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/sci/ - Science & Math

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6835188 No.6835188 [Reply] [Original]

Does light have mass? And if not. why is it constrained to a certain speed?

>> No.6835195

>>6835188
No.
And I don't know but I believe it would having something to do with the physical properties of the fabric of space through which it travels.

>> No.6835199

Would the lack of a speed limit in the universe have any weird consequences?

>> No.6835201

>>6835188
Because the speed of light is what the fastest masses are traveling from the center of the Big Bang. You can't get enough energy to too the energy present in the Big Bang

Light is bent by gravity so it probably had mass

>> No.6835203

>>6835199
Mate, entropy is already complicated enough without your crazy hypotheticals.

>> No.6835205

>>6835201
>Light is bent by gravity so it probably had mass
Light itself is not bent by gravity.
The fabric of space on/through which it travels is.

>> No.6835206

>>6835205
Oh, that makes more sense.

>> No.6835211

>>6835201
>Light is bent by gravity so it probably had mass
You are getting fucking MIDDLE SCHOOL physics wrong. American middle school even. You are literally dumber than a 5th grader.

>> No.6835221

>>6835211
Thanks anon. Sorry I don't read enough pop science books.

>> No.6835229

>>6835221
You don't need pop science to know the answer to the question "if I drop a bowling ball and a baseball from the same height, which will hit the ground first?"

>> No.6835232

>>6835229
Depends on your perspective, anon.

I'm actually so invested in thinking about time and relativity that I didn't think about what light was. But yes, I understand Newtonian physics very well

Does acting like a cunt make you feel smart?

>> No.6835243

>>6835232
>Does acting like a cunt make you feel smart?
This.

Sooner or later you will realise that a lot of people in science have very large egos.

>> No.6835249

>>6835243
I already know. If you go on /lit/ there are still egos, but going from there to /sci/ is a trip. Everybody on /sci/ seems to think that having a rudimentary understanding of physics and math means you have license to treat people like shit.

It's kind of sad.

>> No.6835250

>>6835229
The baseball will hit the ground first.

>> No.6835251

>>6835249
Funny thing is they don't understand it. They rote learn it. Very few people understand it, like you would need to in order to seriously advance it for example.

>> No.6835259

>>6835249
Maybe if you retards tried to actually at the very least google this shit before coming here and asking the same questions again and again and again, then we'd be nicer about it.

Which is why we rather have that people here have at the very least a first year understanding on the damn subjects of the board.

>> No.6835270

>>6835259
I'm not even OP. I was the one who answered why the speed of light being a limit is a consequence of the energy present at the Big Bang. Then I said light has mass because my retarded mind went "dur, light bends in gravity, Gravity's acceleration operates on newtons law of gravitational pull" and filled in the units. I was corrected and politely admitted it.

Then that anon felt it was necessary to be a cunt. I don't understand what his problem was

Also, I do read on my own. I'm a lower division math major, but am teaching myself upper division material so I can supercede my peers. Physics is a hobby. I come on /sci/ to help expose my mind continually to new problems to keep it fresh. There's no room for faggy elitism in what I do.

So I don't get the random abuse. I just dont

>> No.6835276

>>6835270
>So I don't get the random abuse. I just dont
Its not anything complicated really. Just basic emotions and egotism.

>> No.6835295

>>6835276
Yeah, you're right.

>> No.6835307

>>6835270
Maybe after you're here for a while and see the same popsci questions being asked every day you'd see what I mean.

> I come on /sci/ to help expose my mind continually to new problems to keep it fresh. There's no room for faggy elitism in what I do
You came to the wrong forum, go to stackoverflow or mathoverflow (go there and you also see the difference in types of questions and why we don't like these types of questions).

>> No.6835319

Mass is a property particles not moving at the speed of light exhibit

>> No.6835323

>>6835270
It's because these threads are made all the goddamn time and eventually I'll blow up about it, sometimes on the wrong person.

There actually one time was a person who didn't know a bowling ball and base ball fall at the same speed.

