Light traveling from the Sun to Earth

It takes about 8 minutes 19 seconds for light to travel from the Sun to Earth. If some of that light could travel at twice the speed of c, how long would it take those photons to reach Earth?

Your question is not well-defined. First define a new set of physics rules where it is possible for photons to travel at 2c.

Originally posted by KazetNagorra
Your question is not well-defined. First define a new set of physics rules where it is possible for photons to travel at 2c.

It wasn't literally possible for Einstein to run alongside a beam of light in one of his thought experiments, and it's not literally possible for light to travel at 2c. It's not necessary to define a new set of physics rules for the purpose of simply examining a thought experiment.

If it takes light about 8 minutes 19 seconds to travel from the Sun to Earth, then how long do you think it would take light traveling at 2c to reach the earth? Not that light can or does travel that fast, but IF it could travel that fast.

Originally posted by lemon lime
If it takes light about 8 minutes 19 seconds to travel from the Sun to Earth, then how long do you think it would take light traveling at 2c to reach the earth? Not that light can or does travel that fast, but IF it could travel that fast.

In Newtonian physics, presumably exactly half that time. I am not sure what effects relativity has because you haven't specified where the clock is. The 8 minutes 19 seconds is presumably a clock stationary relative to the earth.

Originally posted by twhitehead
In Newtonian physics, presumably exactly half that time. I am not sure what effects relativity has because you haven't specified where the clock is. The 8 minutes 19 seconds is presumably a clock stationary relative to the earth.

He said nothing about changing the position of the clock or what kind of clock is used. However, it has been determined that atomic clocks at higher elevations above the earth run at faster speeds, so that could be a factor to consider. Bur common sense tells us that if no other factors are considered, the light should arrive in half the time if it is going twice as fast.

About 4 minutes 9.5 seconds

There is a possibility that the further the light is from the earth the faster it travels.

The Instructor

Originally posted by lemon lime
It wasn't literally possible for Einstein to run alongside a beam of light in one of his thought experiments, and it's not literally possible for light to travel at 2c. It's not necessary to define a new set of physics rules for the purpose of simply examining a thought experiment.

[b]If it takes light about 8 minutes 19 seconds to travel from the ...[text shortened]... earth? Not that light can or does travel that fast, but IF it could travel that fast.[/b]

According to the equations of relativity, if anything traveled fast than c, it would be moving BACKWARDS and NOT forwards in time! (OBVIOUSLY, you can forget what RJHinds just said; he is talking out of his ignorant ass for he understands NOTHING about the fact of relativity )
So I guess the answer to your question might not seem to make a whole lot of sense! This is one reason (but NOT the main reason ) why Einstein said and believed nothing could go over c and, although I would not totally rule out the possibility he could have been wrong, I believe the most rational default assumption should surely be that he is almost certainly right about this until if or when we have a rational reason or pretty good evidence to believe the contrary.

Originally posted by humy
According to the equations of relativity, if anything traveled fast than c, it would be moving BACKWARDS and NOT forwards in time! (OBVIOUSLY, you can forget what RJHinds just said; he is talking out of his ignorant ass for he understands NOTHING about the fact of relativity )
So I guess the answer to your question might not seem to make a whole lot of sense! ...[text shortened]... this until if or when we have a rational reason or pretty good evidence to believe the contrary.

That was the answer I was looking for, but there's another thought experiment I had in mind to follow this one.


Now let's assume an imaginary observer who is able to view the entire universe, and also assume his clock is the constant. In other words, no matter what relative differences in time may be in effect throughout the universe, we are able to view everything happening (through this observer) in 'real time' according to this observers clock. The observer is able to view everything as it happens (with no delay) and the order of events in the universe can be assigned in order of time according to this observers clock.

So with that in mind, this observer is now watching a science experiment where a person on one planet will push a button sending a signal that has been artificially pushed beyond the speed limit (c) to another planet, to see if the signal will arrive before it was sent. This is something that has actually been tried (with no success) but I'm going to assume this imaginary experiment works and can prove a backwards jump through time. I'm also assuming the distance between the two planets is great enough to make this kind of measurement possible and conclusive.

