How long does it take for a single photon to travel from the sun?

[AGarvin]

Brian,

Try here.

Andrew.

[renormalised (Carl)]

Originally Posted by Brian W

Moderator, I think this generally fits into this discussion so here goes; It has been decades since my high school math. Could anyone here point me towards on line resources that will enable me to upgrade my math skills so I can at least follow the above discussion? Has to be online as there are no bookstores nor universities near me.
Brian

Brian, try this site. I use it as part of my Masters course to refresh my maths skills....

http://www.mathcentre.ac.uk/students.php/mathematics/

[White Rabbit]

I used the Mathcentre when I did my UNI prep course a few years back. Their work sheets are really good.

Thanks for the replies but I have a few questions.

When you say"It's a photon....it doesn't experience any time at all, since it's traveling at the speed of light." do you mean this in the sense that because it is a photon it can not experience anything because it is not conscious?

[renormalised (Carl)]

Originally Posted by White Rabbit

I used the Mathcentre when I did my UNI prep course a few years back. Their work sheets are really good.

Thanks for the replies but I have a few questions.

When you say"It's a photon....it doesn't experience any time at all, since it's traveling at the speed of light." do you mean this in the sense that because it is a photon it can not experience anything because it is not conscious?

No, nothing like that (although who's to say what a photon thinks). A photon doesn't experience any time because the amount of time dilation that occurs at the speed of light is infinite (which means there's something wrong with the theory....infinities are a curse, but more on that later). Time effectively stands still for the photon, so everything it perceives is NOW. A photon leaving M31 now, would in its world view, have already arrived here.

But for us it's a 2.5 million year long ride

[White Rabbit]

Ah, I understand and it makes sense that when traveling at the speed of light the time dilation would be infinite.

I wasnt sure if you were trying to be funny in your earlier post, lol.

Here is another questions.

If it is impossible to travel at the speed of light due to the fact that your mass increases infinitely and the energy needed to propel you at that speed is infinite. How come a photon can? Is it to do with the Wave V's particle nature of a photon that it is able to travel so fast?

Also read somewhere that you shouldn't think of a photon as a particle only a wave.

[White Rabbit]

Yeah, I took chemistry and Biology in school not physics.

[White Rabbit]

Just found this, I'll listen to it tonight it may just have the answers I'm looking for.

http://www.astronomycast.com/physics...ticle-duality/

[Jeff]

Enjoyed this article (The Life of a Photon):
http://www.propermotion.com/jwreed/E...A%20Photon.htm

Cheers,
Jeff

[sjastro]

Originally Posted by White Rabbit

Here is another questions.

If it is impossible to travel at the speed of light due to the fact that your mass increases infinitely and the energy needed to propel you at that speed is infinite. How come a photon can? Is it to do with the Wave V's particle nature of a photon that it is able to travel so fast?

Also read somewhere that you shouldn't think of a photon as a particle only a wave.

From a Quantum Mechanical viewpoint photons are the fundamental particles for electromagnetic radiation, so in fact light is composed of photons. Photons have a zero rest mass hence can be accelerated up to the speed of light.

Regards

Steven
http://users.westconnect.com.au/~sjastro/small

[renormalised (Carl)]

If it is impossible to travel at the speed of light due to the fact that your mass increases infinitely and the energy needed to propel you at that speed is infinite. How come a photon can? Is it to do with the Wave V's particle nature of a photon that it is able to travel so fast?

Also read somewhere that you shouldn't think of a photon as a particle only a wave.

As has been mentioned, a photon has zero rest mass and therefore can be accelerated to lightspeed.

Photons are both waves and particles....simultaneously. However, they'll act as either depending on the situation they find themselves in.

[renormalised (Carl)]

Here's something for all of you to think about... there's something seriously wrong with Special Relativity and it should be rather obvious.

Hint....think about the final outcomes of the equations.

[skwinty (Steve)]

Originally Posted by renormalised

Here's something for all of you to think about... there's something seriously wrong with Special Relativity and it should be rather obvious.

Hint....think about the final outcomes of the equations.