>> No.6835332

>>6835323
Under the Newtonian interpretation of gravity, they do. Under relativity it would depend on your perspective and they still fall at different rates literally (by tiny amounts) due to wind resistances, natural differences in the earth's gravitational field (e.g., ocean level varies around the earth because gravity is not the same everywhere) or because of gravitational pull from the moon.

So it's genuinely not true that objects fall at the same rate. But for nearly all practical applications on earth, yes, the acceleration due to gravity is constant relative to mass.

Not exactly related but it's important to remember that "truth" in science isn't quite right. As far as I can tell, science always produces results that are never complete. Newtonian mechanics are a perfect example of science that is "true" in its application but false in others.

But yeah, I agree. If someone wants to be learned, they have to stop relying on other people. You have to be able to study independently, or you can't be a truly important intellectual

>> No.6835337

>>6835307
Thanks for the reference. I used to go to stackoverflow when I thought I wanted to be a comp sci major (until I saw the types of people that get those degrees and what you actually study in those programs). I'll check them for science and math questions now

>> No.6835341

>>6835337
Actually I confused stackoverflow there.

I mean math.stackexchange and mathoverflow.

There's also physicsforums.

>> No.6835368

>>6835250
Actually the bowling ball is denser, so it's mass per wetted area will be larger and the drag will be less.

>> No.6835378

>>6835249
>>6835243

/sci/ can be pretty rude, but on the other hand there are a lot of trolls here. A sincere quest for self improvement is usually well-received here tho.

>> No.6835380

>>6835368
The acceleration due to drag is proportional to A / m, not density by itself.

>> No.6835390

>>6835380
I know, that's what I said.

Larger density + larger size = more mass than a baseball

>> No.6835392

>>6835390
Which results in greater drag, not less.

>> No.6835399

>>6835332
>>6835368
But wouldn't the bowlingball attract the earth way more than the baseball (setting everything but gravity aside) and thus those two would colide faster?

>> No.6835418

>>6835392
I misspoke, for drag yes, but I meant terminal velocity, which is greater for the bowling ball. Therefore the bowling ball will hit first.

>>6835399
>But wouldn't the bowlingball attract the earth way more than the baseball
Yes, the FORCE on the bowling ball will be greater, but not the ACCELERATION. Acceleration is the only thing that determines how fast something will fall. With drag then mass starts to matter, but the acceleration from gravity will always be the same.

>> No.6835428

Light has mass. It doesn't have a rest mass because it doesn't exist at rest.

Why does it move at c? There's no answer.

>> No.6835432

>>6835428
No it doesn't. There is no other mass than rest mass. And please never spread the antiquated bullshit about relativistic mass again.

>> No.6835437

>>6835428
>Why does it move at c? There's no answer.
Yes there is. The answer is that light has no mass and therefore must always travel at the speed of light.

>> No.6835445

>>6835418
Yeah, I fucked up, the bowling ball will hit first.

>> No.6835450

>>6835432
>I don't like it so it isn't real
Sorry, science doesn't work that way.

The concept of rest mass does not apply to photons as they cannot be stopped, they do however have an effective mass, hf/c^2.

>> No.6835453

knowing the proper definition of mass and even moment of inertia should be enough to answer your question OP

>> No.6835458

>>6835437
that doesn't explain why light has that speed

>> No.6835467

I use to think the speed limit existed because it's needed for a particle to derive a velocity based from its energy, but that's apparently wrong.

>> No.6835468

>>6835450
Photons have mass 0. Effective mass is not mass.

>> No.6835469

>>6835458
Yes it does, c is a fundamental constant of the universe.

>> No.6835474

>>6835469
one, no it doesn't, why 300mil m/s, why not 500 or 10?
two, c is a derived constant from mu0 and ep0 which are actual fundamental constants

>> No.6835489

>>6835474
one, c is actually 1 planck length/ 1 planck second
two, historically yes but c is found to be a much stronger fundamental quantity than the permeability and the permittivity

>> No.6835492

>>6835188
Mass no, pressure and momentum yes.

>> No.6835495

>>6835489
planck units have absolute no application and are merely ways of writing units in terms of base constants, and they are defined as including length/time as c

>> No.6835497

>>6835341
Thank you.

