Breaking the Speed of Light

Hi Guest.

The short answer is that you can make it as high as you like and you will never travel at the speed of light.

The long answer is that as you make the tower higher and higher, the Earth's rotation will slow down, just like a ballerina's rotation slows down if she extends her arms. If you could build an 'infinitely high' tower that is fixed to Earth, the rotation of Earth will stop... Why? Because the angular momentum of you (and the top of the tower) will need to be infinite if Earth rotates at all!

Jorrie

Yes and just think of the stairs!

You don't need stairs - you climb as you build.

Your wife will need the stairs to get food to you and to borrow your credit card.

My wife will only bring the food. She already has all my credit cards.

And she'd still bring you food?

"Where were you when the boys were building a ladder to Heaven to see their friend Kenny?"

Oh BUGGER! Thats that then!

So building higher and higher skyscrapers would be the best way to enlarge the days in some nanoseconds.

Jaime Soto

I vote for staying on the sunny side. Unfortunatley that will leave most of you on the Dark Side (where's Luke when you need him)

He's with Kate and Hasse in the barn with Papina.

There is no dark side of the moon, it's all dark!

However, if you had a powerful enough flashlight to put a beam out to a point where moving it would cause the beam to sweep across space faster than the speed of light, that would work. The wave front is not subject to the speed of light because no mass or energy is displaced by the beam sweeping the night sky.

Vermin,

I have seen the experiment you are referring to.

How does it get there before the beam?

Anti-matter? or Dark Matter?

That's some attraction, isn't it?

It doesn't. It gets there when it does. Photons will be arriving at their designated point after you turn off the flash light.

Orion - "Dude check it out, there's like a beam in the sky!"

"Cool, let drive over there and see if they want ta party!"

"Yeah, like my dad totally owns a dealership, so they won't want ta mess with us..."

"Yeah, maybe there's space-babes over there"

"Uhu! Let's go see what's up!"

"Party on, dude!!!"

should i wear a helmet if i were on top? - If it was possible to break the speed of light by building that high.

Yes but with:

A strong visor for the wind (or absence thereof)

Ear plugs for the supersonic boom.

vision slowdown or anti shift equipment.

strong expanding struts to prevent the back catching up with the front

multi-multi purpose watch.

Whatever - If breaking the speed of sound produces a supersonic boom - breaking the speed of light may produce a what? - Big Bang?

breaking the speed of light may produce a what? - Big Bang?

Nope, a little flash of light...the Cherenkov effect.

"Nope, a little flash of light...the Cherenkov effect."

What an anticlimax!! It is like a murder with a fake gun (pip-pip)

I would expect a Chernobyl (spelling) flash.

Reaching the speed of light one may find him selves only a fraction of a second in front and behind.

If one go any faster he may see where the rubbish i am talking about is coming from.

If you begin at a place on earth that is located coexistant with the axis of rotation(somewhere around the north or south poles), your mass times speed would contribute a negligible amount to the angular momentum of the total (angular momentum of the earth plus the angular momentum of your body). If you then walked toward the equator the total angular momentum wouldn't change but your speed relative to the axis of rotation would change. It would reach a maximum of around 1000 miles/hour(The earth rotates once per 24 hours and is about 24000 miles around). While the total angular momentum of the system(you plus earth) remained the same, your speed increased as your distance from the axis of rotation increased. So I disagree that the conservation of momentum causes your speed to remain constant as you move further away from the axis of rotation. They are inversely related but not inversely proportional I don't think. They would only be inversely proportional if the earth and you were of the same mass. So, assuming infinite mass for the earth and infinitely small mass for you, the earth would maintain a constant angular velocity. If your going about 1000 miles an hour at a radius of 4000 miles, then to go 186000 miles per second you would have to move out to a radius of 186000mi/sec*3600sec/hr*4000mi/1000mi . The height above the surface of the earth would be that value - 4000mi. The speed of light in the example is rounded off, as well as the radius (4000 miles = approximate distance from axis of rotation when standing on surface of the earth at the equator). The actual number would be somewhat higher because the earth isn't infinitely massive and you aren't almost massless. The technology to build a fixed tower structure to place you that far up doesn't exist currently though it might be possible, albeit impractical. You would need special equipment to survive in space and if you did achieve the speed of light, I think you would change into energy. I wouldn't try it. Changing into energy isn't healthy.

