a train riding 100mp/h, and another train passes by travelling with the same speed into the opposite direction. I now take my radar gun and check the other train's speed, and it will tell me that train is travelling with 200mp/h. Right?
only approximately. if both your train's speedometer reads 100 mph and the other train's speedometer reads 100 mph, then your radar gun fired at the other train will be actually slightly less than 200 mph, but such a small correction that it's a very tiny difference

>So let's say that my train is moving with close to lightspeed, and so is the other train. What speed will the radar gun measure?
here the correction gets substantial (rule of thumb: for speeds greater than 0.9 * lightspeed). your radar gun will measure the other train as going slightly less than lightspeed, but faster than what the other train's speedometer reads

>>10004720
It absoluetely doesn't, you brainlet, because that's not how waves work.

>>10004733
Light also travels slower in water, brainlet.

>>10003917
Nobody here is saying that either would be measured less than 400 million mph.
It's just not 800 million. Theres no acceleration involved

>>10003981
Show the math. If you've done any hep stuff in qm like you claim, you would be familiar with the basis changes and know it's not possible mathematically. So unless you have something else that shows otherwise you should think twice before claiming to know something

>>10004772
The reference frame is completely clear if you read the OP. He sits in one of the trains and measures the other train from insde the train.

>>10003820
>I now take my radar gun and check the other train's speed, and it will tell me that train is travelling with 200mp/h. Right?

No, the radar gun would read 100 mph. 200-100=100

Time slows down and space expands to compensate so the radar travels at c, and the speed will read the sum of the 2 trains. Speed of light isn't effected, and neither train exceeds c.

>>10003981
This is correct.

>>10004014
>What are dilations in space-time.
Good Lord, idk how much intro to physics students I can handle.

>>10006114
>What are dilations in space-time.
i have that question but unironically

>>10006529
The language in which the theory of relativity was conceived in (german) calls them Raum-Zeit-Verkrümmungen.

>>10006535
i wish i could learn relativity from the original papers in german

>>10004862
The actual photon isn't slowing down in water, brainlet. The light is using time getting absorbed and re-emitted, and also because of that, the light isn't even traveling in a straight line through water.

2 satellites in fixed orbits 1 light year away from earth and 2 light years away from each other so all three are on a straight line. Radio waves take 1 year to get to earth, and 2 years to the conjugate satellite. A burst is sent from each satellite at the exact same time, reach earth in a year and continue to the opposite satellite. After 1 year, from earth the velocity between each burst is 2c. If it wasn't one burst would get to the other later than 2 years, which one slows? Neither, it is absurd to think one slows down because the other is already going light speed. The 2c between the bursts doesn't violate c, each goes its merry way.

>>10003820
>So if I sit in a train riding 100mp/h, and another train passes by travelling with the same speed into the opposite direction. I now take my radar gun and check the other train's speed, and it will tell me that train is travelling with 200mp/h. Right?
>>10003863
>if a train rides 400miles/h, and another one 400 in the opposite direction, it would measure 800miles/h.
NO.
If your measurements are accurate enough you will spot a discrepancy. Relativity explains this discrepancy.

>>10006792
What do you think sound is doing, brainlet.

>>10003846
>oldest 4chan meme ever is /pol/
Holy shit, we're hitting levels of cringe that shouldn't even be possible.
When did /sci/ become so retarded that everything's /pol/?

>>10006792
...not, exactly...
https://www.youtube.com/watch?v=CiHN0ZWE5bk

>>10003820
You won't get a reading because thoughts and chemical processes wouldn't happen at light speed you'd dissociate into elementary particles

>>10003863
>And really all of modern physics is based on this obviously wrong and bullshitty axiom?

It is not an axiom, it has been empirically proven multiple times, you moron.

question already been asked and answered by scientists before, use google you idiots.

You would get a reading of 400 mph in the trains, and in the case of light speed the temporal dilation would fuck with your perception of the other object so that the speed readout would still be at or less than the speed of light

>>10003820
your radar won't work because your beam would be blue-shifted to a wavelength that has enough energy to destroy any material it encounters instead of reflecting back to you to allow you to measure time delay between two pulse and hence determine speed...

>>10009946
You're smoking crack. At most you'd double the frequency, and for radar, that still radar.

>>10003863

If there's a meme axiom you want to pick a beef with, why not Conservation of Energy?

>>10007364

Probably when that guy had a bot on here posting climate change skepticism and flat earther memes for over two years.

>>10007364
After they got BTFO'd by race realists, they have became obsessed with /pol/.

>>10010580

>>10010610
lel

>>10010574
but conversation of energy speaks on erry level of ervy observable interactionn

unlike da universal speed limit which cannever be observed

more like, wat if da photon is limited by the medium it traveleds thorugh and that is the speed o light. O wait the light is the medium... dum theory for dum ppl

>>10007311
If the earth isnt moving relative to the satellites during the signal travel from earth's frame, then you see two different signals each going at 1c. It is meaningless to say the velocity of the signals relative to each other is 2c as observed from earth, which is what you did. It's just 2 signals moving at 1c each.

>>10010610
I knew /sci/ was getting progressively more based as time went on, even with the influx of Redditfags

>>10011036
That's what I was trying to say. Each wave is traveling at c. But if you measure the magnitude of the resultant vectors, you will get 2c.

>>10011735
Are you fuckinf retarded or something? Thats not at all what this thread is about.

>>10012000
The point was that the radar gun would read the sum of the trains velocity, and that would be greater than c. Nothing is violated . If they were traveling at c, then the radar gun would read 2c. If they were traveling at .75c then the radar gun would read 1.5c. The point was even at the limit at c, the velocity between the 2 waves is 2c but each wave is going at c, nothing is violated.

>>10012864
Yes, it would be violated, you dumb fuck. It is absoluetely impossible that we ever, under what circumstances so ever, are going to measure something going faster than c. You obviously did not understand relativity in the slightest. For the reference frame of the train, it makes no difference if its going 0,9c, and the other train is going 0,9c, or if the train is at rest and the other is going 1,8c.

>>10012876
False. Two trains leave earth going 0.9c away from the earth in directions 180 degrees apart. In one year, the will be exactly 0.9 light years away from the earth and 1.8 light years distance between the two. Velocity is distance divided by time. 1.8c / 1 is 1.8c. Now do the reverse, measure the velocity between the trains. It has to be 1.8c, because you know that each train traveled at 0.9c for 1 year. Nothing can travel faster than c, yes, but that's not a limit on measured velocity between two object. It's not possible for 1 train to be at rest and the other at 1.8c, that's a violation. The radar coming from the train would appear to be higher frequency from the opposite train, and the return radar would be be the original.

Two particles traveling at 0.9c in a particle accelerator toward each other, start at 0.9 light years away from each other. You know they are 1.8 light years apart, and must meet in the middle where you are at because they are traveling at 0.9c, what's the velocity between the 2? If you say anything less they won't meet in the middle, in one year. Special relativity does not prevent this. Neither are going faster than c, nothing is violated. Look up relativistic closing speeds.

>>10013419
You are looking from the third observer, you dumb fuck.

>>10013429
Radar guns work on doppler which is a change in frequency, not velocity. A doubling of frequency, would read as doubling speed. If the phase velocity is constant, which it is.

>>10013454
Stop distracting from the fact you dont understand the fundamentals of relativity. Your post have clearly shown you dont get it.

>>10013462
I understand general relativity just fine. The radar gun will show 1.8c. None of the three will see any velocity greater than c. But the two trains are approaching each other at 1.8c. That is unassailable.

>>10013471
They are, from a third observer, not from each other. You don't get relativity at all.