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/sci/ - Science & Math

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4854122 No.4854122 [Reply] [Original]

Tell me in 30 words or less why I can't travel faster than light. Or 50, or whatever. But not a lot.

>> No.4854129

Time Dilation.

Boom. Did it in two.

>> No.4854130

As you go faster, more energy is required to propagate, as mass increases; as you near the speed of light, the relationship between energy needed and mass increase is an asymptote.

>> No.4854139

>>4854129
Okay, Mr. Fancy Pants. Why does time dilate?

>> No.4854140

>>4854130
>asymptote

you sir are a fucking moron

OP, it takes infinite mass to attain the speed of light, <span class="math">E = mc^2[/spoiler]

>> No.4854143

>>4854140

Put it into a graph. The result is an asymptotal relationship.

>> No.4854144

>>4854139
You asked me to tell you why you can't travel faster than light, not why time dilates. I'll need a bunch of fuckin' words for that.

>> No.4854151

>>4854143
no shit fuckhead, tell the OP where is the asymptote

is it at 1? Because mass can never be exactly 1 we can't go the speed of light

tell the OP where the fucking its asymptotic you moron

>> No.4854156

If there was a speed faster than the speed of light, light would go at that speed.

Does that work?

>> No.4854157

>>4854122
If shit like this could be explained meaningfully in 50 words or less it would only take a couple of days to understand every field of physics.

If you need everything spoonfed to you you in babby format because you're too fucking lazy to put in a little mental effort to understand something then you can go fuck yourself with the baseball bat your mother calls a dildo.

>> No.4854161

>>4854140

E=mc^2 doesn't imply that you can't go faster than the speed of light. ...at all.

Look at that equation and you'll realize there isn't even a term to account for velocity without subbing out the energy term, which defeats the whole purpose.

>> No.4854162

>>4854151

The equation is E=mc^2.

You need a value of mass to calculate the asymptote.

You are veritably an idiot.

>> No.4854170

>>4854162
so at any value of mass the equation is asymptotic?

kill yourself

>> No.4854176

>>4854170

>You need a value of mass to calculate the asymptote.

Read that again. Carefully. Then, take tenth grade math.

>> No.4854178

>>4854162

Try plotting a few points on your graphed equation. It's a first-order line.

You're the one that doesn't understand what the rest-mass energy equation does and does not say (as others have pointed out, you shouldn't be applying it to objects moving with any significant velocity), you shouldn't be calling people idiots. This is second-year physics stuff

>> No.4854181

>>4854178

By the way, I'm not the guy you're responding to. But him asking you to find an asymptote is a pretty solid objection, because there obviously isn't one

>> No.4854184

>>4854170
here is the time dilation formula... just end this thread now
<span class="math">
\gamma =\frac{1}{\sqrt{1-\frac{v^2}{c^2}}
<span class="math">[/spoiler][/spoiler]

>> No.4854185

>>4854176
Please go on, your confidence and ignorance are a delightful combination. Why does E=mc^2 imply an insurmountable constraint on velocity?

>> No.4854190

>>4854184
dammit all
\gamma = \frac{1}{\sqrt{1-\frac{v^2}{c^2}}}

>> No.4854194

>>4854184
That doesn't forbid passing the speed of light, it just gives a weird result. Keep googling and trying, this is amusing

>> No.4854198

>>4854190
anal rape yourself

<span class="math">\gamma = \frac{1}{\sqrt{1-\frac{v^2}{c^2}}}[/spoiler]

>> No.4854201

>>4854184
That doesn't explain why objects can't exceed c

>> No.4854204

>>4854198
There is a very easy and obvious formula that you would have encountered early on in any physics program that answers OP's question and this is not it, you're clearly some popsci fan who's far too smug for his own good. I'm seconding the "kill yourself"

>> No.4854215

The Energy produced from an object of mass > 0 is basically too high for the electromagnetic field to sustain itself, the speed of transactions between electrons have an upper limit, and it must be less than the speed of light or there could never be any "distinction" between electrons

<span class="math">3 \times 10^8 m \/ s^2 \times mass[/spoiler]

its just too big of a fucking number basically

>> No.4854216

But doesnt maxwell equations only prove that it is impossible to travel at the speed of light? If you travel faster than light you are supposed to to suffer the reverse effects of speeding up.

you can travel faster than light if you manage to find a particle that can repel gravity. create a worm hole, throw gravity-repeling particles inside before supergravity crushes the worm hole, enter it and exit in another place.

>> No.4854222
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4854222

>>4854216

>find a particle that can repel gravity. create a worm hole, throw gravity-repeling particles inside before supergravity crushes the worm hole, enter it and exit in another place.