>> No.6835502

>>6835458
It has that speed cause that's the fastest it can go in are space/time.

>> No.6835507

>>6835270
>energy present at the big bang

it was infinite, universe is infinite

>> No.6835512

>>6835507
>it was infinite, universe is infinite
Sure it is, m8.

>> No.6835515

>>6835507
Yes, but the energy contained in observable mass is finite. The fastest moving mass we can see is traveling at c relative to us. There is no point of observation where you can witness any mass above c. This is why it's a fundamental constant of the universe

>> No.6835592

>>6835515
In case you're wondering why, energy is a relativistic concept. If the maximum speed is c, then that means that there is a maximum kinetic energy. In order to accelerate beyond c, you have to input more energy than actually exists in every reference frame in the universe.

Photons can do whatever the hell they want though.

>> No.6835595

>>6835592
>energy is a relativistic concept
Good god, just stop it already.

>> No.6835604

>>6835595
Can you explain what's wrong about what I just said?

>> No.6835605 [DELETED] 

>>6835399
>>6835399
Yes. The bowling ball will hit first if you consider only gravity (considering not constant gravity).

>> No.6835608

>>6835418
>>6835399
Yes. The bowling ball will hit first if you consider only gravity (considering not constant gravity).

>> No.6835614

>>6835604
>Energy is a relativistic concept
While energy is dependant on the frame of reference, energy is not a "relativistic concept" (whatever you exactly mean by that)
>If the maximum speed is c, then that means that there is a maximum kinetic energy.
No, just no. You can put as much energy as you like into a particle without it ever reaching c.
>In order to accelerate beyond c, you have to input more energy than actually exists in every reference frame in the universe.
No. It's simply not possible to accelerate beyond c. Even with infinite energy it's not possible.

>> No.6835636

>>6835614
>While energy is dependant on the frame of reference, energy is not a "relativistic concept" (whatever you exactly mean by that)
He probably meant just that

>> No.6835645

>>6835614
>>6835614
I don't mean absolute energy, I mean kinetic energy. The kinetic energy of any mass is relative to the reference frame.

>you can put as much energy into a particle that you like without it reaching c

How do we know this? If kinetic energy is equivalent to 1/2 mv^2, and if the fastest masses are moving at v=c, then in order for any mass to go past the speed of light, wouldn't it's kinetic energy have to exceed the relative kinetic energy possible at that location?

In other words, there is no such thing as infinite kinetic energy, it's just impossible to put in more kinetic energy than exists

How is it not possible to accelerate past c with infinite energy?

>> No.6835652

>>6835645
Infinite energy meaning more kinetic energy than exists in all reference frames

And I didn't even consider potential energy, but wouldn't potential energy also depend on the frame of reference?

>> No.6835663 [DELETED] 

>>6835608
Or not, never mind.

>> No.6835703

jacob barnette here
as you break the speed of light, any interaction between you and everything else will cease as there's not enough time. it follows then that, due to quantum tunneling, you will never be able to fully escape the universe as there's a probability i for interaction which approaches 1 as you approach infinite velocity. the math here should be pretty obvious.
the absence of a speed limit is a reflection of a reality with the distinction that the previously mentioned mechanic does not occur. the difficulty then becomes identifying if we live in a universe which is subject to a speed limit or if we live in a universe which is not subject to a speed limit.
we consider particle x which is traveling at a velocity close to c. we observe that the translation of energy to velocity is not a linear function and that it behaves rather asymptotically. traditionally, this behavior is explained by einstein as c being the universal speed limit. if we consider quantum tunneling however, it becomes clear that this is simply a matter of quantum tunneling. namely, the probability isubx, which denotes the chance for particle x to be missed by the energy approaches 1 as x approaches c.
thus, we have proven that there exists no universal speed limit.

this book i'm reading said that, when you write a proof, you should leave out all the obvious math. sorry if you don't understand it.

jacob barnett is not in the building anymore

>> No.6835708
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6835708

>>6835703
>mfw

>> No.6835727

>>6835703
I want to beliebe

>> No.6835734

>>6835703
>not enough time

Meaning that changes in position relative to others simply doesn't apply? As that's what time is

>> No.6835748

>>6835428
But they've stopped light in the lab

>> No.6835757

>>6835748
Black holes stop light every day

>> No.6835776
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6835776

>>6835437

No, light moves at the speed of light because it's almost the speed of time, since when something tends to reach the speed of light, the time of this thing tends to zero (but will never be zero), considering that, we can say light travels at a speed slightly slower than the speed of time (the zero time point), that's why we say this is the maximum speed alowed by nature.

