Stephen hawkings' concerns about ET

[omnibot]

"People need to remember that while traveling close to the speed of light time warps, we know this. So, we would see that a spaceship traveling towards us that seemed to take 100,000 years to get here from our point of view. However if it were traveling at 99.99% the speed of light, the object would only age about 26820.5 years, rounded some big numbers so it may be off by 10 years or so.
If one could travel at the speed of light some people (smart nasa fucks) believe time could be suspended for the object.
Second, traveling faster than the speed of light might travel back in time, this theory has no evidence but is one of the leading theories."

I have a question about relativity that I've never felt I've gotten quite answered to my satisfaction. If things are truly relative then why would one object's time be slowed down compared to the other one? What gives one object "priority"? When an object is moving very quickly relative to another object it is impossible to know which object is actually moving. In fact "actually moving" doesn't mean anything. So why would one objects time be warped/slowed down while the other object's time is not?

[omnibot]

I tend to think that our experience of the universe does have some truth in it, but not the whole truth. We experience 3 macroscopic spacial dimension and 1 time dimension. Even though there may be way more to space and time than we can perceive, our experience of space and time is not necessarily false, just not the whole truth.

"our physicality limits us to only see this specific side of the greater oneness"

right. that's a more concise way of saying what I think. Sorry, didn't see this until just now.

"it is impossable for a 3D object to comprehend a first or second dimention."

What exactly do you mean? I don't have too much trouble comprehending a two dimensional world. A fourth spatial dimension on the other hand is much harder.

"it's our failure if we cannot quite wrap our minds around
the concept properly."

That's part of what is so fascinating about physics. Our mathematical understanding of the universe goes much further than our conceptual understanding

[taoistshredder]

"I have a question about relativity that I've never felt I've gotten quite answered to my satisfaction. If things are truly relative then why would one object's time be slowed down compared to the other one? What gives one object "priority"? When an object is moving very quickly relative to another object it is impossible to know which object is actually moving. In fact "actually moving" doesn't mean anything. So why would one objects time be warped/slowed down while the other object's time is not?"

That's the thing - it's relative. Time isn't really doing anything - time is relative - it's really your molecules that are speeding up to the point where what was previously seen as "real time" can no longer percieve your molecules because they're moving too quickly. But it's just too quickly for them - to the one moving quickly it seems like time is slowing down, but it's not - time stays the same, it's actually that one person speeding up.

I can't see how a person can imagine a one or two dimentional figure. The first dimention is really hard, and the second is just a plane. How can a 3D object ever possibly be able to even imagine an obect that has width and breath but no height, or height and width but no breath? In our dimention it doesn't exist and we can't even comprehend it. No matter how you try, whatever object you imagine will still be held by the laws within your dimention because that's where you're stuck. It's a lot easier to imagine a 4th dimention without any physicality than it is to deconstruct what is percieved as physicality into lesser dimentions. Let me ask you this - how can you imagine a two dimentional object? How, even in your mind, can you see it, as light waves are 3D? i.e. even a light projection on a wall, percievably a 2D object, is still not because the image projected as some depth to it, regardless of how small it is or how fast it's moving.

[omnibot]

"to the one moving quickly it seems like time is slowing down"

and how do you tell which one is moving quickly? Also, someone moving very quickly experiences no subjective slowing down of time within their time frame. Any warpage that happens happens is in comparison to something outside of their reference frame.

"it's really your molecules that are speeding up to the point where what was previously seen as "real time" can no longer percieve your molecules because they're moving too quickly. But it's just too quickly for them"

You lost me. Would you mind explaining this idea a bit?

"how can you imagine a two dimentional object?"

Like this: I can't visualize a two dimensional world (very well), but I can, conceptualize one without any trouble at all. I just imagine a cartesian coordinate system. With three dimensions you have an x,y, and z axis. Take away the z axis. There simply does not exist a coordinate for depth. simple enough. I have a very clear concept of a two dimensional coordinate system in my mind. Take away the y axis, and you have a one dimensional coordinate system. The way to do it is not to think of the y and z depths as infinitely thin, but entirely non-existent.