>> No.4854241

Special relativity.

>> No.4854285

I was waiting to see if the popsci E=mc^2 guy would keep blustering, but I think he's done.

OP, the simplest example of this is to look at a formula for relativistic mass, say

Mrel= m0/(sqrt(1-(V^2/c^2))

That's ugly and I don't know how to use LaTEX because I'm a lazy fucker, but the basic observation is that the relativistic mass is given by the rest mass over a 1-(v/c) term. at v=c this means you have the rest mass divided by zero, which means you have infinite relativistic mass. We consider this to be impossible in the universe for fairly well justified reasons.

So you can't go faster than the speed of light because right now you're going slower than it, and to go faster than the speed of light you'd have to at some point reach the speed of light, which is impossible.

This does allow for things to go faster than the speed of light if they've always gone that fast, but you're not one of those things so I'll assume you're not concerned with it.

Does that make sense?

>> No.4854291

It's a violation of conservation of energy because only a finite amount of rest mass energy can be converted into kinetic energy.

>> No.4854298

Lorentz contraction formula

also this fag is a pretentious douchebag >>4854285

>> No.4854309

>>4854285
Im not op, but what about what this guy said:
>>4854216
Is it possible to move faster than light by moving through a place where the time is frozen?
There was a theory too about making a infinite string that by having infinite mass would make a blind spot that time is zero, so if you start moving said string it would make an undetermined space to move "backwards" in time.

i would like some answers from you too:
>>4854298

and anyone who wants to answer is welcome, since I want the most possible point of views, since this is an unobserved event.

>> No.4854315

with all these new physics anything is possibru

>> No.4854318

>>4854298
Wait how am I being a "pretentious douchebag?" It seemed like the most straight-forward explanation.

>> No.4854328

If you travel at the speed v > c, then in the rest frame of someone traveling in the same direction at a speed between <span class="math">c^2/v[/spoiler] and c, you arrive at your destination before you departed. And travel to the past leads to paradoxes.

>> No.4854334

>>4854328
not if you consider a multiverse a changeable timeline.

>> No.4854335

>>4854334
*or

>> No.4854354

>>4854328
That by itself wouldn't be reason to discount it. >>4854285
has it right

>> No.4854360

>>4854334
Admittedly, paradoxes aren't a very strong argument, since there are ways to have time travel without paradoxes -- multiverses (and changeable timelines are the same thing) being one of the most awkward and ad hoc ones, very suitable for Hollywood. But physics as we know it doesn't allow sending a chosen signal to the past.

>> No.4854370

>>4854360
Why do you think that physics "doesn't allow sending a chosen signal to the past?"

>> No.4854374

Just gotta say... OP's pic looks like the most fucked up family EVER.

>> No.4854383

>>4854360
Closed-timelike curves is code for "time travel" in relativistic physics, where they're not just allowed- they often show up in solutions.

Also, the only mathematical treatment of time-travel that I'm aware of is the Self-Consistency theorem, which explicitly states that backwards time-travel causes no problems with causality.

>> No.4854386

>>4854360
Sorry, the name changeable timeline sounded misleading, I was talking about TRaveling to the past would remake the actual timeline you are on because you added mass and energy to the equation. So you won't need to time travel again since yourself has already materialized in the past.

>> No.4854390

>>4854370
Universes without a strict one-way flow of causality might be too chaotic for life to develop.

>> No.4854401

>>4854370
You realize I am referring to current theories, right? Physics "as we know it."

>> No.4854410
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4854410

OP, as far as I can tell everyone in this thread has cited equations and said "this is true, therefore you can't go faster than light." I'd imagine that's not quite what you're looking for.

In the geometry that space and time have, the idea of "going faster than light" makes as much sense as "being closer than 0 feet". Intuitively, we expect there to be speeds faster than c, but it's just as wrong as assuming that you can keep heading in one direction and always end up closer to someplace.

>> No.4854409

>>4854122
Because your speed through space and your speed through time is a constant.

>> No.4854438

>>4854401
Right, I did understand that. I'm still not seeing what it is about "physics as we know it" that you think forbids time travel.
>>4854390
That's not really an answer, nor is it logical. If time travel were not forbidden, as it appears to not be right now, then clearly it wouldn't impede the development of life. Also, the self-consistency theorem handles the significant problems anyway.

>> No.4854445

wow you people of /sci/ are the most pretentious idiots on all of 4chan

>> No.4854450

>>4854360
You're clearly just a popsci kid, nothing we know about the universe forbids time travel. Concerns about paradoxes are the product of short-thinking, problematic events in the past have already happened in the present containing the time machine.