Wow, what a sweeping statement!
If there is something seriously wrong with SRT then Hubbles work must be discarded as he used SRT to determine velocities in all his expanding universe calculations.
As far as what the photon experiences wrt to time and what we see the photon experience wrt time, the point of different inertial frames needs to be considered.

In any event the "obviousness of this flaw" may be a reflection of our lack of understanding. I agree that SRT may not be complete but I cannot agree that it is obviously wrong.(As you can see from the icon, I am an Einstein fan)

[renormalised (Carl)]

Originally Posted by skwinty

Wow, what a sweeping statement!
If there is something seriously wrong with SRT then Hubbles work must be discarded as he used SRT to determine velocities in all his expanding universe calculations.
As far as what the photon experiences wrt to time and what we see the photon experience wrt time, the point of different inertial frames needs to be considered.

In any event the "obviousness of this flaw" may be a reflection of our lack of understanding. I agree that SRT may not be complete but I cannot agree that it is obviously wrong.(As you can see from the icon, I am an Einstein fan)

That's what's wrong with most people and many scientist.... you seems to think that Einstein is the be all and end all of physics (science almost). He is FAR from it. Considering that he spent most of his career trying to get his head around quantum physics (and rather unsuccessfully at that), he didn't do so well in the end. His whole fame is based on two incomplete theories.

Anyway, here's the problem. Any theory which introduces infinities into its equations, either as part of the workings or as a solution, is meaningless and incorrect in its assumptions. Even Einstein himself knew that, yet just because the rest of the workings seems OK, they persist with the theory in its entirety. Doesn't matter that it can work out masses and lifetimes of objects traveling at substantial fractions of lightspeed, the fact that at lightspeed an object with mass becomes infinitely heavy and zero in size is nonsensical. It's also one of the reasons why relativity breaks down at the singularity in black holes. Precisely because of its characteristics. The results of the equations become nonsensical. Essentially, you get infinities and undefined answers.

Think about it, what do you get when size becomes zero and mass infinite.... a singularity, and if something became infinitely dense and massive, what do you think would happen to the rest of the Universe, regardless of any event horizon?? Yes, a black hole is extremely dense and the gravitational gradient is extremely steep, but it's not infinite. A 10Ms black hole is just that...10Ms, not infinitely massive as you would be led to expect. Something else other than a (true) singularity must reside at the centre of a black hole. It will probably be upto some branch of Quantum Theory to resolve that question.

That's the problem...people don't think. They just blindly accept what's told to them as being gospel and infallibly correct.

It's the same with any theory....Quantum Theories abound with cases where infinities crop up in seemingly elegant equations. The theories then fall to pieces. However, in order to try and preserve face in so far as the theories stand, they use a technique called renormalisation. To put it in simple terms, they add a fudge factor to make the infinities magically disappear. It's usually a long and complicated mathematical abstraction just as complicated as the original equations, but sometimes it can be a simple term, added to counterbalance the infinity. Renormalisation has become the "de rigeur" way of making one's theories seem palatable.

SR maybe elegant, but only upto a point. There's a lot yet to be done before it can be said for certain that it's a complete and totally correct theory. It may never be, and I'd venture to say it won't because I can't see what can be done to overcome the infinities in it's equations. It will probably have to be rewritten in order to become 100% viable. The same goes for GR, but it's less fraught with problems than SR.

My guess is that you'll see some sort of hybrid quantum theory take their place....that will have elements of both classical SR and GR in the theory as part of it's overall structure.

[Brian W (Brian)]

Originally Posted by AGarvin

Brian,

Try here.

Andrew.