[taoistshredder]

"and how do you tell which one is moving quickly?"


You can't. It's relative to the objects in motion. There is no universal "faster," it's all perception of the objects in play. If two people are running along and you're watching, you can tell their speed but only because you are at rest - they are travelling faster than you. But to the two runners, you're standing still, and they are moving at the same speed as each other; each runner sees the other runner not as moving fast (er), but moving at the same speed. But as a car passes them, they see the car is moving fast, while the car sees them as slow, practically not even moving in comparison. Now how easy is it to see you on your chair on your porch from the car, and what do you look like; what does the car look like? The car can barely notice you and for you the car is almost a blur, but the only reason for that is the speed at which you are each travelling. Relativity - it's all relative. This is about as easy as I think I can make it for you.

I took plane geometry, as well, and I can also conceptualize and visualize what I might think to be an x/y plane, but there is no way to actually do it - it must have depth. Even if you drew lines on a piece of paper to indicate a 2D plane, there is depth there in the marks made and the width of the paper. If you want to get anal-retentive, when you imagine things in your mind you use 3D electronic impulses that are interpreted by your brain to make you see what you want to see; for you, these 3D objects present an illusion of what your 3D mind thinks 2D might look like.

[omnibot]

"You can't. It's relative to the objects in motion."

EEEExactly

"But to the two runners, you're standing still, and they are moving at the same speed as each other;"

The whole point is that for the runners they are stationary, and you are moving in the opposite direction. Isn't it?

"If two people are running along and you're watching, you can tell their speed but only because you are at rest - they are travelling faster than you."

But if this was happening in space without the reference point of the earth, they aren't travelling faster than you. They see you moving, and you see them moving.

So here's my question. A spaceship blasts off of the earth and goes to Alpha Centuri at 99.9999% the speed of light. At Alpha Centuri the spaceship turns around and comes back. When it gets back to earth, where has the most time passed? On the spaceship, or on Earth? Because motion is relative I don't see any reason why one's time would be warped over the other.

[shedthemonkey]

Fun discussion. I actually had a course in Relativity back in college (This is a physics monkey heavy in Lasers) and most people don't know that

E = m * C^2

is the SIMPLIFIED equation.

I don't have the book here at the moment (buried somewhere in the garage) but there is a big fraction on the right hand side that approaches 1 as the speeds decrease and has time as another variable. Spore print bookmark to to the first who digs up the relativistic equation(s) and posts them here for people to see...to lazy to search.

It is mind warping stuff. We used to sit around in class and contemplate things like (ACTUAL TEST QUESTION): Assume your car can go the speed of light. You turn on the headlights. Describe what happens.

Fun stuff. We used to discuss these things sober...wish I would have been a little more open to weed back then...would have been some even more deep discussions! Of course I likely wouldn't have passed my courses cuz it makes me fuzzy...

As you approach the speed of light from some arbitrary point of reference things get longer and time slows down when veiwed from the reference. To the one who accellerated it all seems completely the same except when the twin goes to the nearest star at 0.5c and then comes back ump-teen years later, his twin on earth will be MUCH older than him. The math says so. There have been actual experiments with atomic clocks, synchronized on the ground and then flown at supersonic speeds (gotta love the SR-51 Blackbird) and then compared with the one on the ground and the one that flew is measurably slow!

To answer the test question above: Nothing happens other than the filliments in the lights get hot, you will not see a light beam out in front of you because the light is also traveling the same speed. Photons will not be able to go out and reflect off of stuff for you to see the reflected waveform.

We started the course with the quote from Einstein, roughly paraphrased here: Those who claim to understand relativity are lying.

