Help-a-Brainlet charity thread

time dilation

>>9052507
There's several reasons why nothing with rest mass can go ftl. If you could go faster than light, you'd reach your destination before the light that left at the same time as you did so you'd effectively be from the future. But, you can't actually go back in time.

>>9052517
>reach your destination before the light that left at the same time as you did so you'd effectively be from the future
What makes light special though?
If you ran faster than the speed of sound you'd get to your destination before the sound waves and be able to hear yourself coming but no one says that's impossible or makes you're a time traveller.

>>9052530
There isn't anything special really except that how fast you're moving affects how time moves for things around you.

When special relativity was discovered, we had to choose to keep conservation of energy or fixed time. We chose to keep conservation

>>9052507
At that speed, conventional forces to propel the matter cannot exist. Nothing can provide enough energy to get something with any level of mass moving that fast. Nobody seems to be addressing that. The issue is not, theoretically, whether mass can exist at such speeds, but actually whether or not the force exists to push mass to that speeds and it does not.

>>9052507
Time doesn't exist. You can never "go back in time".

Sage because you are so inept and new you can't use the catalog: >>9039057

>>9052507
The concept of speed is confusing in nature. For my point of view it's harder to understand the speed parameter then speed limit.

Start with restricting the same object from present is different points of space at the same time. After that it's easy to understand that there is a minimal amount of time that will elapse when object move from one point to another. This minimum amount of time can be use to measure the 'speed'. Divide the distance between the points by the minimal amount of time and you will get the maximum speed possible in system with restriction mentioned above. Speed wave or photons are the entities that capable to travel with this maximum speed.

Did I made it clearer?

A lot of strange pop sci talk here.

There are two limites:
- you cannot accelerate mass from below to above the speed of light
- you cannot transmit information faster than the speed of light

That however is not an objection to tachyons. And these by defision have v > c.

>>9052820
which don't exist

>>9052530
>What makes light special though?
Probably that you have to observe your surroundings in order to determine if you're going forward or backward in time, and if you're seeing a "disordered" (high-entropy) environment becoming more ordered then you'd have a pretty good justification for concluding that you're travelling back in time.

I have no formal training in physics though so take this with a block of salt.

>>9052850
Says who?

>>9053110
anyone who knows anything about the subject

>>9052908
Light isn't special because it has anything to do with observing surroundings. It moves at c because it's massless, and any other massless particle does the same. In fact you can take the Maxwell equations in the absence of charge and current and deduce that solutions propagate with speed c.

Newton's laws like Force = Mass * Acceleration aren't true, instead we find they're only an approximation that is true when travelling much slower than the speed of light. The true law predicts that as you get closer to C the force doesn't accelerate the object but instead adds more mass, this happens asymptotically so in the end you'd need to apply that force infinitely with infinite energy to accelerate up to C.
The laws also predicts that any/all mass less particles must travel at C, light being one of them, nothing actually that special about light only it is massless.

For the time travel bit Youtube light clock thought experiment

>>9052507
>Why can't you go faster than light speed?
Because every elementary particle is a weird twisted photon or series of photons with a specific geometry and energy. Because everything is made of light, it must move slower than light or rip itself apart.

>Why does going faster than light mean you're going back in time?
You can never go back in time. Not ever. Forget about time travel completely. Every bit of time travel fantasy is just that, unscrupulous physicists put negative signs in their equations to make idiots like you confused.

You can slow down time or let it run at "full speed" You run at maximum time if you have a local velocity of zero to the local cluster in an area that has the flattest gravity gradient (no massive objects like planets or stars).

>Dumb Dumb Version
>Everything is made of light, so you can't move faster than what you're made of.
>Time travel is fantasy, it isn't even worthy of science-fiction.

>>9052820
tachyons aren't real and every proposed tachyon has been a mirror of a real particle that "moves backward in time" which is why the entire thing is fucking stupid.

>if you moved an electron backwards through time
no, just no

>>9053589
>light clock thought experiment
This is where I start not following.
Light clock tick is from photons bouncing between mirrors on a 0<<v<c train and gives time dilation equation.
But if you made a sound clock and used echos you'd get the same time dilation equation for 0<v<vsound.
So why is it 'correct' to use light to measure time? Why believe in light derived time dilation and not sound derived?
>You can never go back in time. Not ever.
Not saying you can but I'm told going ftl would imply you did and I don't understand why that is true. Like if I went at 25,000c to the other side of the galaxy in 4 seconds then I could watch my photons arrive at my destination showing my trip in reverse but I'd still be 4s in the future.

