/sci/ - Science & Math

>we
>they
>he

Who?

>>6284562
Research on the Internet

I just want clarifications about the universe's "speed limit"

>>6284559
you got it wrong, you need an infinite amount of energy to accelerate UP TO the speed of light.

I don't know where you got this "faster than" from.

Because the closer you are to the speed of light, the higher your inertial energy. Thus the energy you need to go a bit faster increases with your actual speed. To get to the speed of light you would need infinite energy, and thus it is impossible (if you have mass) go go that fast.

>>6284564
>To get to the speed of light you would need infinite energy, and thus it is impossible (if you have mass) go go that fast.

What about light that is traveling on the speed of light? I mean they don't need infinite energy?

>>6284568
Short explanation: photons dont have mass

>>6284574
Oh... Know I kind of get it.
Now why don't photons exceed the speed of light? I mean why can't they travel faster? Why do they follow the speed of light?

>>6284582

speed tickets.

>>6284582
Short explanation is: if you start from Maxwell's equations for ED, you get that the speed of propagation of an EM-wave (read: light) in a vacuum is a constant, usually denoted by c, which is independent from the reference system (this is also one of the basic assumptions of SR). This fact has also been confirmed experimentally.

A lot of these questions tend to come up based on the assumption that the speed of light is some kind of technicality instead of a fundamental property of the universe.

I'm not a physicist but someone on /sci/ explained the speed of light as being the speed at which information in the universe updates itself more than what just happens to be the speed of a photon. This explanation made a lot more sense to me.

>>6284670
Pretty good understanding, you can also see it pretty easy using basic maths.

Under Maxwell's equations, the universal speed limit is a function of two constants - the permeability and permittivity of free space. You can think of these as how well vacuum space is able to conduct magnetic fields and electric fields, respectively.

As to OP, if you want a mathematical explanation why "we" can't get to the speed of light (or exceed it), you can get there very simply using Einstein's famous EQ. This applies to anything with non-zero rest mass.
You find that as you add more and more energy, your velocity will increase, just as you would expect. However, near the speed of light the return on velocity gained per unit energy added becomes asymptotic. This is because of mass-energy equivalence. You are literally increasing the mass of the object you are trying to accelerate as you push its velocity closer to light speed.
Each fraction of a percent gained in velocity becomes exponentially more expensive in energy, approaching infinity.
To exceed the speed of light, you would then need more than infinite energy (using our simplified model). This is of course more than all the energy in the universe.

However, this limit is imposed on motion through space. So distant galaxies can actually recede from us faster than the speed of light, not because of their own intrinsic speed, but because of the expansion of space itself. The expansion rate of space does not to my knowledge have a limit. The constraints are simply based on the relative densities of dark energy and matter, in conjunction with the scale factor of the universe... hooray physics!

>>6284559
String theory and OP.jpeg will help me answer
>Why can't we go faster than the speed of light
If you will, look at OP.jpeg and see how the light looks as though it is taking the form of strands. This is the perception that the faster you are moving, the more you see linear order with the particles of light around you, the truth behind not being able to go faster than the speed of light is very basic.
It's not that you cannot travel faster, it's that if you were to go faster than the speed of light, your basis and concept of "moving," becomes null. With nothing as your only source of interpretation of travel, you could not know whether you were moving at all. The Universal speed limit is just that, a limit. Limits can always be surpassed.

If you are moving faster than the speed of light, you are no longer technically "traveling." This is not to say that if you were to accelerate past the speed of light, then somehow return to it you would not have covered more of something, possibly time-space or spacetime. Honestly, going faster than the speed of light is as definitive as dividing by zero at this point. It's not impossible, it's just impractical.

Trying to go faster than the speed of light is already done by technology today by using routing based order. Meaning, re-directions can cause something to use systematic approaches to send information in multiple directions and flows to cover more distance.

The idea of moving something, faster in a single linear direction than the speed of light is futile, and impractical. There are better ways to get something from A to B than traveling the distance.

Black Holes can warp space & time. Evidence for this remains uncertain as if you look at optical illusions such as mypost.jpeg you will see that distance can be covered without movement. Space and distance can be covered with little to no movement at all. Static things can remain unchanged, yet no finite definable form.

>>6284885
saved for fut ore use.

>>6284564
Anyone ever play the original Zork? Remember the bridge?
>You're halfway across the bridge.
>You're three quarters of the way across the bridge
>You're seven eighths of the way across the bridge
>You're 15 16ths of the way across
>You're 31 32nds of the way across
>You're 63 64ths of the way across
>...
>You're infinitely close to the end of the bridge
>You're infinitely close to the end of the bridge
>You're infinitely close to the end of the bridge
It works like that. You can't actually ever get across the bridge, you can only get *close* to to crossing the bridge.

>>6284914
>Zeno's paradox on zork
I don't remember that.

>>6284868
>As to OP, if you want a mathematical explanation why "we" can't get to the speed of light (or exceed it), you can get there very simply using Einstein's famous EQ. This applies to anything with non-zero rest mass.