No, you just have to change your underwear.

Or HotPants.

Accepting all the other comments that it's impossible, very roughly:

speed of light: 186,000 miles per second

speed at the equator: 1000 miles per hour.

Radius of earth: 4000 miles

ignoring the fact that the earth is going round the sun (and the sun round the centre of the galaxy etc.)

height of tower = 186*60*60*4000 miles = 2.7 billion miles

The sun is only 90 million miles away: so yes you'll need your hard hat.

He would have to include a huge loop in the tower to miss the sun.

Just imagine the amount of paperwork required to order, pack, transport the material.

Randal can you calculate the diameter of the tower if say 50% of the earth can be used for the tower.

John: 11, 35.

Already done, God got scared and confused the builders

Genesis 11- 1 to 5

http://www.biblegateway.com/passage/?search=Genesis%2011:1-9

Well, what the hell was he so pissed off about?! I thought he wanted his creation to do great things. Just not on his street corner? I get it.

And while I'm at it, seems the problem with breaking the speed of light lies within the frame of reference. So I suggest you probably can break the light barrier as long as you don't know your reference frame... This can be accomplished by closing your eyes really tight, putting you fingers in your ears, and shouting "LALALALALALALA!" just as loud as you possibly can.

Drinking copious quantities of beer can destabilise the frame of reference quite nicely.

You can do the shouting "LALALALALALALA!" just as loud as you possibly can too..it all works for me.

That is the point exactly. It is said, you cannot exceed the speed of light because of Einsteins equations that say light is a constant regardless of reference. The only thing that is constant is the frequency spectrum your eyes can perceive based on the composition of the retina. As with most suppositions, it is incorrect to assume the observer is a driving force of the observed.

This was based on Einsteins supposition that while travelling at the speed of light, you could see your own reflection in a mirror travelling at the same speed. There are a number of inconsistencies here.

First - to see your own reflection, light would be going at the speed of light until it hit your face. Light would re-radiate at speed of light forward, but you are travelling at the speed of light. This would have the same effect as hitting the sound barrier. The light going forward would never reach the mirror. Ask any pilot that has broken the sound barrier. When he exceeds the speed of sound, it gets very quiet. He cannot hear the engines behind him. He can only hear equipment in front of him.

Second - To be able to see your reflection, light would have to travel at 2 X C until it hit the mirror then the Doppler effect would slow it down to C for the return trip. But 2 X C is contrary to the assumption you cannot exceed the speed of light. In fact a mirror travelling at the speed of light and facing backward would not reflect any light. (appear pure black)

They also say the while travelling near the speed of light; the distance covered by calculation is greater then the speed of light, yet you do not exceed the speed of light. This is because of time dilation which is in fact moving (stretching) your position in space. The fact is that when you put an error in the calculations, it requires a counter calculation to make all things balance. In other words the error on both sides of the equations balance. In fact it is the mathematics here that is stretched.

So far I have seen no proof you cannot travel faster then the speed of light. Evidence of physics suggests that it would appear much the same breaking the sound barrier. The problem is the amount of energy you need. The faster you go through a liquid the more it seems like a solid. The faster through a gas, the more it seems like a liquid, and faster yet and it seems like a solid. One could extrapolate that in space the same effect would hold true. The faster you go and the more objects you collide with, regardless how small, the more resistance will be felt.

If you travelled faster then the speed of light, and then slowed down and looked behind you; you would see yourself arriving. Since you can only see a specific frequency spectrum and because of the Doppler effect on your eyes; at Half the speed of light you would be able to see frequencies at half the visible spectrum you see now. The closer you go to the speed of light, you would eventually be able to see sound. While travelling faster then the speed of light you would not be able to see. Unless there are other objects travelling faster than light.

