B Light & Space: Investigating the Unknown

[john-of-the-divine]

There's some serious good news here: Thanks to the internet you don't have to go to a ridiculously expensive top-flight school to learn this stuff. Textbooks and lecturers' notes from very strong academic programs are available online; for example, Sean Carroll and Gerard t'Hooft have both placed first-rate general relativity textbooks on the web, and there are many more good online resources.

On the other hand, you do have to work at it. Plan on spending several years of the same sort of effort that you'd put into learning something else worthwhile, and resist the impulse to skip learning the math that's needed to deal with all of physics since Newton (who more than three hundred years ago invented calculus because he needed it to solve the open physics problems of his era). Nonetheless... A few years of concentrated effort will give what some of the smartest people who ever lived spent centuries developing... That's good news.

I've gotten most of my knowledge from science, discovery, ext. can see and I understand the theories, until I asked the great "what if" question. now I want to know what "it" is that mass effects to make gravity. guess I need to understand the math

 

[Dale]

I understand the theories

if that were true then you wouldn't be asking about fabric and aether. Pop sci sources are entertainment, not education. They make you feel good, but they don't teach you the theory.

It is good that they motivated you to ask more, but you need to recognize that if you are interested in the answers then you are going to have to unlearn a bunch of pop-sci baggage

I want to know what "it" is that mass effects to make gravity.

"It" is the geometry of physics

 

[Nugatory]

no, I haven't. how reliable is Wikipedia?

As @berkeman says, wikipedia is generally OK for well-understood stuff that's not near the cutting edge. A pretty good rule of thumb is that wikipedia coverage at the undergraduate level in math and science (but emphatically not the social sciences!) is probably reasonably good. Anything beyond that... Not so much. It is prudent to read the "Talk" section of any wikipedia article before you decide how trustworthy it is.

The Physics Forums policy is that wikipedia is not in general an acceptable source, but we routinely allow and provide links to wikipedia articles that the mentors have found to be good.

 

[john-of-the-divine]

The Michelson Morley experiment ruled out a rigid aether and ring interferometer experiments ruled out a dragged aether. The only aether that remains compatible with experiments is experimentally indistinguishable from no aether.

that's why i put it in quotations.

if that were true then you wouldn't be asking about fabric and aether. Pop sci sources are entertainment, not education. They make you feel good, but they don't teach you the theory.

It is good that they motivated you to ask more, but you need to recognize that if you are interested in the answers then you are going to have to unlearn a bunch of pop-sci baggage

"It" is the geometry of physics

that's why I'm here. and I ment I might not know the math, but I can invision it. beyond what their cg shows us

 

[Dale]

that's why I'm here

Excellent!

What is your math background? If you know algebra and vectors you can start with special relativity and spacetime.

 

[john-of-the-divine]

Excellent!

What is your math background? If you know algebra and vectors you can start with special relativity and spacetime.

see, that's my biggest problem, I've never been able to make myself do math. I've always had a great imagionation, and that's good, till it takes me away from what I'm trying to consentrait on.

 

[Dale]

I've never been able to make myself do math.

Then realistically I think that you have to pick a different goal. At least I don't know of a way to learn physics without doing math.

 

[rootone]

You were asking earlier about knowing the math.
I am not any kind of math expert, but I think if you can grasp Newton's Principia, then you are doing OK.
If you want to build a bridge over a river it works just fine.

 

[john-of-the-divine]

honestly, I'm trying to figure out why you think light coming from billions of light years away hasn't been altered by the space it's traveled through. if you can explain, without math, exactly what causes the effect of gravity and how it effects light, I will understand. if you can't explain without numbers, then what makes the math so infallible? but I guess that's why it's all only theoretical, which makes none of it fact. I just wanted to know how do you know %100 that the light from billions of light years away, when in fact, it's nothing more than a best guess? even though I'm no math expert, it really isn't that far fetched to believe the math could have been forced to fit a model. just because the math works doesn't make it anything less then a best guess. but, like I said, we won't know for sure till we go out there and look.