OP here again. Can you show even a simple computation of that. I'm not really good at math and science. I'm just curious about answering and knowing some of the questions about the universe.
Like is it really infinity if you propel an object to the speed of light?

>>6285006
I'm not that guy but he seriously explained it to you in the simplest way possible. It doesn't really get less mathematical than that.

>>6284914

That was from Beyond Zork, pleb.

>>6284559
It's a first principle. A basis in which you build from and which predictions match very well with observed phenomenon. You cannot explain why we can't go faster than the speed of light within the framework of relativity.

>>6284559
Because at higher velocities you have greater relativistic mass.Therefore more force is needed to accelerate.Repeat ad infinitum .

how do we know that all objects in the universe are not already moving at the speed of light?

>>6285216
what if light doeskin move and we are all moving at the speed of light?

Why can't you become light and go faster?

how do we know the speed of light is constant?

they change the value every few years, maybe it fluctuates

if adding energy to an object to increase speed also increases mass of the object, what would happen if there is a way to reduce mass of the object as you add more energy

what would happen if you blocked the higgs field?

Why do you want to go faster than the speed of light? If you get close enough to it, length contraction will mean that wherever you wanted to go is already nearby.

For example, let's say you want to go to a star that is 100 light years away. Get in your ship, aim at the star, and accelerate up to 99.99999999% of the speed of light. Now your star is about half a day away! Enjoy your in-flight movie, take a nap, and you're there!!

>>6285604
>object is 100 light years away = light itself takes 100 years to get there
>travel slower than light at 99.9999999% the speed of it
>reach it faster than light itself

wat

>>6286329
The "event" (you stepping on/off the spaceship) happens at the point in same space for you, (spaceship door) thus you have proper time and every other reference frame sees the two events taking longer to happen than you will. It will still take a little over 100 years in planet time, but *you* will only experience 100/gamma years. It's not correct to say you reach there faster than light, it's a matter of reference. The light experiences no time passing (so you will still take longer if we consider traveling frames) as we are reminded in the hover-text of http://xkcd.com/811/

>>6286329
It's called the magic of acceleration, my friend. If you're not in an inertial frame, a lot of interesting things can happen.

http://en.wikipedia.org/wiki/Twin_paradox

>>6286382
>>6286387
That's fucking retarded. Why is the universe like this?

>>6286392
Why? Because it's awesome!

The craziest part is all of this is true, or at least has not yet been shown to be wrong, and not just some purely theoretical thought experiments. This experiment in the 70s took atomic clocks and showed that they DID tick slower (experience shorter time) than a clock on the planet : http://en.wikipedia.org/wiki/Hafele-Keating_experiment .

Not fucking retarded, it's fucking Einstein!

>>6286392
I don't think the previous answers explained this correctly.

What Einstein and Lorentz and a bajillion physicists proved was:

1) There is no absolute frame of reference in the universe.

2) In ANY frame of reference the maximum speed is the speed of light.

You can never approach the speed of light in your own reference. When someone says "If I just use rockets just under the speed of light - wouldn't I be going faster?", they are applying 2) without applying 1).

Basically, in your own frame of reference, no matter how fast you are going in ANOTHER frame of reference, the speed of light is C (which in earth's frame of reference, C is approx 3*10^8 m/s). In other frame of references, as you move closer and closer to the speed of light, you will start to stretch in the direction of your travel. In your frame of reference, as you accelerate, everything moving slower than you CONTRACTS as space contracts - Your acceleration compresses space and causes you to age slower relative to other slower frames of reference.

Anyways, when someone says, X is 10 lightyears away, they mean, in earth's frame of reference, X would take 10 years to reach at the speed of light. However, as you accelerate, the space between you and X will shrink, so it no longer takes light 10 years to reach X. IN your own frame of reference, you could travel to X in 1 second. However, in earth's frame of reference, it will take you longer than 10 years to reach X.

Surpassing the speed of light means that you can reach X in less than 20 light years in earth's frame of reference. It also means you could communicate information back in time (reaching X before light means you see X in the past etc).

>>6286410
I need to correct a mistake:

You reach and return to X in less than 20 years, which means information (in light) leaving X would arrive after you

Assuming we could travel at the speed of light how long would it take to travel 10 light years away?

>>6286452
0

>>6286410
>>6286413
>You reach and return to X in less than 20 years, which means information (in light) leaving X would arrive after you
This is part is flat out wrong since the light would be travelling faster than you in any reference frame, hence you can't beat light from X to Earth that left at the same time as you.

>>6286467
wat

>>6286479
Oh, I misread that last part. Didn't notice that it was referring to literally travelling faster than light, rather than the effect of travelling faster than light in the moving reference frame compared to the Earth's reference frame.

>>6285272
you'd burst into treats.

Bumping great thread.

Bump?

>>6285604
I expected people to flame this comment of mine... instead I find out that /sci/ basically agrees. So /sci/ actually knows what it's talking about sometimes.

I'm both disappointed, and pleased.

>>6284586

because time would stop if you reach light speed. which is why they say photons are timeless, because they're always traveling at light speed