>> No.4854455

>>4854445
calling people pretentious simply because they have a better understanding of the subject at hand than you isn't a very good way to go through life. I'm assuming that you're used to being able to assert to other uneducated people things you half-remember from a Discovery Channel documentary, that's not going to work on a board specifically tailored to people educated beyond that.

tl;dr- it's not us, it's you.

>> No.4854459

>>4854445
again, how am I being pretentious? I'm seriously asking you, I've been trying to just be concise and clear

>> No.4854471

Because you have mass.

>> No.4854476

>>4854471

Also, even if you removed mass, you would (maybe?) only be able to travel as fast as light, not faster.

That said, if Black Holes exert enough power that light can't escape, perhaps you could build some form of "Black Hole Sail" that drags your ship towards it at a faster than light speed?

>> No.4854487

>>4854476
how do you make the black hole move faster than light?

>> No.4854488

>>4854438
Quantum mechanics and general relativity start from a state in the past and use it to predict the future. You could try to turn it around and predict the past from the future, but the most economical explanation for the arrow of time is that the universe started out from some particular state whereas the ultimate fate of the universe is subject to QM's randomness.

>> No.4854494

>>4854476

Sounds similar to the Alcubierre drive.

>> No.4854498

>>4854487

You wouldn't. You would have to find a way to continually create a series of black holes in front of your vehicle.

Sort of like throwing out a grappling hook, pulling yourself forward the length of the rope, and tossing it out again.

>> No.4854609

>>4854488
What? All of general relativity is time-symmetric, I don't want to speak authoritatively about quantum mechanics but if you have an example of a principle or law that doesn't exhibit time-symmetry I'd love to see it- be specific, don't just throw out a random phrase you found on wikipedia.

Also, having an arrow of time doesn't forbid time-travel in the slightest. That's a very strange non-sequitur

>> No.4854646

>>4854445
anyway, moving on.

>> No.4854711

>>4854488
>popsci gibberish

>> No.4854743

>>4854122

Because people smarter than you say so

/thread

>> No.4854747

>>4854743
I'm hoping it will soon be /summer

>> No.4854837

Because time is weird compared to other space dimensions. Imagine you move 3 meters in one space direction and 4 meters in another. Pythagorean theorem, you move 5 total meters. But with space and time, it's (distance in space)²-(distance in time)²= total time elapsed. This is called a Minkowski metric. If you use the proper units- seconds for time, light-seconds for distance- you find out that if you try to go somewhere faster than light would get there, you get imaginary numbers. This is equivalent to the universe saying "Fuck you, you can't do that"

>> No.4854855

Aw goddamnit, error correction. It's called /Lorentzian/ geometry (how did I fuck that up?) and it's distance in time squared minus distance in space squared, not the other way around.

>> No.4854864

>>4854140
>>4854140
>>4854140
>>4854140

E=mc2
E=mc2
E=mc2
E=mc2


hurr durr implying that this equation is not flawed in anyway whatsoever

>> No.4856524

>>4854837
No it isn't, solutions involving imaginary numbers are abundant in physics.

>> No.4856529

>>4854837
That's not true
>>4856524
has it right, but it's deeper than that. The Minkowski spasce was derived FROM imaginary solutions in relativistic physics, so to try to claim that we would need to discard imaginary solutions from a glorified complex plane is a little rich.

>> No.4856618

because you need infinite energy to attain the speed of light

>> No.4856698

>>4854122
General relativity says you can't.

>> No.4856760

>>4854139
>>4854144
We don't know. It does. We know this because the evidence says so.

See:
Feynman 'Fun to Imagine' 4: Magnets (and 'Why?' questions...)
http://www.youtube.com/watch?v=wMFPe-DwULM
for Feynman answering almost exactly the same question.

>> No.4856842

what if i could run, and keep increasing my speed...as i near the speed of light, would i slowly stop moving as fast and just not go faster? or would i pass it

>> No.4858279
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4858279

>> No.4858319

>>4856698
Special relativity, actually. EFEs can be written and solved without any Lorentz transformations, it's a common misconception that GR was built to handle accelerating frames.

>>4856760
>We know this because the evidence says so.
Special relativity is a set of symmetries that are part of SO(3,1), which is a subgroup of a larger Lie group that encompasses all of the laws of physics. These symmetries are attached to every point of space-time and determine how particles or strings (geometric information) interact and transform for space/time/null-like intervals.

>>4854144
>>4854139
See Taylor, Wheeler - Spacetime Physics

>> No.4858323

you possess mass. That's only three words. /thread