 

[rootone]

https://en.wikipedia.org/wiki/Tired_light
Probably not.

 

[john-of-the-divine]

like I said earier, I'm thinking bigger than my tiny brain can handle. thank you for the info you have shown me

 

[rootone]

You might find this is interesting,

 

[Dale]

. if you can explain, without math, exactly what causes the effect of gravity and how it effects light, I will understand

I cannot explain it without math. What good reason could you possibly have for rejecting a valid answer simply on the grounds that it contains math?

. if you can't explain without numbers, then what makes the math so infallible?

Because the math accurately predicts the results of our best physical experiments and astronomical observations. How do you expect to predict something quantitative without math?

just because the math works doesn't make it anything less then a best guess

That is why we do experiments too. To ensure that the math correctly describes part of nature.

I just wanted to know how do you know %100

"100%" is math. So you can clearly do some math

like I said, we won't know for sure till we go out there and look.

And when we do go out there and look we will have to use math to understand what we see.

Frankly, your anti math stance just comes off poorly here. If you don't want to learn math, that is fine, but don't delude yourself into thinking that an answer doesn't exist when you are simply unwilling to learn it. The deficiency is not in the answer.

 

[john-of-the-divine]

You might find this is interesting,

I'm deffenetly going to finish that later. thanks

 

[john-of-the-divine]

I cannot explain it without math. What good reason could you possibly have for rejecting a valid answer simply on the grounds that it contains math?

Because the math accurately predicts the results of our best physical experiments and astronomical observations. How do you expect to predict something quantitative without math?

That is why we do experiments too. To ensure that the math correctly describes part of nature.

"100%" is math. So you can clearly do some math

And when we do go out there and look we will have to use math to understand what we see.

Frankly, your anti math stance just comes off poorly here. If you don't want to learn math, that is fine, but don't delude yourself into thinking that an answer doesn't exist when you are simply unwilling to learn it. The deficiency is not in the answer.

I'm not necessarily anti math, and I'm not unwilling to learn it, i was just looking for explanations that don t evolve math. sorry to waste your time. thank you for at least trying.

 

[Orodruin]

I'm not necessarily anti math, and I'm not unwilling to learn it, i was just looking for explanations that don t evolve math. sorry to waste your time. thank you for at least trying.

To be quite blunt, trying to accurately explain physics without math is like trying to explain the color green to a blind person.

 

[shihab-kol]

You have to take maths into the picture.
Maths is the car which shall make your physics ride more interesting and comfortable
To get to the point:
Photons have energy and energy generates gravity according to general relativity. However the gravity force is an extremely weak force for small objects, so for the gravity between individual elementary particles or between photons the force of gravity would be completely negligible and unmeasurable.

 

[Dale]

i was just looking for explanations that don t evolve math

I don't have such answers. Scientific answers involve assumptions, math, and experiments.

 

[nitsuj]

To be quite blunt, trying to accurately explain physics without math is like trying to explain the color green to a blind person.

wow...just wow.

 

[nitsuj]

I just wanted to know how do you know %100 that the light from billions of light years away, when in fact, it's nothing more than a best guess? even though I'm no math expert, it really isn't that far fetched to believe the math could have been forced to fit a model. just because the math works doesn't make it anything less then a best guess. but, like I said, we won't know for sure till we go out there and look.

You seem to be taking a philosophical position regarding "proof "
It is far fetched to think that the math was "forced" to fit a "model"...particularly when the "model" is described by math lol

"Forcing to fit" the model is when we use words to describe the model, instead of math. Such as forcing the word "fabric" into the concept of spacetime geometry.

I explored square root once so I could understand it better. Like in all of physics math, the concept of square root has basis in the physical world.

Read about math, the concepts ect. Follow along reading the equations, look up what they mean...until you find an example of "forced to fit" and present it here; as of now I don't think "forced to fit" is well defined if at all.