I see you've been studying Frankenstein's equations again!

Yah... Got bored.. The old brain needs exercise once in a while, and other times it's just fun to stir the pot

Speed of light is not the fastest thing in the universe. And let me hypothesize here that just saying that if you would shot a bullet and I could fly like superman and reach out and catch it and bring it back my way. That would make me faster than a bullet. Alright say if I had the ability if you turned on a vary bright or strong light either way and traveled so fast as to catch the end of that light and brought it back with me so as it will never be seen again by anything or one at the direction it had been traveling. What would I be faster, stronger or what. There are more, one that I've never even heard anyone compare it to being faster. And probably more that we will discover in our future. Just like we could never fly nor could we ever break the sound barrier, go to space and the moon. But eventually all of that has been overcome even with all the critics. So I'm optimistic that some where some how sooner or later we will find a way to do almost every thing that we want. And the point is we always have got to keep reaching for the stars. And just because right now most people only believe that Einstein's theory that light is the fastest is no reason to not believe that something else is faster. And now case in point is if Two objects were backed up to each other and they both would go as fast as they could in their own opposite directions and the one that went the fastest would be the "WINNER" would it not? So if you do the same experiment over again and if one went so fast that it had sucked the other opponent backwards with so much force that it could not escape! And I believe that I'm going to hear so many theories on the different factors that come into play and probably even try to say you cant compare the two like that. But since we at this time have no substantial information about the whole physics of a "BLACK HOLE" I'm probably stay with my theory that the speed limit that a Black Hole must travel into its self or where ever. To suck complete planets and galaxies and YES even "LIGHT" cant travel fast enough to escape the velocity of the hole. The BLACK HOLE get my record for being the fastest. And if someone does come up with a good reason why they fell the two doesn't compare. Then also show why. Thank You!

Well, that was an interesting bit of ignorance. Not only do you use incorrect terms, but you contradict yourself, as well.

I had just came the this site today and the theory of breaking the speed of light is something I believe in vary much that is possible. And I have always believed that the (-) speed of a BLACK HOLE is and always greater than the (+) speed of light. And as I said if you have a real reason that you can explain, Is to do so and not sit on your keister and say something is wrong if you cant show it in principle. Or if we are not talking about any thing that is faster than light in this conversation please excuse me for being in the wrong place. And if I must have contradicted myself some where. As I sad before not to just sit back on that keister and tell me that I had contradicted myself because a person most generally does not initially do that. Show me where and if I have then I'm sorry for that mistake. So unless you are capable of explaining this. everything you have just said means nothing to me. For I'm under the impression that this is a discussion and learning forum. And the only thing that I have learned from your opinion is nothing except that you have some type of opinion. And I never had liked typing nor will. But I do not like giving the short answer and be misunderstood. And for another reason is that when most people are firmly set in their beliefs and hears some one contradicting what they were raised to believe in generally will not listen past the point that they may be wrong. And I felt that if I had not gotten their attention about how things could out race each other or how some things are in their way faster than the other. Then it would be no use in trying to change some peoples ideas that a BLACK HOLE is faster than LIGHT it self. Now if I have contradicted myself again please show me or don't bother your self in just saying you have an opinion. Which everyone one does. Thank You!

OK. The main thing is first you just sort of ramble about imagining being faster than light. Then, you talk about about the "negative speed" of a black hole... What the heck is that???

A mathematical entity. If you exceed the speed of light, you go back in time, but with Negative Speed you go forward in time. As simple as that.

Black Hole is where you do it.

Well, not in my living room, that's for sure - I'm all booked-up for the next two months.

- - - -

"You break the speed of light - you pay for it" - Chinese proverb, by Verm L. Prn

It will not help you understand anything if you cant understand it by now. So without all the other metaphor's. I'm just telling you short and sweet that LIGHT cant travel fast enough to escape the speed of a BLACK HOLE. No rambling or anything. Now do you understand a BLACK HOLE is the fastest speed in the universe. I'm so sorry that I had also forgot about the other people out there with a short attention span and are not able to follow a concept all the way thru. If its more than 50 or 60 words. So please except my apologies because I'm truly sorry.

