Physics Comprehension

SkyHog

SkyHog

Touchdown! Greaser!
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Everything Offends Me
I'm on the brink of wrapping my mind around something cool...but not quite.

So light, travelling through different mediums, has a different maximum speed. This can be seen through refraction fairly easily....

Somehow, this means two things to me:
1) It is possible to look into the past
2) Energy/Mass can be created and destroyed....

But its right on the brink of my brain. Ouch, it hurts.
 
I'll have to think about 2) for a while, but 1) is easy.

The nearest star (Sun) is something like 8 light minutes away - sunlight takes 8 minutes to get here.

Another star may be thousands of light years away. When you look at that star, you are seeing how it looked thousands of years ago - looking into the past.
 
1) No, time is linear(perfectly). Light reacts differently depending on the medium, but time hasn't changed. The simplest way to think of this is the efficiency principle. Light, just like water will take the path of least resistance. You can observe this by putting your hand in a pan of water, and seeing the 'bend' where your hand enters the water. This is due to the different path of resistance for the light being refracted through the water.

2) This is a tough nut. Since we don't have a unified field yet, all you have to work with is chaos theory(big bang). Since 2 is predicated on 1 and 1 isn't true, then 2 has serious limitations. If we go all the way back to the super-matter state, then begin the big bang, it's pretty well defined that there is nothing can be created from scratch. Where things get sticky is the space-time continuum. We've proved that there is 'something' in all the empty space between matter that both bends light(the Caldwell experiments), and causes distortions in space. This entropic stuff is where you might find your matter to be created.
 
There is nothing in relativistic or quantum physics that forbids time travel.
 
I should define why I think 1) is true:

If I wave my hand behind a GIANT block of glass, and you look at it through the glass, you will likely see it happen after it did, while a person looking at it from an angle, not through the glass at all (ie - around the glass) would see it move realtime. That means, done properly, he could describe it to me before I see it.

That means, to me, at least, somehow, and I can't quite grasp it - that light can be in 2 different places at the same time....
 
I got the attached 10 years ago from I don't know where. Likely a lot of it has been supplanted with more modern thinking. But perhaps it will help stimulate your physics brain cells.
 

Attachments

SkyHog said:
Somehow, this means two things to me:
1) It is possible to look into the past
Click to expand...
Go out on a cloudless night and look up. You'll be doing just that.

IIRC the limit of our ability to see into the past is about 14.5 billion years, at present.

The problem is, we can only look into the past at things that are (were) very, very far away from us at the time, and we can only look at the past in real time (wrap your head around THAT).

2) Energy/Mass can be created and destroyed....
Click to expand...
Not unless the Laws of Thermodynamics have changed.
 
Greebo said:
Not unless the Laws of Thermodynamics have changed.
Click to expand...

This is helping me form my opinion on why the Conservation laws are wrong....that's part of why I actually care enough to wrap my mind around it....

Specifically, so I don't sound like a crackpot when I mention it to people :D
 
SkyHog said:
I should define why I think 1) is true:

If I wave my hand behind a GIANT block of glass, and you look at it through the glass, you will likely see it happen after it did, while a person looking at it from an angle, not through the glass at all (ie - around the glass) would see it move realtime. That means, done properly, he could describe it to me before I see it.

That means, to me, at least, somehow, and I can't quite grasp it - that light can be in 2 different places at the same time....
Click to expand...

This is not correct.

When I wave my hand, you see the wave almost, but not quite, immediately. Time elapses between the time the light bounces off of my hand and the time that same light hits your eyes. The amount of time that elapses is so short, however, as to seem instantaneous to our minds.

Sound works the same way, but its easier to sense the delay with sound because its so much slower. Go 100 feet away, and watch me clap my hand, then hear the clap a fraction of a second later. In reality, when you see the clap, just as when you hear it, the events have actually already happened.
 
It bears in mind pointing out that c, the constant representing the speed of light, is actually and more precisely the "speed of light in a vacuum".