 

[Dale]

I'm not necessarily anti math, and I'm not unwilling to learn it

I would recommend starting with special relativity. All it requires is high school level algebra and geometry. It will introduce the concept of spacetime and the idea of Minkowski geometry which is different from Euclidean geometry, but is still very concrete as far as being able to draw pictures. You can learn about the experiments performed to date and the alternative theories that have been ruled out. You can learn about reference frames and laws of physics and causality.

Wheeler's Spacetime Physics is highly recommended, and there are a lot of online free resources too.

 

[Vanadium 50]

just because the math works doesn't make it anything less then a best guess

Math is logic applied quantitatively. You can't give up math without giving up the underlying logic. Don't you want your answers to be logical?

 

[nitsuj]

Math is logic applied quantitatively. You can't give up math without giving up the underlying logic. Don't you want your answers to be logical?

exactly! You're good at stating things clearly.

 

[john-of-the-divine]

thank you, all of you. I know th8s is a debate I should have had with my professor, but I never got that chance. I appreciate the patience and non-buttheadness. I am, i feel, an ameture philosopher, at least some one noticed, lol. I do want to understand because because science is a big part of my belief system/philosophy. I'm just looking for undeniable truth is all. thank you, guess I have to learn the math. ouch, lol

 

[Umaxo]

I am not entirely confident in my knowladge to make replies in this forum, however, looking back to my younger age i would apprectiate someone saying this to me, so i will write it.

even though I'm no math expert, it really isn't that far fetched to believe the math could have been forced to fit a model. just because the math works doesn't make it anything less then a best guess. but, like I said, we won't know for sure till we go out there and look.

Physics without math doesn't really work.

One simple example - you know Newtonian theory of gravitation from high school i guess? Then you remember - two objects of certain mass attract each other and the closer they are, the more they attract each other (and as 1/r² which means the force goes to infinity when distance goes to zero). Someday you may come across a situation where two wet plates of glass touch each other, and glue themself together. And you remember - they have some mass, so they attract each other. Since they touched, they are very very close together, so the attraction is very strong and that explains why they seem to be glued to each other. Sounds logical. But what if they weren't wet? Then the attraction is weak. But if they are touching each other the attraction should be strong. Then you say - ok, perhaps the plate is not perfectly polished, so it is not touching each other perfectly. And since water is fluid, it will fill the empty spaces and touching will become again perfect.

And on and on you can go explaining stuff using ideas you read somewhere in pop-science books, but you will never know wheter what you said is the actual "truth" or some random mix. You need to make actual calculations to see wheter it fits what you observe or not.

Then there is problem with clarity. When you say something, you need to know what it means. What is space-time? What is electron? What is gravity? What is electromagnetism? You need math to give those words meaning that cannot be misunderstood. And when you go into more and more modern stuff, the misunderstanding will happen with bigger and bigger certainty, because language we use in our everyday lives, and experiences we have are simply too different from what is going on in the math.

When i was at high school i enjoyed so much reading pop-books like hawkings books etc., but looking back (i am doing masters degree now) i didnt learn from those books and discussions on the internet anything at all. It is only now that i can read those books and understand what they mean.

I know there has to be something that mass effects to create gravity. I used the term "fabric" as a reflection of that something knowing it's really not a fabric, hahaha. But, this field, do you think it's the "aether", just different then what was once thought to exist?

Physics doesn't care about question "what is this". It cares only about properties. We say - the thing i am talking about (spacetime) has such and such influence on this and this thing. Then we look around and see wheter those influences are observed. If yes, then we say we have good theory and we are happy. But we don't ponder about what it is. And reason is simple - because it is unknowable. All information that comes to you is only of appearances and properties. It is similar to question - do we both see the same picture in the same way? If you see red as i see green, but you call it red, because you were taught to, then you would see different picture in your mind, then the one i see. And there is no way to convey the information of what you see to me, since when it comes to me, it is my brain who interprets it and creates mental picture. So one should forget about this philosophical questions and start looking only on appearances, properties = math. The non-mathematical explanations are only to help intuition to be able to better work with math (or to catch interest of your audience), but it is not fundamental part of science.