A black hole is not a speed - Gravity is caused by a mass' ability to curve space-time. That's why light bends its path when passing a massive object like a planet, or star, or even a black hole. The more massive the body, the more space-time is curved.

The event-horizon of a black hole is the theoretical point where space-time is curved so much that light does not have a free path back out. Hence, the escape velocity caused by the gravitational force of a black hole (at some point) needs to be faster than the speed of light, and that "traps light." It is not a "negative velocity."

True, also do we both agree that the speed of the gravitational pull down the whirlpool is as far as we know at this time so fast that light itself cant travel fast enough to escape. Like the Apollo had to create enough speed to escape Earths gravitational pull. And right I my have mis-categorize the Black Hole as a neg. speed. But at the time I was trying to come up with an analogy to explain what I was getting at I could have used a different term. But at that time I was looking at it thru my point of view. THANK YOU! BILL

OK, but just so we're on the same page, I think that the concept of "...the speed of the gravitational pull down..." is somewhat misleading.

For example, you talk about the speed that Apollo had to create to escape Earth's gravitational pull - Actually, if you had a craft that had a really powerful and compact fuel source, you could leave the face of the Earth and fly all the way to the Moon at 5 MPH. The concept of "escape velocity" is simply this... Imagine that the only object in the Universe was Earth. If you fire a rocket that can thrust for only a limited amount of time, to send the rocket to an infinite distance, it has to reach approximately 25,000 MPH. At that speed (and after the fuel runs out) a rocket traveling at 25,000 MPH will coast and begin to slow down because of the pull of Earth's gravity. However, if the rocket reached the 25,000 MPH escape velocity, the rocket will finally slow to a stop at infinity. That is the definition of "escape velocity." If you want to calculate the escape velocity for a heavier mass than the Earth (say, the Sun), you'll find that the escape velocity is much higher. This is just mechanics.

Remember that a photon is essentially traveling without propulsion, and has no ability to "boost" its way out of the gravitational field of the black hole. The escape velocity at the event horizon of a black hole is higher than the speed of light... Therefore, if a photon "coasts" past the event horizon, its speed is not fast enough to coast back out.

This is a bit simplified, but is essentially what's going on.

But if I understand any of it, a photon emanating from a black hole, is created at the brim of the event horizon, as a result of matter torn apart falling over (the E.H)

If a gravitational pull decreases with distance, ho severe is it right outside the event horizon ?

Very intense!!! This is realm of Hawking radiation... This is where all the virtual-particles that exist as an opposite pair can get ripped apart. Instead of just coming back together and canceling out, one particle may get trapped in the black hole, while its partner goes flying out into space!!!

The production of the Hawking radiation theoretically balances the loss of mass to the Universe when the star shrinks that causes the black hole. Furthermore, the intensity of Hawking radiation determines when the black hole will completely evaporate in one last explosive blast of Hawking radiation.

Guys, this is all quite fascinating. Whist trying to wrap my head around this I found a brief summary. There is a quote posted by 'zephyr' at the bottom of this page - is it a good description of currently accepted science? Not being well versed in this stuff, I'd value your opinions/comment.

I don't think so... The aether is a rather Newtonian concept, and has been pretty much been beaten to death along with flogistan!

Noo wayy man! Flogistan burns, baby!

Hi Yuval, I think vermin has answered adequately. Just one further comment.

The gravitational 'pull' just outside the event horizon (EH) is coordinate dependent. In Schwarzschild coordinates it is zero (the 'frozen star paradox'), but in the local coordinates of the particles, the gravitational pull grows without limit as they near the EH, where escape velocity equals c.

As I understand Hawking radiation, one of the virtual pair may have an instantaneous local velocity exceeding escape velocity (just outside the EH), while the other may not and will hence fall in.