I could go into more detail, like controls to insure the equipment receiving the signal is precisely synchronized with the equipment sending the signal, but I don't want to overcomplicate this and turn a simple thought experiment into a discussion of what is actually possible or not. There is a point I'll eventually get to, but I necessarily need to set this up first before getting there.

So now we have someone holding his finger over a button that sends the signal. Controls are in place to make sure we can know if the signal arrived before the button was pushed, and the decision to push the button rests entirely with a person who will decide exactly when he will push that button. It's understood he will have a limited time frame to make that decision, say 2 or 3 minutes, and the distance between planets in terms of light speed is about an hour.

But here's where I see a possible paradox. The decision of when the button is pushed rests entirely with the sender. It's assumed he will push that button and send the signal within the time frame he agreed to. But he's been sitting there for hours waiting to do this and drinking cup after cup of Starburst coffee (much stronger than Starbucks) so he leaves his post to relieve himself and misses the launch time. This is something I can personally relate to, but this isn't about me soooooo I'll get to my point...

>>>o===================> [ . ]


If the decision as to exactly when (or even if) the button is pushed is a free will decision, and a signal can arrive before it was sent, then how can the Universe know exactly when that free will decision was made before it happened?

Originally posted by humy
According to the equations of relativity, if anything traveled fast than c, it would be moving BACKWARDS and NOT forwards in time! (OBVIOUSLY, you can forget what RJHinds just said; he is talking out of his ignorant ass for he understands NOTHING about the fact of relativity )
So I guess the answer to your question might not seem to make a whole lot of sense! ...[text shortened]... this until if or when we have a rational reason or pretty good evidence to believe the contrary.

That answer does not make a whole lot of sense, in fact, it defies common sense. Try again.

The Instructor

Originally posted by RJHinds
He said nothing about changing the position of the clock or what kind of clock is used. However, it has been determined that atomic clocks at higher elevations above the earth run at faster speeds, so that could be a factor to consider. Bur common sense tells us that if no other factors are considered, the light should arrive in half the time if it is goin ...[text shortened]... ossibility that the further the light is from the earth the faster it travels.

The Instructor

Common sense also tells me the half way point between 8 minutes 19 seconds and instantaneous would have to be 4 minutes 9.5 seconds, but I agree with Einstein that a speed limitation exists. I don't know how he determined light to be the top speed and a point where time itself stops, but so far as I know no one has proven him wrong.

There were a few things that were too bizarre for even Einstein to consider. He came up with what he called "a spooky influence from a distance" and then rejected the idea. As it turned out he was right even though he thought he was wrong. LOL It's like the guy had two completely independent brains, one brain was able to figure things out and the other brain thought it was too bizarre to be true. This actually makes sense though... it's fun to occasionally visit outside the box but I wouldn't want to live there. That's where all the crazies hang out. LOL

Anyway, I believe there are effects (gravity being one) that are caused by the action of mass and are able to affect mass, but in and of themselves are massless. This is a tricky point, and many people either disagree with me or don't seem to understand my position, but I still think it's something worth considering. In a nutshell, I'm saying the existence of an effect is dependent on mass but is not comprised of energy or mass. This is why gravity doesn't need to travel in waves at or near the speed of light, because there is nothing actually there to be traveling, and so a speed limitation doesn't apply. And I think time and gravity are more closely related than simply one having an effect on the other. Time and space are both defined by mass (defined by what mass is and what mass does) but time and space in and of themselves are massless... neither one can exist without mass, and both are defined by mass, but time and space in and of themselves are massless.




pssst, just between you and me... I'm going to catch some flak for saying this, just watch and see. It never fails

Originally posted by lemon lime
That was the answer I was looking for, but there's another thought experiment I had in mind to follow this one.