If that helps. :)
 
Greebo said:
This is not correct.

When I wave my hand, you see the wave almost, but not quite, immediately. Time elapses between the time the light bounces off of my hand and the time that same light hits your eyes. The amount of time that elapses is so short, however, as to seem instantaneous to our minds.

Sound works the same way, but its easier to sense the delay with sound because its so much slower. Go 100 feet away, and watch me clap my hand, then hear the clap a fraction of a second later. In reality, when you see the clap, just as when you hear it, the events have actually already happened.
Click to expand...

Ahh, yes, but take a big enough block of glass, I mean, really, really BIG! and the wave would take much, much longer to be viewable to me, while the person looking around the glass can see it happen almost instantaneously...
 
SkyHog said:
Ahh, yes, but take a big enough block of glass, I mean, really, really BIG! and the wave would take much, much longer to be viewable to me, while the person looking around the glass can see it happen almost instantaneously...
Click to expand...

Yes, and? As I already said, we're always looking into the past. The extremely recent past, for the most part, but the past. We hear it too. All the time. Even as I type on my keyboard, I am hearing the clicks *after* the keys have actually hit the underlying tray. Nanoseconds after, but after.
 
Listen, if you really wanna blow your mind, think about this:

The speed of light dictates that the furthest back we can see right now, when we look into space, is about 15 billion years, to the moments after the big bang.

What if, however, out there, beyond the "light boundary" of 15B years, there is more universe beyond that which we are even aware of?

Think of it this way--- throw a BIG rock in a relatively calm, extremely large pool of water (a still lake). You get a big splash, and ripples. The ripples radiate out, and *for a while*, you see no other ripples inside the rings, even though the rest of the lake does have ripples.

Eventually, however, the ripples fade, and other ripples start criss crossing the ones from our splash.

Now, what if the big bang is like the big rock, the light barrier is our 'ripples', and we're just drops in the splash?

(TOTALLY unrelated to your thinking, but hey, its a chance to make your brain hurt... ;) )
 
mantakos said:
Water, glass, air, etc. The constant we call the speed of light is the speed in a vacuum:
http://en.wikipedia.org/wiki/Refractive_index

The knowledge that light has a speed generally leads to the conclusion that you can _only_ look into the past.
-harry
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While you can't look into the future, you CAN travel to it. ;)

The faster you go, the slower your clock runs. So if your friends stayed at their original speed, they will have aged faster than you when they see you again. You can see their "now" slow down if can go fast enough.

And even though you can look into the past if it is far away, no matter how fast or how slow you go, it will be the present by the time you get there. Go fig.
 
Greebo said:
Yes, and? As I already said, we're always looking into the past. The extremely recent past, for the most part, but the past. We hear it too. All the time. Even as I type on my keyboard, I am hearing the clicks *after* the keys have actually hit the underlying tray. Nanoseconds after, but after.
Click to expand...

Right - so does that not prove then that matter can exist in 2 different places at the same time, and therefore, it can be created/destroyed?
 
Dart said:
While you can't look into the future, you CAN travel to it. ;)
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Indeed! I constructed a time machine. The intrepid time traveler is enclosed in a chamber which transports him one minute into the future. The process takes sixty seconds.
 
SkyHog said:
Right - so does that not prove then that matter can exist in 2 different places at the same time, and therefore, it can be created/destroyed?
Click to expand...

No it proves that the matter at a given instant in time can be perceived from two different locations at different instants in time.
 
SkyHog said:
Right - so does that not prove then that matter can exist in 2 different places at the same time, and therefore, it can be created/destroyed?
Click to expand...

No, not at all. I think you may be confusing the light waves and sound waves that travel with the object that caused them to travel?
 
We are all travelers in time, moving forward at the rate of 1 sec/sec as we perceive it. And, to a certain extent, we can change the rate at which we travel relative to others travelling at a different rate through space. Thus, we can cause time to slow down for us relative to that experienced by others -- if we go fast enough relative to them.