[taoistshredder]

"Those who claim to understand relativity are lying."

lol
Exactly.
The answer to your question, I think, would be more time was observed on earth than the ship (given the premise that humans could somehow withstand those speeds). For any human on the ship that has a concept of time being linear the trip to alpha centauri would be virtually instintanius. Then again, the organism itself would more than likely be ripped to shreds. So if we weren't human and we were just dealing with theoretical energy out in random space-time then there is absolutely no difference between what I define as a second or a day or a lifetime; however, that's not the situation. We've taken our relative perception of the world and how we live in it to better define our existence; I'm the first to admit it's arbitrary and pointless, but then again, one could make the same argument for the whole of existence. Fortunately for us, space-time knows no point: there is no point because a point would be pointless...everything just is.

[omnibot]

could this be the equation you're looking for? Delta T1= Delta T2 (1-v^2/c^2)^-(1/2)

Where Delta T2 is a time interval for the "moving" object, and Delta T1 is the same time interval as seen by the "stationary" object.

"The answer to your question, I think, would be more time was observed on earth than the ship"

That is what I've always heard. And yet the exact same equation could be used from the ships perspective, and the earths time would be relatively slowed down.

"Then again, the organism itself would more than likely be ripped to shreds."

Simply going very fast wouldn't put any stress on the organism I think. It would just have to deal with the acceleration to reach those speeds.

"It is mind warping stuff. We used to sit around in class and contemplate things like (ACTUAL TEST QUESTION): Assume your car can go the speed of light. You turn on the headlights. Describe what happens."

Seems like a strange question as no object with mass could ever go the speed of light. The universe has no provision for what would happen if an object went at light speed. If an object is going less than the speed of light, even if it is going 0.9999999c, light will travel away from it at c because of time dilation. The speed of light is constant. Doesn't matter how fast you are travelling or in what direction.

[shedthemonkey]

Originally Posted by omnibot

could this be the equation you're looking for? Delta T1= Delta T2 (1-v^2/c^2)^-(1/2)

Where Delta T2 is a time interval for the "moving" object, and Delta T1 is the same time interval as seen by the "stationary" object.

---snip---

"It is mind warping stuff. We used to sit around in class and contemplate things like (ACTUAL TEST QUESTION): Assume your car can go the speed of light. You turn on the headlights. Describe what happens."

Seems like a strange question as no object with mass could ever go the speed of light. The universe has no provision for what would happen if an object went at light speed. If an object is going less than the speed of light, even if it is going 0.9999999c, light will travel away from it at c because of time dilation. The speed of light is constant. Doesn't matter how fast you are travelling or in what direction.

First, yes, that is one of the equations. That is the time dilation equation. There is one for delta mass and one for delta length. The other equations have the same form. There is a messier version of the E=mc^2 that includes the time term in it too. Buried in a box somewhere and cant locate the book...By the way, some really wonderful brain twisters can ALMOST be explained in laymans terms in the book Alice in Quantumland by Robert Gilmore. Did find THAT book but it doesn't seem to have the equations in it.

So, PM me a safe addy if you want Omnibot and you can have either a HAW, TEX, or Z print bookmark.

Now on your last point, yes it is a strange question but try not to get knitpicky about the GIVEN in the question. Assuming something is impossible is usually the way to stifle discussion rather than try to understand. The math says that EXACTLY at the speed of light we do not know for sure what happens as the equations blow up. We can guess that time effectively stops, mass becomes infinate and that length becomes infinate. Nothing in the equations say we can not actually go the speed of light or faster, just that the math becomes problematical. Einstein still hadn't solved it completely by his death. No one has. Still just a model, tho a good one.

[omnibot]

"Nothing in the equations say we can not actually go the speed of light or faster, just that the math becomes problematical."

I don't think that's true. Because mass goes to infinity as your speed goes to c, you would need an infinite amount of energy to accelerate the last little bit. No matter how much energy you had, it wouldn't be sufficient to get you to c. I'd say the equations clearly imply that reaching the speed of light for any mass-endowed object is impossible. Sorry, I'm not trying to nitpick. . I suppose you're right that IF an object were to go the speed of light, time would stop and space would collapse.