Thanks for both replies, first I will use SOS and then move on to the more advanced web site.
Brian

[skwinty (Steve)]

You seem to be implying that Einstein was a failure.
Considering his incomplete theories are still subject to rigorous testing today and so far have not been proven to be false. Sure he was a human and subject to human frailties.
Einstein's self admitted biggest blunder (The piece of fudge called the cosmological constant)may yet prove to be his biggest truimph.
If you look at string theory, the mathematics are also having to be made simpler by making a lot of assumptions and mathematical compromises.
As far as saying that I am not thinking and accepting Einsteins theories at face value without applying any thought, then the same could be said for people like:
1. Owen Gingrich.
2. Steven Hawking
3. Brian Green
4. Jeremy Bernstein
5. Gerald Holton
6. Shimon Malin
7. John Stachel
8. John Archibald Wheeler
9. Richard Feynmann
10.Julian Schwinger
12.Roger Penrose
The list grows much longer and these are well known authorities in Astronomy, Mathematics and Physics of every persuasion.
You make a point saying that any theory that introduces infinities into its equations is meaningless and incorrect in its assumptions.
Well, mathematics introduces infinities as one of its basic axioms (n+1) so does that mean that mathematics is incorrect.
Space as far as we know is infinite so any theory that discards infinity surely then must be incomplete.
The mathematical universe has infinite complexity and is not fully comprehensible to us humans and this is why Godel came up with his theory of incompleteness.
Given that Einstein died in 1955 and never had the benefit of modern technology, which in a lot of cases wouldn't have been available today if it wasn't for his incomplete theories.
Sure he had a problem with randomness, quantum theory and its paradoxes but did that make him unsuccessful?
To quote Richard Feynmann "I can safely say that no one understands quantum mechanics"
Randomness is upsetting to mathematicians but only an outsider to mathematics would venture this statement.
Just because infinities makes things more difficult to understand and compute doesn't make it incorrect and meaningless.
You stated in your post that there is something is "obviously" very wrong with SRT.The hint you gave was to look at the answers derived from the equations.
My question is then why did it take so long before some one could see this obvious mistake.

[AGarvin]

Here's something for all of you to think about... there's something seriously wrong with Special Relativity and it should be rather obvious.

I think this is another common problem, expecting more from a theory than it's capable of. All theories have a framework that they work within and it's is just as wrong to call a theory seriously flawed by expecting more than it is "designed" to do as it is to assume it's the be all and end all.

By this "its seriously wrong" logic even newtonian mechanics is seriously wrong because it's wrong at "relativistic" levels but it works perfectly in everyday life.

[renormalised (Carl)]

You seem to be implying that Einstein was a failure.

Einstein wasn't a failure, and I never stated that explicitly. What I said was that SR had problems and that he had a hard time trying to understand Quantum Theory.

Einstein's self admitted biggest blunder (The piece of fudge called the cosmological constant)may yet prove to be his biggest truimph.

Yes, and you're correct in that assumption, providing that what we observe as an apparent acceleration of universal expansion is actually occurring. Rather ironic, don't you think??. Einstein would probably laugh about it, if he was still alive.

If you look at string theory, the mathematics are also having to be made simpler by making a lot of assumptions and mathematical compromises.

You make a point saying that any theory that introduces infinities into its equations is meaningless and incorrect in its assumptions. Well, mathematics introduces infinities as one of its basic axioms (n+1) so does that mean that mathematics is incorrect.

Yes, there are a lot of assumptions and compromises in String Theory and in other related theories. Much of it due to the appearance of infinities in the equations of the theories. That's why I explained about renormalisation....it's to remove the infinities from the equations, otherwise the equations don't work. They produce nonsense or undefined answers. If the infinities were OK, then the mathematicians and physicist wouldn't bother trying to get rid of them!!!. N+1 is only infinite if you take the value of N to infinity. N can be defined in any way you choose, depending on the system you're working with...and when it approaches infinity, the answer to N+1 becomes undefined, It's an impossibly large number.

As far as saying that I am not thinking and accepting Einsteins theories at face value without applying any thought, then the same could be said for people like:
1. Owen Gingrich.
2. Steven Hawking
3. Brian Green
4. Jeremy Bernstein
5. Gerald Holton
6. Shimon Malin
7. John Stachel
8. John Archibald Wheeler
9. Richard Feynmann
10.Julian Schwinger
12.Roger Penrose
The list grows much longer and these are well known authorities in Astronomy, Mathematics and Physics of every persuasion.

