[Prof. Templeton]

The speed of light is approximately 300,000 kilometers per second. The radius of the sun is about 700,000 kilometers. It takes about 8 minutes for a photon to travels from the surface of the sun to Earth. If a photon is created halfway between the center of the sun and it's surface, about how long would it take the photon to reach the Earth?

[Yoruichi-san]

Uh...

It will never reach earth...depends on the trajectory of the photon, but the probability of the photon being on a direct trajectory towards earth is really small...too lazy to do the calculations to figure out the exact numbers though...

Edit: Love your sig by the way ;P

Edited September 7, 2008 by Yoruichi-san

[Guest]

About an extra .857 seconds than it would if it was created at the surface of the sun.

[Prime]

Does photon travel with the speed of light through the sun's core? Can it get to the surface at all? I was brought up to believe that light does not travel through non-transparent obstacles.

[Prof. Templeton]

Uh...

It will never reach earth...depends on the trajectory of the photon, but the probability of the photon being on a direct trajectory towards earth is really small...too lazy to do the calculations to figure out the exact numbers though...

Let's say the photon's initial trajectory is directly toward earth.

Does photon travel with the speed of light through the sun's core? Can it get to the surface at all? I was brought up to believe that light does not travel through non-transparent obstacles.

Are all the photons coming from the sun generated on the surface? What about X-rays?

[Guest]

an extra 1.16 seconds - unless theres some obvious thing like "roosters dont lay eggs" that im missing

[Prime]

It would take photon zero time to reach Earth. Time stands still for the objects traveling at the speed of light.

[Guest]

It would take photon zero time to reach Earth. Time stands still for the objects traveling at the speed of light.

So the speed of light is instant

[Guest]

350,000 k (1/2 the radius) divided by 300,000 = 1.16666 seconds to travel from the halfway point to the surface + 8 minutes to earth = 8min 1.16666666 seconds

[Guest]

well I'm gonna say 5000 to 8500 (years) I don't think the equation is certain yet

[Prof. Templeton]

well I'm gonna say 5000 to 8500 (years) I don't think the equation is certain yet

Thats more like it! The point I'm getting at is, even though photons travel at the speed of light, they will bounce around inside the sun, and may take up to half a million years to reach the surface and then eight minutes to reach the Earth. All the figures in the OP were diversionary. Likewise a single electron may take several hours to travel through a ten foot copper wire. Good thinking LIS (Lost In the Sun).

[Guest]

Thats more like it! The point I'm getting at is, even though photons travel at the speed of light, they will bounce around inside the sun, and may take up to half a million years to reach the surface and then eight minutes to reach the Earth. All the figures in the OP were diversionary. Likewise a single electron may take several hours to travel through a ten foot copper wire. Good thinking LIS (Lost In the Sun).

Since this forum is for brain teasers, readers should expect that the answer can be determined with the information given in the riddle and everyday common knowledge. Questions that require specialized knowledge such as this one belong in "Others". In a brain teaser book for example, one would not expect the answer to have the specialized knowledge this one requires and would expect the answer to be similar to the one Scraff posted. Since this has already been answered, I'll just leave it here. This post is just FYI for future reference.

[Prime]

So the speed of light is instant

The speed of light is about 300000 km/sec to an observer. However, when object travels at the speed of light, time does not elapse for that object. (As far as that object is concerned, it got from here to there in no time at all.) So I stand by my answer: zero time elapses for the traveling photon.

[Guest]

The speed of light is about 300000 km/sec to an observer. However, when object travels at the speed of light, time does not elapse for that object. (As far as that object is concerned, it got from here to there in no time at all.) So I stand by my answer: zero time elapses for the traveling photon.

tired and weary - I'll stick my neck out - even if that is perfectly correct, and thousands of years after the photon escaped/reemerged it would travel at a given speed, it will not be instant. Though the photon may 'feel' it has travelled zero time

What do humans see, if they were on as pace ship travelling from the sun to earth in that 8.5 mins? Does there watch not show any movement, are you saying that a photon does not take 8.5 mins.. Maybe I'm doing my usual oversight thing. Anyway it's not an exam question for my masters

[Guest]

So I stand by my answer: zero time elapses for the traveling photon.

The OP was phrased in such a way that this would not be an acceptable answer. If the OP is talking about photons' travel time as experienced by an outside observer when presenting the riddle, we must also present the answer for travel time as experienced by an outside observer. And he of course was:

"It takes about 8 minutes for a photon to travels from the surface of the sun to Earth."

[Prime]

...If the OP is talking about photons' travel time as experienced by an outside observer when presenting the riddle, we must also present the answer for travel time as experienced by an outside observer....

The OP was somewhat ambiguous, while creating all that diversion. And so it may be a fair game. Especially so taking into the account the consecutive posts:

Let's say the photon's initial trajectory is directly toward earth.

Are all the photons coming from the sun generated on the surface? What about X-rays?