Yeah! I get a bookmark. Thanks! I'll PM you in a few days. Here, I dug up a few more equations. I think this is the energy-mass one you are thinking of:

(mc^2)=E^2-(pc)^2

has time included in the form of momentum: p= mass*(distance/time)

Here's the length contraction equation:

Lmeasured=Lpropor/((1-v^2/c^2)^-(1/2))

And here is for mass:

Mmoving=Mrest/((1-v^2/c^2)^(1/2))


Well I'm still left with my problem of why one person's time is dilated over another's. I've actually had the chance to talk to several physics professors about the problem. Most vaguely mention a connection to general relativity and acceleration. The last one I talked to said he would research the paradox a bit and get back to me. Suppose I might have to carry the question to my grave with me.

[shedthemonkey]

LOL, you wouldnt be the first to go to the grave not knowing that!

Lets go into meta-physics for a second to show that the speed of light thing is much a question for philosophy as for physics. Assume for the moment that we are all the same connected energy patterns at the very heart of this illusion we call life and that mass itself is an illusion. The simplification of E= mc^2 from the form you mention (good job on finding all those, you earned that bookmark!) is only valid for things with no mass, such as photons, or for the ONE who is everything who is already infinately everywhere and outside time. If we are really just energy at the core, then physisists (--lol that cant be right sp...oh well) have a real problem of figuring out what we really are made of. They havent been able to figure out how the stuff of life has pattern when everything we assume has to be made from something. For instance what are you? A bipedal hominid? But what is that? A collection of chemicals and electrical impulses? what are they? chemicals are made of atoms? electrical impulses is just energy...ok, what are atoms? made of neutrons, protons, electrons. what are they? quarks and mesons and ??? um...Hey look over there! The GOODYEAR BLIMP!! and they can't answer what makes up the pattern of life that is more than 99% empty space, or dark matter , or whatever you want to call it. Get down to the nitty gritty and we have NO real idea of what we are, except some of us postulate these interesting ideas that we exist because we can ask these questions. See? At this level, Philosophy is just as important as Physics. LOL.

Damn, I need to go to bed. Anyway, this is a fun discussion. Reminds me of college.

[taoistshredder]

Check this out: http://twm.co.nz/hologram.html

"At this level, Philosophy is just as important as Physics."

Thank Buddha, because I'm no physicist.

[the_other_chap]

"Nothing in the equations say we can not actually go the speed of light or faster, just that the math becomes problematical."

As I understand it, there's nothing that says objects (at least particles) cannot travel faster than light, but it is impossible to accelerate them to or through the speed of light (due to the infinite energy required). Particles which do travel faster than light (tachyons) have to have been travelling faster than light at the time of their creation (the BB).
I suppose this poses the question "if you could slow a tachyon to below the speed of light, would it release infinite energy in the process of decelerating through lightspeed?"
Since no tachyons have ever been observed, it's a bit of a pointless conjecture

[vrooota]

LOL you guys are all waaaaaaaaay to freakin smart in the physics dept. Can't we just go back to little green men so I can participate?

[shedthemonkey]

Says you Vroota, I barely passed all my courses. But they give a BS degree to any ol monkey who fills a seat for 7 years these days...LOL

[omnibot]

"As I understand it, there's nothing that says objects (at least particles) cannot travel faster than light, but it is impossible to accelerate them to or through the speed of light "

good point. But tachyons also don't have any real mass. So I maintain that no mass-endowed object can travel at or faster than the speed of light, and that the equations say so.

"what are atoms? made of neutrons, protons, electrons. what are they? quarks and mesons and ??? um...Hey look over there! The GOODYEAR BLIMP!!"

yeah it's kind of fun that even the most fundamentally obvious part of our universe (for us at least), matter, is completely beyond us to explain. Energy too. What the hell is energy? Hell if I know.