File: 1474295295226.png (125KB, 850x850px) Image search: [Google]

125KB, 850x850px

>>9052820
>>9053482
>>9053589
>>9053689
What even is time? Why does time exist? What is it made of? I heard of retro-causality; if retro-causality is true, why can't we just travel back in time? If everything is made of light and light is massless, why do things have mass?

Simplest possible explanation.
Due to relativity as you approach the speed of light distances get shorter. When you hit the speed of light you are at all 3 dimensional points simultaneously and distance becomes a measure of time rather than physical 3 dimensional distance. For instance instead of traversing 3000 ly to get to a point in space you just arrive at the point 3000 years ahead of where you started.

>>9054401
Additionally all science fiction ftl drive is less about cheating to go faster than light and more about breaking relativity so it doesn't take you literally thousands of real years to get there.

so basically Spaceship Vs Lightbeam is the new version of Achilles Vs Turtle?

>>9054322
Time is just how fast a photon can bend between an electric and magnetic fields.

retro-causality is simply false. Consider Conway's Game of Life. It is a deterministic game with a grid of cells with rules for the life or death of cells. There are certain properties of the grid one is called Garden of Eden, this is a state that is unreachable from any previous state, meaning there is no way to create a grid of cells that will generate the Garden of Eden on the next turn.

Also there is ambiguity, if you have a state that can have multiple previous states, you have no way of knowing which was the actual previous state. If there are multiple plausible pasts you cannot know which past was the "actual" past.

Remember how faggots say information can be neither created nor destroyed? This is simply wrong, information can be weakened, blurred and lost to background noise. It happens all the time.

You cannot see a tree on Earth from light-years away. It doesn't matter how gigantic or precise your telescope is, you simply cannot see it. The information doesn't survive.

>>9053382
Which is not you

>>9054111
Sound is not the same as light. Sound requires a medium to travel through so there is a preferred frame. In other words, there's a difference between you moving towards the sound source and sound source moving towards you.

The ftl time travel thing is misunderstood. Being able to see light from the future is different than being able to kill your grandfather. Time travel to the past creates paradoxes. Ftl doesn't imply traveling to the past in any frame.

>>9055969
Aren't spacetime and/or EM fields the medium for light?
Or if you found a hypothetical mediumless ftl particle why shouldn't you use that instead of photons in your clock?
>Ftl doesn't imply traveling to the past in any frame.
Apparently some frames will see ftl going into the future as normal and some will see it going into the past.
Supposedly this is a huge problem because it means frames disagree about which happened first, departure or arrival, but departure must have happened first, therefore ftl is forbidden.
But I don't see why you can't solve the problem by having frames that see arrival before departure (like I would if I went to the other side of the galaxy in 4s) reinterpret it as a forwards time ftl event.
>>9053689
>run at maximum time if you have a local velocity of zero
Are motion in time and motion in space orthogonal?
You can remain stationary at maximum time rate of 1s per second.
If you start moving you'll do it at 0.9s per second.
If you go really fast it's at 0.1s per second.
Eventually you'll hit the speed limit c at 0s per second.
Why is the proportionality constant c?
When I ask "where does this c here come from" I get pointed to time dilation equations derived from light clock thought experiments. But that's not helpful, why a light clock and not a ftl clock?
>>9055969
>there is a preferred frame
I have a feeling the answer is something to do with preferred frames. Why do frames use c?

>>9055841
actually it is, but you can ask any other real scientist too

>>9056258
Cite?

>>9056972
google

>>9057097
Your job, not mine.

>>9057257
it's not my job, you are the one making the outlandish claim so you might as well study it a bit

>>9057462
No. You are wrong. Again.

>>9056258 made an assertion without backing it up. I asked him to back it up and got google as a reply.

I am not impressed.

So no, I never made any claims.

>>9057627
>hurr muh scifi particles are real I can't use google

>>9057779
>gurgle, I have lost it completely, trying to babble my way out
The movie.

>>9057805
it's okay kid, just run back to your mommy LOL

>>9056236
Light requires no medium. Fields are not mediums, they're just a measure of how much energy is in a volume of space.

As far as frames go, with light, there's no difference between you moving to something or something moving to you because light has no medium.

With sound you have air, or swimming you have water. The presence of these mediums means there is a measurable difference with you moving towards something or something moving towards you because you're either with the medium or against it. Examples being current in a river or wind blowing. Even without these, there's still a difference.

Consider ftl travel. If you travel fast enough, you could arrive somewhere before it was known you left. This seems like it would cause problems, but it really doesn't because you can't travel to a configuration of the universe that existed before you left. You could predict the future but you can't really say you're from the future. For that matter, if you travel to the future, you're not really traveling forwards in time because you're going to a future where you didn't exist if you hadn't. It works the same both ways.