However, we have yet to figure out how to travel backwards in time relative to our normal forward motion through it. Despite the concepts considered in a number of Star Trek episodes (which suggest that if we exceed the speed of light, we can reverse the flow of time as we perceive it), we haven't yet figured out how to go faster than light within our space-time continuum. Einsteinian physics suggest this is impossible because the amount of thrust required to further accelerate a body increases to an infinite value as we approach the speed of light. However, 70 years ago we thought that about supersonic flight, and there are some things we now know which Einstein didn't, so the matter isn't completely closed.
 
Right - so does that not prove then that matter can exist in 2 different places at the same time, and therefore, it can be created/destroyed?
Click to expand...
No, it means that effects that originate from the location of an object take time to propagate, and so they may be perceived at different times by observers at different distances. The object isn't "at" your eye, you can never view it "in real-time", you can merely perceive light that reflected off the object at some time in the past.

If you're the King, and your army is fighting 500 miles away, it will take some time for a messenger on horseback to reach you with news of the fighting. Everything you ever hear will be old news by the time it reaches you. If the enemy's ruler is 250 miles away from the fighting, news will reach him faster than you. He knows about everything before you do.

Could he tell you about it before you hear from your own messengers? Not until iPhones are invented, because there's a propagation delay involved in him communicating with you, as well, absolutely nothing happens immediately.

Is there any connection between when battle events occur and when the respective rulers hear about them? No. The events don't "occur" when each ruler hears about them.
-harry
 
SkyHog said:
Right - so does that not prove then that matter can exist in 2 different places at the same time, and therefore, it can be created/destroyed?
Click to expand...


Argh, you need to get off this precondition. The word 'time' defines a continuum. when you say things like "same time" you put a precondition on time that cannot exist. Yes, two things can exist as the same time. Earth and Moon both exist at the same moment in time. Time doesn't start, stop, move, bend, fold, spindle or mutilate. It is the ultimate continuum. Once you understand the linearity of time, you'll be on your way to contradicting your theorem.

BTW, you wave motion example is a laymans explanation for space-time continuum, but you're leaving out the time continuum element of the deal.
 
roncachamp said:
Indeed! I constructed a time machine. The intrepid time traveler is enclosed in a chamber which transports him one minute into the future. The process takes sixty seconds.
Click to expand...

FOOL! This is the internet, now anybody can say it was their idea and you stole it. :D:D:D
 
Greebo said:
What if, however, out there, beyond the "light boundary" of 15B years, there is more universe beyond that which we are even aware of?
Think of it this way--- throw a BIG rock in a relatively calm, extremely large pool of water (a still lake). You get a big splash, and ripples. The ripples radiate out, and *for a while*, you see no other ripples inside the rings, even though the rest of the lake does have ripples.
Eventually, however, the ripples fade, and other ripples start criss crossing the ones from our splash.
Click to expand...

You may not be too far off what's being theorized and possibly being observed. A while back I was poking around at cosmology, really horrifically long time periods and such and ran across some interesting stuff.

15B LY is the time boundry we can see. The theories are that the Universe is actually larger than 15B LY due to dark flow expansion and inflation during the meantime to the order of something like 158B LY.

They're actually observing potential gravitational attraction beyond the observational Universe. Here's part of it: (I can't find the other pile of stuff I saved somewhere at the moment)
http://www.spaceflightnow.com/news/n0809/23darkflow/
If that's definitely proven, the pool we're in just got really really deep.

Once you start looking at the expansion rate and where that'll end up eventually, it's, um, brutal. The Universe has no compassion for our little measly passing existence. Interesting stuff but it's a rough neighborhood.