Does light have mass? Well today we know that some kind of energies doesn't interact with the Boson Higgs, making then "massless", light has energy, but doesn't interact with it, so no mass for light.

>> No.6835788

If a particle was traveling faster than the speed of light and was emitting photons but didn't interact with those photons, then if it passed through an observer that observe would witness the particle's emitted photons in reverse time

What if the universe is composed entirely of such particles?

>> No.6835802

>>6835497
No problem.

Check out physics.stackexchange too, which I forgot to mention.

>> No.6835820

>>6835788

Wut?

Mind explaining that?

>> No.6835827

>>6835206
kek

>> No.6835871

>>6835188
Yes, it has relative mass
/thread

>> No.6835906
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6835906

>>6835734
jacob bernette here again to educate you fools

consider this thought experiment.

imagine taking a handgun and firing a single bullet at a wall once every second or so. now we call the shortest distance between the barrel of your gun and the wall D and the line then along which your bullets will travel is denoted GUND. now, we denote the point at the center of GUND to be F. now we position a person PERSON so that the line PERSONF is perpendicular to line GUND. PERSON shall now attempt to accelerate along PERSONF, we prove the following theorem.

the probability of PERSON colliding with the SHOTS FIRED by your gun DECREASES as the velocity of PERSON traveling along PERSONF INCREASES.
to prove this, we apply simple logic. if person moves at the pace of a snake, he will be in the line of fire for more than a second and is therefore guaranteed to be hit. if person moves at the pace of a car, he is unlikely to be hit. if person moves at the speed of light, he is even less likely to be hit.

theorem proven. now follows the greatest moment of your life.

think in quantized terms.

if you scale everything down to planck lengths then by nature, the chance of collision approaches zero as is because there exists but a single infinitely small unit of time which leads to collision. this infinitely small unit of time never goes away though, it just becomes shorter and shorter and shorter as your velocity increases. some boring math then yields an example probability of collision if PERSON moves at walking pace to be around ~5*10^-41.

we then wonder what happens if there is such a thing as a smallest possible unit of time and in doing so, accidentally give birth to quantum physics. whoops


jacob now takes his leave, goodbye.

>> No.6836081

>>6835906
That's what you get when women smoke during pregnancy.

>> No.6836158

>Does light have mass?
/sci/ is so smart with these topics everyday

>> No.6836159

>>6835645
>If kinetic energy is equivalent to 1/2 mv^2
It's not. The rest you said is basically just incoherent rubbish mixing up concepts from classical mechanics and SR.

>> No.6837674
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6837674

>>6835203

>> No.6837706

>>6835188
Light has energy based mass because it has energy. Is there something special about energy based mass that allows photons to move at light speed despite having mass?

>> No.6837722

>>6837706
There is a term called "relativistic mass" which has fallen out of favor. It is the same as total energy. The SAME. Now, we use the term "mass" to mean "rest mass" or "rest energy" (the total energy an object with zero momentum would have). So, light has energy. light has relativistic mass ("archaic" term). Light has no mass. Light has no rest mass. Light has no rest energy. These are all true statements.

all objects with zero rest mass travel at the speed of light * in addition to these objects' ability to carry energy.

* vacuum, etc etc

>> No.6837765

>>6835188
Photons do not have rest mass.
They have energy.
Mass, ass in, if you set one on a scale (while it's moving), it has no measurable mass.
If you put a "scale" in front of one, and let it run into the scale, then it has "mass".
It's like this: Photons stand still in time. Time does not flow for photons.
When a photon is spawned, from the point of view of that photon, it instantly arrives at it's destination. That star you're looking at, a hundred light years away? If you were that photon, you would experience no time passing from when you came to be, until you fell into that human's eye.