So...they can only go by what they have learned and know. However, it doesn't mean that they can't questions Einstein's basic assumptions and the veracity of any formulations he made...and most of those guys have. Why do you think most of these guys have come up with various Quantum Theories.....why the great push for a theory of quantum gravity. It's because Einsteins theories only work so far... it's the same with Newtonian physics. Good for some situations and not for others. Now, even these new theories have run into trouble along various lines. Not just for infinities cropping up in equations, but it's one reason why.

Space as far as we know is infinite so any theory that discards infinity surely then must be incomplete. The mathematical universe has infinite complexity and is not fully comprehensible to us humans and this is why Godel came up with his theory of incompleteness.

These assumptions are entirely due to our lack of knowledge and understanding. We believe things to be infinite because we can't see any other way that they can be... all due to a lack of the complete facts. Essentially why Godel came up with his theory. It's the old axiom:

"The more we think we know, the more we realise the less we actually know and understand"

To quote Richard Feynmann "I can safely say that no one understands quantum mechanics"

I totally agree with him!!!!

Randomness is upsetting to mathematicians but only an outsider to mathematics would venture this statement. Just because infinities makes things more difficult to understand and compute doesn't make it incorrect and meaningless.

The first sentence you wrote here, about randomness, is rather odd. If something is upsetting to someone, then why wouldn't that someone venture the fact that it upsets them??!!. If someone from outside maths said that randomness upsets mathematicians, then he/she is only stating a fact that the mathematicians already concur with!!! Why would mathematicians want to try and renormalise equations that produce infinities if those infinities didn't create problems for them. Since they do try to renormalise their equations, then it's safe to say that having infinities crop up in your theories does cause problems and is a cause for concern amongst mathematicians (and physicists).

Suffice to say, your assumption that it took so long before someone could see the obvious mistake in SR is incorrect itself. They've known for decades about the problems with relativity. However, it doesn't mean that the entire theory should be thrown out with the bathwater, so to speak. Like Newtonian physics, it works...upto a point. But then the problems with the theory crop up and it no longer works (or works rather difficultly) in those situations where the theory is stretched beyond its limitations. Having infinities crop up in your theory is a sign that you're reaching those limits. All mathematicians and physicists recognise this, otherwise they wouldn't try to use methods such as renormalisation to get rid of them.

If you want to read a reasonably well written piece on renormalisation, go here:

http://en.wikipedia.org/wiki/Renormalization

[avandonk]

We can calculate the quantum energy levels for an isolated Hydrogen atom (one proton and one electron) and that is it. Forget a Hydrogen molecule! It is called the three particle problem.

I gave up on fundamental Physics to concentrate on biological molecules as it seemed to be a far more unmined resource for self serving scientific grandeur. It may even give us some insights as nature has been running the experiments for about four billion years.

All jokes aside we nearly have the tools to make the tools to even start to solve the fundamental problems.

Looking at the problem from a perspective we cannot now imagine may solve it. Chucking in a fudge factor is a cop out. We may as well invoke the easter bunny or the tooth fairy!

Bert

[sjastro]

Originally Posted by renormalised

Anyway, here's the problem. Any theory which introduces infinities into its equations, either as part of the workings or as a solution, is meaningless and incorrect in its assumptions.

This is not true with SR. If one plots the Lorentz factor 1/sqrt(1-(v2/c2)) against velocity v, an asymptote is found at the line v=c. In this case an infinite Lorentz factor tells us that particle velocity cannot reach or exceed the speed of light c.

Regards

Steven
http://users.westconnect.com.au/~sjastro/small

[sjastro]

Originally Posted by avandonk

Looking at the problem from a perspective we cannot now imagine may solve it. Chucking in a fudge factor is a cop out. We may as well invoke the easter bunny or the tooth fairy!

Bert

Strange how fudge factors are looked at in such a negative light particularly when it brings theory and fact closer together. The cosmological constant is a very successful fudge factor, as was the ad hoc introduction of 1/2 spin numbers in quantum mechanics which were theoretically verified by the application of SR to quantum mechanics.

Regards

Steven