-J

You said "Well, what the hell was he so pissed off about?! I thought he wanted his creation to do great things."

Basically; as one group, we are capable of doing monumentally stupid things... even to our own destruction. (We call this Mob mentality).

Is there any other kind? With our media, all around the country, the members of the mod are just sitting and waiting in their easy chairs.

Assuming that it's a cone: just under 14 miles in diameter at the base.

OK, now work out the G force at the top of the tower. Crash hat will have to be strong to contain all the squished body parts.

KISS: Throw yourself at the end of a tether rope (2.7 billion miles long)...less material involved...

Lets see Rick,

2.7 billion miles; That's about the distance from Pluto to the Sun at perihelion. Since the earth is nominally 92 million miles from the sun, that puts me at approximately 92 million miles beyond Pluto. I might qualify as the tenth planet (albeit a minor one) right along with Eris, or Quaoar or Sednis (damn! It's cold out here).

It'd be one Helluva ride, though !!!

Oh, and bring your sunglasses...

and should i wear a helmet if i were on top?

You should be wearing a helmet regardless.

Forget the tower. If you travelled to a star one light year away and you travelled at an average speed of twice the speed of light, you would get there in six months. You would have eaten about 180 dinners by the time you got there. If you did the same on the way back, you would have eaten another 180 dinners during a period of another six months. To the people on Earth, however, you took one year to get there and one year to get back according to their clocks. They will have eaten about 720 dinners while you were gone. Physical laws say that speed is equal to distance divided by time. The star is one light year away, but your time according to your clock was running at one half of their clock's speed because you were moving relatively at twice the speed of light. You never missed a single meal and you never broke a single law of physics. When we get into serious space travel, we will have to accept that we might be younger than our greatgrandchildren when we get back to Earth.

Or find them waiting for us, because in the interim time, they discovered a much faster and efficient way to travel.

Hi Guest, nice try, but you got your relativity just slightly wrong. The dinners could however work out the way you described.

To achieve a relativistic time dilation factor of 0.5 (your clock running at half the rate of Earth clocks), you need a relative speed of only √[1-0.5²] c = 0.866c, not 2c (which is unphysical).

What you did is to divide the Earth's measured distance to the star by your own recorded time for the travel, which is an invalid way of calculating speed. Distance and time measurements are reference frame dependent things.

Regards

Has'nt it been tried before Genesis 11:4.

You're priceless, vermin.

Hmm, I'll give you three sound barriers and a plank length...

I appreciate your forum contribution, Jorrie. It is discussions like this that improve our comprehension of the world around us. I believe we have the technology today to accomplish space travel at multiples of the speed of light in the sense that we are not really exceeding the speed of light but are diminishing the time it takes to get someplace far away. The concept of time being different in different parts of space is not easy to grasp. The only measured indication I've seen that a time shift occurred was when the Galileo spacecraft exited our solar system. Physicists attributed the anomaly to some unknown force affecting the motion of the spacecraft. I believe the atomic clock and radio equipment on board Galileo are running at a faster speed than an equivalent clock and radio equipment on Earth. However, if we took the Earth clock to where Galileo is, we would find that the two clocks are running at identical speeds and the receivers and transmitters are still on the same frequencies. The Doppler effect has already been taken into account. The anomaly is more likely, in my mind, to be caused by Galileo being more distant from the center of mass of our solar syatem.

Hi guest, you are welcome.

You wrote: "The concept of time being different in different parts of space is not easy to grasp. The only measured indication I've seen that a time shift occurred was when the Galileo spacecraft exited our solar system."

I think you are referring to the two Pioneer spacecraft and the 'Pioneer anomaly'.^[1] Galileo never left the solar system, but was commanded to crash into Jupiter when its fuel ran out.

The Pioneer anomaly has to do with a 'mysterious force' acting on the two identical spacecraft, which probably has to do with their particular nuclear power plants. It has not been observed on any other spacecraft.