"except some of us postulate these interesting ideas that we exist because we can ask these questions."

I always get a related sort of feeling when I'm tripping and asking these sorts of questions. That the question is somehow inextricably tied to the answer itself. I've never really been able to incorporate it fully into my own cosmology though. I've never come to the conclusion that there is any exterior meaning or reason behind existence. It seems that the search for meaning is a very human quest, and that the human level is the best level to look for meaning on. So we give meaning to each other, we give ourselves meaning, and where we can't find meaning, we learn to not sweat it.

That said I also feel that there is an ultimate hrrrmmmmm maybe duty is the right word, that we humans have. To branch out in every possible direction and take advantage of the quirk of existence that is consciousness.

[taoistshredder]

Basically what we're saying is that a human would have the potential to achieve the speed of light and according to Einstien absolute Energy; we know that as matter accellerates particles tend to come off of it, so the accelleration of getting our masses up to light speed would tear us to pieces. We still might be moving at light speed...but we'd be dead. Is the only way for an object to achieve light speed to have no mass? Does a lightwave have a mass? It is a 3D object, a wave, but do waves have mass? Have any of you read Tthe Holographic Universe? http://twm.co.nz/hologram.html Love to hear your opinions on the theory.

[the_other_chap]

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Originally Posted by taoistshredder

we know that as matter accellerates particles tend to come off of it,

Do we?

Have any of you read The Holographic Universe? http://twm.co.nz/hologram.html Love to hear your opinions on the theory.

Yes, it's an fascinating theory, and gives us an interesting slant on quantum entanglement, but there doesn't appear to be any testable evidence that it's correct.

[taoistshredder]

I would argue that any matter will eventually lose particles as it accellerates - granted trowing a clump of dirt will lose pieces faster than a javelin, but if you got that javelin going fast enough it would start to break apart. Is there matter that doesn't adhere to this principle? And does light not have mass? Is that an explaination?

[the_other_chap]

Originally Posted by taoistshredder

I would argue that any matter will eventually lose particles as it accellerates - granted trowing a clump of dirt will lose pieces faster than a javelin, but if you got that javelin going fast enough it would start to break apart. Is there matter that doesn't adhere to this principle?

Sorry, but yes. All of it.
Matter does not spontaneously "slough off" from accelerating objects.
You're using the example of a clump of dirt, which obviously does disintegrate when thrown, but that's due to it's weak mechanical structure, air friction and gravity. If you could smoothly accelerate the javelin to lightspeed in a vacuum, it would not disintegrate.

[vrooota]

Originally Posted by omnibot

"

That said I also feel that there is an ultimate hrrrmmmmm maybe duty is the right word, that we humans have. To branch out in every possible direction and take advantage of the quirk of existence that is consciousness."

That is a beautiful paragraph my friend
I think it might explain why we dose too, or at least part of the reason why I trip. good stuff

[taoistshredder]

So when a comet is flying through space,
does it have a tail?
Is this tail just due to heat or what?
I understand the idea that there's no friction in space
but I'm not saying friction causes the deterioration,
I don't see how the structural integrity of an atom could withstand
the acceleration involved in achieving light speed,
regardless of how smooth the ride was.
But it's obvious I'm missing something here.
Again: does light have mass?
If I accellerate in space, do I feel the accelleration?
This is to say, does accelleration cause gravity,
or does gravity cause accelleration?
If I accellerate fast in my car, I get pushed back into my seat,
that feeling of torque is gravity, right?
Like "Gs" in a plane.
So if I'm in space can I not feel myself accellerating?
Answers to these questions I must have, yes...

[the_other_chap]

Originally Posted by taoistshredder

Answers to these questions I must have, yes...

That's a lot of ground to cover! You don't seem familiar with Newtonian physics, so I don't think I can explain all of that without finding some links to explain Newton's laws of motion and a bit of background first.
Hang on.... give me an hour or several........

[taoistshredder]

Physics?
That's a science, right?
lol
If you need me I'll be researching; ya'll know how I am...