Now let's assume an imaginary observer who is able to view the entire universe, and also assume his clock is the constant. In other words, no matter what relative differences in time may be in effect throughout the universe, we are able to ...[text shortened]... erse know exactly when that free will decision was made before it happened?

"... then how can the Universe know exactly when that free will decision was made before it happened?"

An unexplained form of omniscience, it would seem.

Originally posted by lemon lime
Common sense also tells me the half way point between 8 minutes 19 seconds and instantaneous would have to be 4 minutes 9.5 seconds, but I agree with Einstein that a speed limitation exists. I don't know how he determined light to be the top speed and a point where time itself stops, but so far as I know no one has proven him wrong.

There were a few th ...[text shortened]... 'm going to catch some flak for saying this, just watch and see. It never fails[/i]

Does this have anything to do with the idea of time travel?

The Instructor

Originally posted by RJHinds
Does this have anything to do with the idea of time travel?

The Instructor

It does have something to do with time travel, but only in the sense that (IMO) there are too many paradoxes to overcome. Time travel may intuitively seem possible because we can imagine it happening, but I don't believe it's something we can actually do. This hasn't dampened my enjoyment of time travel stories or thinking about it from time to time... I still enjoy watching sci-fi flicks involving time travel, even though I no longer believe it's possible.

At one time I thought I had overcome the grandfather paradox (i.e. what happens if you go back in time to kill your grandfather, before he fathers your father?) by suggesting the attempted assassintion didn't work, and this is a foregone conclusion supported by the fact that you exist... you couldn't exist to kill someone who made it possible for you to exist if he didn't already father your father who fathered you. So in other words, even if you did manage to go back in time with the intent of killing your grandfather (while he was still a boy) you can know for certain beforehand (before making the trip back in time) that it was a failed attempt... you either couldn't find him, or you overshot the time and place target, or your futuristic laser gun didn't work because you forgot to recharge it before you got there, or for some other reason you weren't able to accomplish your crazy-ass suicide mission. So anyway, long before your father was born you had already been there and failed in your attmept to kill your own grandfather.


Why is it some scientists seem to come up with the most vile and gross examples to illustrate what they are talking about? I mean really, what's up with Schrodinger killing his cat? What's that all about?

Originally posted by Grampy Bobby
"... then how can the Universe know exactly when that free will decision was made before it happened?"

An unexplained form of omniscience, it would seem.

Or maybe... what appears to be a short jump back in time could in fact only be an illusion. If so, then this one would be a whopper.

We can know that cause and effect still occur in natural order, with cause coming first and then effect. But that's pretty much all we can know. Because no matter how careful we are or what controls we put into place we can't actually confirm (know without a doubt) that the signal arrived before it was sent, even though everything we look at is telling us it happened that way. I can't even say for certain if my all seeing in real time with no delay imaginary observer is able to view the event the way I think it may have really happened, with the button first being pushed and then the signal being received, but this imaginary observer is probably in the best position to see how it all really happened. Too bad he is only imaginary...

And for all I know he might not even be a he, he might be a she... or both!!! I've been sitting at this computer too long today and it's starting to take its toll... my brains are so shot right now I don't even know much about my own imaginary observer!!! I mean, who exactly is this observer, this cosmic peeping tom, and where did it come from... if it came from my mind then how do I get it back in there? Does it really need to go back in? What do I need it for, it never did anything for me... and how can I be sure it's really mine? Is their a DNA test for something like this? What will I see when I wake up tomorrow and look at this... what will I see that I'm not seeing now?

Someone wake me up when the aliens get here, I don't want to miss that.

Originally posted by RJHinds
That answer does not make a whole lot of sense, in fact, it defies common sense. Try again.

The Instructor

WOW you are just such an ignorant moron. Just for once, try actually UNDERSTANDING something about the topic of conversation for just a change and then come back to us.

Originally posted by humy
According to the equations of relativity, if anything traveled fast than c, it would be moving BACKWARDS and NOT forwards in time!

Would this be backwards in time for a clock on earth, or only for the clock travelling with the photon?