You are right that clock differences do happen between Earth clocks and spacecraft clocks. This depends on their relative velocities and on the positions relative to the Sun. The faster, the slower the clock and the farther from the Sun the faster the clock. It is called velocity and gravitational time dilation respectively.^[2]

These are accounted for and are not part of the 'Pioneer anomaly'.

Jorrie

[1] http://en.wikipedia.org/wiki/Pioneer_anomaly

[2] http://www.relativity4engineers.com

Jorrie,

Did you read the article about the galactic bow shock that occurs as or galaxy travels in a direction perpendicular to the galactic poles? Seems that our solar system orbits the poles of the galaxy in a sort of bobbing motion that takes us out to the galactic bow shock about once every 60 million years. SCRAPE!!!

Hi vermin, no I did not read it. Have you got a link/reference?

I'm wondering how they know about a galactic bow shock? Pure speculation, or what?

Hey man they stood on the rail and looked over like whats 'er name in Titanic innit ?

Your link, squire.

Hi vermin, tx.

That Space.com article is quite confusing to me, e.g. "Our solar system has a shock wave around it, and it produces a good quantity of the cosmic rays that hit the Earth. Why shouldn't the galaxy have a shock wave, too?" Melott said."

AFAIK, bow shocks do not produce cosmic rays, they actually remove energy from the interstellar or intergalactic wind, slowing the particles (mostly protons) down to subsonic speed relative to the surrounding gas. They are produced in all galaxies, but apparently the ones coming from outside of the Milky Way are more energetic than those produces within.

What does make sense is that our galactic magnetic field is stronger inside the disk than outside it and that it shields us better when we are inside the disk than when outside, especially on the side facing Virgo (the 64 million year cycle).

But, what has the galactic bow shock, if it exists, got to do with it? We never go 'outside' of it!

Jorrie

I think the article is trying to say that we enter a region where we're less protected than if we just stayed where we were. Also Pioneer may be experiencing a similar sort of bow shock when leaving the Solar System.

Star Trek theorised that leaving our galaxy, we would encounter an energy field that would make certain humans turn into psychopathic telapaths. Perhaps the force exerted on Pioneer is the interface between the Sun's bow shock and what which lies beyond.

Just an idea.

Hi Jorrie and vermin,

"As far as we can tell, though, time is a one-way process; it never reverses, even though no laws restrict it."

"It's quite mysterious why we have such an obvious arrow of time," says Seth Lloyd, a quantum mechanical engineer at MIT. (When I ask him what time it is, he answers, "Beats me. Are we done?") " [Excerpted from an article in Discover magazine]

What do you guys think about this? Somehow this arrow of time must be interconnected with the speed of light. Seems like.

-John

First, techno...

OK, so you're in a speed boat and you shoot a cannon in a direction directly ahead of you. Our day-to-day math says the cannon shell's speed is shell speed + boat speed. And we would be basically correct. Unfortunately, this doesn't work with light. If you are near the speed of light, and shine a flashlight ahead of you, the light will move forward at exactly the speed of light. Relativity doesn't allow you to add speeds like that.

I don't know whether you'll accept this a proof of the speed-limit, but many years ago, they ran into the problem of increasing the speed of electrons in cathode ray tubes. They added way more than enough energy to theoretically make the electrons go way faster than the speed of light, but they couldn't even get them anywhere near the speed of light. They did, however, greatly increase in mass, which was easy to measure at the end of the tube. Bang!!!

Johnjohn,

That's always bugged me, too. We can move all over the place in space, but seem to be along for the ride as far as time is concerned. Perhaps we travel in all directions in time, but all we can experience is the length of the path and not its direction. Perhaps if our brains were wired differently, our position and direction in time might become apparent.

If you would like to try an experiment along these lines, I still have my Fisher-Price Little Handyman's Kit. I'll start digging and you can tell me when the clocks start to change. What do ya say?

Maybe there are lots of universes in which time is not constrained to proceed in one sense of direction. But, in these universes no structure can ever develop because as numerous science fiction writers have pointed out any entity which can travel backwards in time inevitably destroys itself (before it starts to exist).