>> No.6837774

When you point your 5mw 445nm laser pointer at the wall across the room, from your reference frame, it took a certain very small amount of time for those photons to travel that distance.
From the photon's point of view, it did not travel any distance. It came to be, and at the same exact instant, it was impacting the target.
From the local reference of the photon itself, two places are the same place.

>> No.6837777 [DELETED] 

>>6837765
shut the FUCK up nerd LOL

>> No.6837791

>>6837777
What, you though photosynthesis was strait forward and simple?
In plant cells, a photon travels all possible paths in, and the plant "chooses" retroactively, the best path.
This is only possible if photons stand still in time.
If time flowed for photons, then a single photon could not travel all possible routes into the cell at once. It would travel one route, time would pass, etc.
But because the photon does NOT move through time, it can travel a near infinite amount of routes, all at the same time.
Then of course from this point, it's child's play for the cell to cause a collapse that results in the light wave collapsing into the most efficient particle path.
There's really nothing else it can do at that point. When the collapse happens, the plant has already "used" the photon. After all, this universe strives to be self-consistent.
It could not be self-consistent if extra energy was extracted from a photon, energy that "doesn't exist".
This breaks continuity.

>> No.6837801

Also, it's not just plants.
Your own cells do this very thing when you go tanning, and they make vitamin D.
We are used to seeing ourselves as organisms that do not utilize photosynthesis, but this is wrong.
We in fact rely on photosynthesis to survive.
Our cells work in a very similar manner.
Food for thought...
Our cells are capable of absorbing a GREAT many frequencies of light.
;^)

>> No.6837819

tl;dr, if quantum mechanics was wrong, no life would exist.

>> No.6837828
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6837828

If you want to see how deep this rabbit hole goes...
Set up an experiment where in a dark an secluded place, you can see your own reflection in a mirror, reflected from another mirror.
Two mirrors between you and your image.
There's a whole world there you haven't seen.
>https://www.youtube.com/watch?v=0FyLcHxbSRk

>> No.6837883

>>6835205
E=mc^2
Light is energy that can be measured in joules. It is a subatomic particle, though much smaller than neutrons, electrons, etc, theoretically it does have mass.

>> No.6837997

>>6837883
It's the 6th line in the info box. Retard.
http://en.wikipedia.org/wiki/Photon

>> No.6838003

>>6835368
you're assuming that the distance from the earth to the bowling ball is the same as the baseball and that this could happen. one will strike in a time increment different than the other even if it a very small increment.

>> No.6838006

>>6835495
you seem the smartest. go on...

>> No.6838062

>>6837765
why ?

> you would experience no time passing from when you came to be, until you fell into that human's eye.

>> No.6838065

>>6838062
http://youtu.be/GpgGJaQfrgE?t=16m20s

>> No.6838101
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6838101

The question as to Is the speed of light the ultimate speed limit can not currently be answered because we are simply unable to observe any thing significantly faster. There have been a few experiments that have indicated speeds just above C are possible. And yes light is a particle and thus has mass ; light can impart kinetic energy which is impossible without mass

>> No.6838106

>>6838101
You really should learn the difference between momentum and mass.
Your texts are embarrassing to read.

>> No.6838110

>>6835199
The vast majority of special relativity relies on c, so yes.

>> No.6838127

>>6835188
It's heavy.

>> No.6838154

>>6835437
>light has no mass and therefore must always travel at the speed of light.
How come light travel slower in Water or Glass?

>> No.6838169

>>6838154
Because the photon reacts with the electrons around it, and the progression is of a group of particles, or the attributes of them.
https://www.youtube.com/watch?v=CiHN0ZWE5bk

>> No.6838191

>>6838169
A way of thinking about it is that the photon creates a bubble of excited stuff around it, and then this excitation bubble moves along with it, moving slower than c. The bubble is called a parton.