Prof. T rejected Yoruichi-san's guess that photon was unlikely to reach the Earth. And yet based the "correct answer" on photon's bouncing around.

Of course, for my answer, the OP would have to worded slightly differently. On the other hand, the "time standing still" for objects moving at the speed of light is more common-knowledge than photon's behavior.

[Guest]

Prof. T rejected Yoruichi-san's guess that photon was unlikely to reach the Earth. And yet based the "correct answer" on photon's bouncing around.

So what? the OP was clarifying that the riddle was meant to have one answer how long it would take for a photon to reach the Earth. That means how long it would take to reach a certain distance or reach the Earth if that were its destination.

That the OP is talking about time in relation to outside observers is evident and it follows that answers about how long something takes to go from point A to B should only be answered the same way. When a riddle maker claims it takes about 8 minutes for a photon to reach the Earth and not that it reaches the Earth instantaneously, it's understood that answers given in time units are to be given with the same constraints.

[Guest]

The answer is infinite. If you look at the question, he is asking if the photon travels from halfway between the center of the sun and it's surface, then it does not mean that the exact location is also between the sun and earth, therefore, you can think of it as another sphere inside the sun that is 350,000 kilometers in radius, and the photon can start from any point off of that internal sphere surface, which means that it can be an infinite number of answers.

[Guest]

The speed of light is about 300000 km/sec to an observer. However, when object travels at the speed of light, time does not elapse for that object. (As far as that object is concerned, it got from here to there in no time at all.) So I stand by my answer: zero time elapses for the traveling photon.

Sorry but this is not correct. The theory of relativity states that time slows down for objects moving at the speed of light, not stops. There are sub atomic particles created in the upper atmosphere with lifespans so small that they shouldn't be able to make the journey by normal calculations. However, since they move at the speed of light, they can reach the surface and farther because time is only relative to the observer. If time stood still for them, they would die out in 0.0 sec. They would never exist. Consider the classic example.

You have 2 spaceships flying at the speed of light parallel to eachother. One is directly above the other, 5 light seconds away. Now the top ship has a lasar pointing straight down, and the bottom ship has a mirror on the top. If the ships fires the laser, and it bounces back, an observer on the top ship, or one moving along side them at the same speed, sees the light travel the distance between the ship x2. The time would be calculated as speed of light * distance between ships * 2. However, to a stationary observer, the light is seen moving diagonally. So to them the distance is sqrt(distance between ships^2 + distance traveled before light returns^2) More complex written than in most visual examples. Point is, a stationary observer sees the light travel a longer distance, therefore, calculates a longer time.

Edited September 8, 2008 by EyesOfTheDead

[Guest]

Sorry but this is not correct. The theory of relativity states that time slows down for objects moving at the speed of light, not stops.

No, he is correct. Time slows down as objects approach the speed of light. If an object could travel the speed of light, time would stop from the perspective of the object. Since photons travel the speed of light, time has stopped.

The Flat Universe and the ageless photon

It would not be possible to judge that a photon of light was splatted flat by looking at it its thickness; this would require that parts of it could be seen by different parts of the eye. Just as the photon is splatted, the speeding photon sees the world along its path without depth. Einstein explained that moving things appear shorter. Just as the moving tourist 'sees' the scenery appear to move past outside a train, then at the ultimate speed, the photon sees all points along its route drawn together. To the photon, its source and its destination are at the same place, superimposed images on a flat page. Another consequence of moving rapidly, said Einstein, is that time seems to slow down to the traveller. For the photon, at the speed of light, time has stopped. From source to destination, the photon does not age; it is at all places on its journey at the same time. This opens up the truly remarkable possibility that the photon can cover as many routes from A to B as it wishes, without wasting time, and so really can take the best aim at a gap. The straight line that light is supposed to take is really only the most likely highway, the one needing the least effort. The narrower the toll gate that it is required to pass through on its way, the more arbitrary a route it can take thereafter.

http://www.oxygraphics.co.uk/photons.htm

Now SR tells us that at the speed of light, time stops, your length contracts to nothing, and your resistance to acceleration becomes infinite requiring infinite energy (as observed by a frame of reference that is not in motion with the system).

http://science.howstuffworks.com/relativity21.htm

Likewise, the rate of the passage of time decreases as the speed of light is approached and at the speed of light time stops!

http://en.allexperts.com/q/Physics-1358/Speed-Light-1.htm

[Guest]

Ist - should this be in others - cos I think this is open discussion ???

2nd - yes the photon starts from anywhere half way in the sun - and does not specify that it is on the side directly next to earth, however it says that this particular photon IS heading in the earths direction after leaving the sun. Therefore it is going to reach the earth, just a matter of time?

Prime, pls stop fogging the issue with codiciles after setting off on the wrong foot, the topic states 'as observed' if it helps take some kudos over your own view of the topic from another perspectrive.

Can we stay on topic pls