Calling Kath Rawlins to the thread. (Hey, are you still around? Haven't seen you in a while)
 
Ron Levy said:
We are all travelers in time, moving forward at the rate of 1 sec/sec as we perceive it. And, to a certain extent, we can change the rate at which we travel relative to others travelling at a different rate through space. Thus, we can cause time to slow down for us relative to that experienced by others -- if we go fast enough relative to them.

However, we have yet to figure out how to travel backwards in time relative to our normal forward motion through it. Despite the concepts considered in a number of Star Trek episodes (which suggest that if we exceed the speed of light, we can reverse the flow of time as we perceive it), we haven't yet figured out how to go faster than light within our space-time continuum. Einsteinian physics suggest this is impossible because the amount of thrust required to further accelerate a body increases to an infinite value as we approach the speed of light. However, 70 years ago we thought that about supersonic flight, and there are some things we now know which Einstein didn't, so the matter isn't completely closed.
Click to expand...


I've figured it out, but I'm not telling any of YOU!

See you yesterday!
 
Ron Levy said:
We are all travelers in time, moving forward at the rate of 1 sec/sec as we perceive it. And, to a certain extent, we can change the rate at which we travel relative to others travelling at a different rate through space. Thus, we can cause time to slow down for us relative to that experienced by others -- if we go fast enough relative to them.
Click to expand...

I just noticed that you defined time in units of an acceleration, although it's numerator is a unit value. This is sometimes what leads people who have a decent understanding of pre-calc to the idea that time can be stretched. Of course, the derivative is perfectly linear, it's a round-about way of defining time.

Also, your statement that we can cause time to slow down is not correct, even from a relativistic sense. Time does not change, we/they change in relation to that constant which is time.
 
...pass the doob, man...
 
Nick,

Do you understand the bullet thing yet? 'cuz if you don't, nobody's gonna listen to you. ;)
 
I found the best explanation of relativity to be Einstein's own book. Don't be afraid to read him, he was actually an easily understood author. It's the folks trying to "explain" what Einstein said that gum up the works! A free English translation of the 1929 classic is available free online here:

http://books.google.com/books?id=gQ...&dq=inauthor:Albert+inauthor:Einstein#PPR6,M1

Yes, it has math but, the math is there to illustrate the concepts he writes about.

Also search for a copy of his train "mind experiment". It helps visualize the basic concepts.

Beware: for every Einstein theory or paper you find on a search engine there are at least half a dozen debunkers and "Einstein was wrong!" experts.
 
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Greebo said:
It bears in mind pointing out that c, the constant representing the speed of light, is actually and more precisely the "speed of light in a vacuum".
Click to expand...

An even better question, is the speed of light (c) the same throughout the universe?
 
docmirror said:
Also, your statement that we can cause time to slow down is not correct, even from a relativistic sense. Time does not change, we/they change in relation to that constant which is time.
Click to expand...
I think I was trying to say that time appears to slow relative to the other observer. It's our perception of the passage of time, not actual change in the rate time moves.
 
docmirror said:
Time doesn't start, stop, move, bend, fold, spindle or mutilate. It is the ultimate continuum. Once you understand the linearity of time, you'll be on your way to contradicting your theorem.
Click to expand...

Time is linear only in a relative neighborhood.
Folded space/time allows for non-linear events to occur.
Linear time does not allow for time travel as one must also calculate the position in space for any given time. This is the flaw in most science fiction.
Think about two people on opposite sides of a rotating merry-go-round trying to throw a ball to each other.
 
john smith said:
An even better question, is the speed of light (c) the same throughout the universe?
Click to expand...

Barring evidence to the contrary, yes. If not, then c is no longer a constant, and Einstein was screwed.
 
john smith said:
Time is linear only in a relative neighborhood.
Folded space/time allows for non-linear events to occur.
Linear time does not allow for time travel as one must also calculate the position in space for any given time. This is the flaw in most science fiction.
Think about two people on opposite sides of a rotating merry-go-round trying to throw a ball to each other.
Click to expand...

What is there to think about?
 
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