[I_am_me]

Its really hard to be all stoned and jump back into the thread. I read the first page, missed a few days of conversation...and here we are.

I feel like the Towel off of Southpark.

I'm so high, I don't have any idea whats goin on.

[omnibot]

I don't know much about comets, but I think the tail of a comet is caused by radiation from the sun knocking off little particles of ice and what-not from the comet. From what I've collected a comets tail has nothing to do with its direction of motion. The tail is always pointed away from the sun.

"I don't see how the structural integrity of an atom could withstand
the acceleration involved in achieving light speed,
regardless of how smooth the ride was."

Imagine an object moving at 10 meters per second. It starts accelerating so that every second it gains 1 meter per second. So it's acceleration is 1 meter per second, per second. Or 1 meter per second^2. Now the forces one would feel from acceleration at 1 meter per second^2 are fairly mild. That object can keep accelerating as long as it wants at that rate and no additional forces will be felt. After quite a long time, the object will be going near the speed of light. If it weren't for the fact that objects gain mass as they near the speed of light you could accelerate something @ 1 meter per second^2 right up until it hits light speed. The stresses on the object would not increase.

"does light have mass?"

Sort of. light does not have "rest mass" like other things in our universe. It has mass only because it is in motion, and then only because it is moving @ the speed of light. (see note)

"If I accellerate in space, do I feel the accelleration?"

If you accelerate in space you do feel the acceleration. Because everything has inertia (things seems to want to stay in the state of motion they is currently in. no one knows why) your organs and things will resist the acceleration of your spaceship or whatever and you will feel yourself being pulled towards the back of your spacecraft.

"This is to say, does accelleration cause gravity,
or does gravity cause accelleration?"

Neither really. One of the statements of general relativity is that acceleration and gravity can be mapped out in mathematically equivalant ways. There is still doubt about what this really means and how closely one can tie the two. If you were trapped inside a sealed box, you would not be able to tell whether you were being acted upon by gravity or were undergoing acceleration. This doesn't mean that you are feeling the effects of gravity when you accelerate, or that while standing on the Earth you are undergoing acceleration.

"If I accellerate fast in my car, I get pushed back into my seat,
that feeling of torque is gravity, right?"

That feeling is inertia. You feel your body being pulled towards the back of the vehicle because it wants to stay in the state of motion it was.

"Like "Gs" in a plane."

G's in an airplane are also caused by an acceleration and not by gravity. They call them G's out of convention, since one Earth gravity is a unit of measure we are all familiar with. So if you are pulling 15 G during a turn, it means you are undergoing acceleration equivalant to 15 Earth gravities, not that you are being affected by some sort of gravity 15 times stronger than Earth's gravity.



Note: This is a bit sketchy as I'm not quite sure about this, but from what I've gathered by talking to physicists there seem to be two very seperate mass properties. One is inertial mass, and one is gravitational mass. When objects are accelerated to near the speed of light it is their inertial mass that increases and resists further acceleration, while their gravitational mass stays the same. So an object traveling at near the speed of light will not attract matter more than it did when it was stationary.

Light, I believe, only has gravitational mass, but no intertial mass. It does not resist motion at all, and therefore can only travel at the speed of light. But it does attract other objects slightly, and is slightly attracted by them.

[destroy_erase_improve]

man
i opened this thread and was following along fairly nicely, but with no schooling and explaination of the equations being presented i am totally out of the loop now of this thread.

i dont have much to add to this thread other than that i believe there is life outside of our planet, and i do believe that at some point they have visited this planet. in the past and currently.

i dont know if i think they will be hostile, nor do i know if hey will be enlightened.
i just know i believe that somewhere, out there, life exists. it may not be anything like us, or anything that we can comprehend, it may use gases or minerals that we have never even encountered to exist. dunno. but i find it very closed minded to believe we are the only ones.

sorry about breaking up all the complex posts guys. just wanted to kinda chime in.