I was just thinking what might be slowing down the two Pioneers is leaving the Solar System and heading into that which our own bow shock protects us from.

Just a thought

Jorrie,

I think my post #42 has merit, what say we apply for a grant.

Of course, we'll have to hold auditions for who can yell the loudest. Sounds like a good use of a weekend!

Consider this possibility: Imagine carrying a flashlight into an infinite elevator having a mirror on the ceiling. Imagine accelerating at 1.5 G until we leave our galaxy. From time to time we shine the flashlight toward the mirror and measure the transition time to the ceiling and back. It will always be the speed of light as we know it. Then decelerate to 1.0 G and continue to perform the light speed measurement. Eventually the motion of the elevator will reach the speed of light, and our flashlight measurement is unchanged. We know that we are continuing to accelerate beyond the speed of light because we continue to feel the force of 1 G on our bodies. Yet our mass is not changing because we are not getting any heavier, and our measurement of light speed is unchanged. What is happening?

Perhaps we have experienced a shift in time in our elevator relative to the time experienced by those still on Earth. Those people who accelerated the electrons theoretically beyond the speed of light could have verified that the electrons did not exceed the speed of light. The apparent increase in mass as measured by collision energy absorbed at the target can better be explained as electron collision energy resulting from a longer time experienced by the electron stream relative to the time experienced by the observers. The mathematics should work out when the time shift is taken into consideration.

"LALALALALALALALALALALALALALALALALALALALALALALALALALALALALALALALALALA"

Sounds good! I had no idea you could yodel.

By the way, what the heck are you drinking there?! You look the way I did when I used to do MEK shots!

Light beer!

Oh. Does it make you go faster than...

No, but I can do LALALALALALALA in six octaves!

The Vienna Boys Choir wants you!

They'll have to get in line. This group asked me first.

Hi Guest, you wrote: "Imagine accelerating at 1.5 G until we leave our galaxy. From time to time we shine the flashlight toward the mirror and measure the transition time to the ceiling and back. It will always be the speed of light as we know it."

One must be careful in applying the constancy of the speed of light to an accelerated reference frame, like your elevator. The speed of light is only perfectly constant and isotropic for un-accelerated (i.e. inertial) observers in free space.

Your measurement of the round trip travel time of light will be different for different levels of acceleration. Just like it will be different for horizontal and vertical measurements here on Earth.

Jorrie

Consider that, at 1.0 G acceleration, the time up to the ceiling will take a little longer, and the time reflected down will be a little shorter. Those minute time differences should cancel and remain the same regardless of the velocity of the elevator relative to external objects such as the Earth we left behind. Otherwise, if the elevator was travelling at the speed of light minus 1 meter per second and I pulsed the flashlight, I should see a blob of light slowly creep up to the mirror on the ceiling and vanish at relatively nearly twice the speed of light back to my flashlight.

Keep in mind that most of my ideas and proposals are speculation. Conversations with knowledgable people such as you, are very helpful to me. Thank you for reminding me about the acceleration effect on the flashlight beam.

Jorie,

Can you elaborate on accelerated reference-frames a bit more?

Hi vermin, you asked: "Can you elaborate on accelerated reference-frames a bit more?"

The explanation of this phenomenon is easy and very difficult at the same time. The tough part to get one's head around is that a rigid body, uniformly accelerated along its length, suffers different accelerations at its front and rear ends, as locally measured by accelerometers. The front accelerometer will show a smaller value than the rear accelerometer.

One way to 'prove' this is to say that the equivalence between acceleration and gravity demands it. To prove this rigorously is quite difficult, although it has been done.^[1] Various experiments have also demonstrated this behavior of rigid bodies – not directly, but by implication due the the cumulative results of different many tests.