We have model of spacetime called general relativity. With this model we can simulate things we observe in universe and ask wheter the simulations have same results as what was observed. If they are same, we are happy and confident with our model until some disagreement is found. If spacetime would slow down photons, then certianly observing distant galaxies we would found disagreements with our model. I am no cosmologist, but i know there are some problems with our models and some people work on new theory of gravity that would explain it better (and there is of course problem of quantum gravity). This discussion i leave for actual experts, but my point was this: we only concern ourself wheter the theory works or not. You said you cannot bend nothing, so be it. Call it different name than nothing, imagine whatever you like. But it has to have the same properties as our purely geometrical approach (assuming our theory works) in order to explain observed phehomena. But in the end it doesn't matter. What matters are only properties, because only those are knowable, other than that is only imagination and speculations. Good for intuition or wonder - but are not fundamental part of science.

 

[jbriggs444]

Since they touched, they are very very close together, so the attraction is very strong and that explains why they seem to be glued to each other. Sounds logical.

Please do not attack your own straw men. The centers of mass of the plates are not touching. More relevantly, if you do the integration, the force does not get huge just because the surfaces are touching. The failure is not because the math is wrong. It is because one did the math wrongly.

 

[Umaxo]

Please do not attack your own straw men. The centers of mass of the plates are not touching. More relevantly, if you do the integration, the force does not get huge just because the surfaces are touching. The failure is not because the math is wrong. It is because one did the math wrongly.

Exactly

 

[DrGreg]

thank you, all of you. I know th8s is a debate I should have had with my professor, but I never got that chance. I appreciate the patience and non-buttheadness. I am, i feel, an ameture philosopher, at least some one noticed, lol. I do want to understand because because science is a big part of my belief system/philosophy. I'm just looking for undeniable truth is all. thank you, guess I have to learn the math. ouch, lol

May I suggest Relativity for Poets by Ben Crowell (a former member of staff on this forum), which you can download for free from http://lightandmatter.com/poets/.

It's mostly text and diagrams with very little maths.

 

[nitsuj]

I'm just looking for undeniable truth is all. lol

René Descartes did the same and is a neat story.

 

[bahamagreen]

I'm saying that compared to the size of the universe, the distance to the moon is like an inch compared to 100 miles. I don't know the actual scale...

The diameter of your estimate for the size of the Universe is less than 2.6 light years.
Archimedes in The Sand Reckoner about 2250 years ago figured about 2 light years.

 

[john-of-the-divine]

Please do not attack your own straw men. The centers of mass of the plates are not touching. More relevantly, if you do the integration, the force does not get huge just because the surfaces are touching. The failure is not because the math is wrong. It is because one did the math wrongly.

hey, he said he might not have enough knowledge

May I suggest Relativity for Poets by Ben Crowell (a former member of staff on this forum), which you can download for free from http://lightandmatter.com/poets/.

It's mostly text and diagrams with very little maths.

thankyou, I appreciate it a lot.

 

[john-of-the-divine]

The diameter of your estimate for the size of the Universe is less than 2.6 light years.
Archimedes in The Sand Reckoner about 2250 years ago figured about 2 light years.

see, that's what I'm saying, is the math "calibrated" big enough? guess that's a better question. light is a photon, right? and everything else of the known energy spectrum, are those made of photons?

 

[Dale]

see, that's what I'm saying, is the math "calibrated" big enough?

We use the observations to calibrate the model.

 

[john-of-the-divine]

We use the observations to calibrate the model.

and we can only observe what we can see

 

[Dale]

and we can only observe what we can see

No

 

[john-of-the-divine]

No

ok, then we can only observe what we can observe. by you saying no is saying every thing in exictance is observable to us now. that heresy against science

 

[Dale]

then we can only observe what we can observe.

Yes, tautologically

 

[john-of-the-divine]

Yes, tautologically

exactly

 

[john-of-the-divine]

what if the Michelson Morley experiment failed because the spliter and mirrors each technically became a new "source" of light.