So, if you accept the above equivalence as valid, the rest is easy. It has been proven many times that light gets delayed when it goes deeper into a gravitational field, exactly as predicted by general relativity. It was first calculated by Irvin Shapiro and later experimentally verified on a solar system scale by him and his team. Hence the effect is called the Shapiro time delay of light.^[2]

Let's do simple thought experiment. Put a light source and timing device precisely halfway (as measured by accurate measuring rods) up a very high tower on Earth. Install two mirrors, one at the base and one at the top of the tower. Accurately time the two-way travel time of a light flash to each mirror and back to the middle. We will find that light takes longer to travel to the bottom mirror and back than to the top mirror and back.

This is Shapiro time delay at work. The deeper into Earth's gravitational 'well' it goes, the slower light seems to propagate, if measured over a relatively large vertical distances. However, observers at the bottom and the top would both get c if they measure the speed of light over very small distances. This is because their clocks run at different rates due to gravitational time dilation.

The 'upward' test is precisely equivalent to Guest's accelerated elevator (post #56), with the mirror up front and the light source and timer at the back. The light moves into an area of smaller acceleration as it goes to the front of the elevator. The result would depend on the level of acceleration, as predicted by relativity.

If exactly the same tower was built in free space, with no acceleration or gravitational fields and the same experiment was performed, the two-way time in both directions would have been the same - close to the geometric mean of the two Earth timings.

Hope this helps a tiny bit. I expect it will generate more questions than supplying answers, but let's be bold and tackle this thing head-on.

Jorrie

[1] arXiv:physics/9810017 v3 13 Apr 1999, H.Nicolic, "Relativistic contraction of an accelerated rod".

[2] Tests of Relativity page from Relativity 4 Engineers.

Hi Jorrie,

you said: "Put a light source and timing device precisely halfway (as measured by accurate measuring rods) up a very high tower on Earth. Install two mirrors, one at the base and one at the top of the tower. Accurately time the two-way travel time of a light flash to each mirror and back to the middle. We will find that light takes longer to travel to the bottom mirror and back than to the top mirror and back".

I'm a little confused about the experiment. Am I wrong in asuming that there is a mirror somewhere off in the distance for the light source at the middle of the tower to bounce the light back to the mirrors at the base and top of the tower?

Otherwise, a most informative post. Thanks.

-John

Hi Johnjohn, you asked: "... a mirror somewhere off in the distance for the light source at the middle of the tower to bounce the light back to the mirrors at the base and top of the tower?"

No, the simplest scheme is to send a flash of light from the central source straight to the mirrors at the top and at the base of the tower. Measure how long it takes for the reflections to come back to the center for the top and the bottom mirrors respectively.

Practically very difficult to perform as described with any accuracy, but then, this is a thought experiment...

Jorrie

PS: The 'upward' test should appear to live up to the title of this thread - it will apparently be 'breaking the speed of light'!

Got it! Now it makes sense.

Thanks

Thank you, Jorrie, for your statement, "This is because their clocks run at different rates due to gravitational time dilation." The concept of clocks running at different rates depending on gravitational time dilation might help to explain some observed oddities such as quasars. It may be that quasars are actually stars in our own galaxy that happen to be in areas where there is relatively little mass and consequently little time dilation/compression. They exhibit an extreme red shift to us, perhaps not due to doppler motion but because of their clock rate difference. The brightness of those objects may actually be due to their being much closer to us rather than at the extreme limit of our observable universe. If we went to those objects, we might find that the red shift lessens as we enter the area of low gravity where they are. Then, if we look back at our own sun, we might see that our sun spectrum has shifted toward the violet end of the spectrum.

Unfortunately, they have been proven to be distant objects. One of the early mysteries about quasars was that they seemed to occur in pairs or four of a kind. It wasn't until much later that someone figured out that their "pair-nature" wa caused by distant galaxies between us and the quasars, which were acting as gravitational lenses, splitting the quasar's light into two or more identical images.

If I remember correctly, the reason why they freaked so many astronomers and physicists out, was that, in fact, they were originally considered relatively close stars. Being viewed as local, there were changes occurring and energies being released such that the theory of Relativity could not account for their behavior. Once their true distance was realized, things started to make more sense.