 

[Ibix]

what if the Michelson Morley experiment failed because the spliter and mirrors each technically became a new "source" of light.

The explanation for the null result (not a failure) is already consistent with considering the mirrors and beam-splitter as sources. This is an application of Huygens' Principle.

 

[john-of-the-divine]

The explanation for the null result (not a failure) is already consistent with considering the mirrors and beam-splitter as sources. This is an application of Huygens' Principle.

it's like looking at the sun when your under water. the sun appears to be on the surface of the water.

 

[Dale]

what if the Michelson Morley experiment failed because the spliter and mirrors each technically became a new "source" of light.

That is considered and investigated experimentally. It is called the ballistic model and is ruled out by observations of binary stars

 

[Herman Trivilino]

if you can't explain without numbers, then what makes the math so infallible?

It works! That's all there is to it. The math works. Engineers, scientists, and technicians use it to build stuff and do stuff.

Explanations are simply descriptions of what the math does for us.

 

[john-of-the-divine]

It works! That's all there is to it. The math works. Engineers, scientists, and technicians use it to build stuff and do stuff.

Explanations are simply descriptions of what the math does for us.

math is a form of explanation. it can tell us how to build something, but it doesn't build it for us.

 

[john-of-the-divine]

That is considered and investigated experimentally. It is called the ballistic model and is ruled out by observations of binary stars

can you point me to a source on that by any chance. I can't find one.

 

[Drakkith]

math is a form of explanation. it can tell us how to build something, but it doesn't build it for us.

Which is why math is integrated into scientific theories which are then verified through observations and experiments.

If you're asking why math itself is logical and self-consistent (IE why it works), that's not a question that anyone can answer.

 

[john-of-the-divine]

Which is why math is integrated into scientific theories which are then verified through observations and experiments.

If you're asking why math itself is logical and self-consistent (IE why it works), that's not a question that anyone can answer.

no, that's not my question.

 

[Dale]

can you point me to a source on that by any chance. I can't find one.

Certainly! The go-to reference is:

http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

 

[john-of-the-divine]

math is like a road map. there are many roads that can take you to get to many destinations, and you can get from any destination to any destination. from point a to point b there are many routes you can take to get you there. problem is, we are learning the routes and the stops and the destination as we go, as well as all the laws and regulations. the the routes are only straight till they hit a stop, destination, law or regulation, the routes constently swerving in and out, up and down, side to side. it all started with the first concept of numbers. from there it went, 2+2=4. adding, subtracting, multiplication, division...you get the point. we didn't know these routes till we started exploring by thinking of destinations that we can think of. we can't see the destination through the tangled mess of routes, but we know they are there. from our previous expereanc and knowledge of the routes we know, we can have a general idea of what road to take. then the next one and the next but, the deeper we go, the routes get more dense and tangled with more routes, new and different regulations. eventually, we make it to our destination. so, we look back, and we can retrace or route and we know it now. from there, there are many other roads to many other destination, or look back and say "hey, wait. looks like a different road that looks like it goes back to our last stop we just came from. let's see if it takes us back". and eventually, you make it back. a new route. two different routes between different points. and it's sometimes shorter. so now we find different routes here and there. between different stops and destinations. over time, we became so good at traversing this map of math, we start to be able to make predictions. if we went this way to get over there, then this way might take us over here. sometimes we're right, sometimes wrong. But the experience gained from the wrong path makes us better at predicting. we start to become right more often. now we are getting so deep in this map that we have to imagine new destinations. and we've gotten so in that area that it seems like we've made it to the imagined destination, when it only appears to be the destination we are looking for (previous theories). till we noticed a few key "attractions" are missing. so we go back and look for what wrong turn we made, and look for the "corrected" route from there to make it to the destination we were looking for (new theory). sometimes a route is proven and that theory becomes fact. But the route should never be looked at as the route to the destination till it's proven a fact and not just a theory because it can blind us from the real destination, and we are stuck in the apparent destintation. this is why I question the math.

 

[john-of-the-divine]

Certainly! The go-to reference is:

http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

thank you so very much.