Is gravity an infinite source of energy?

[Xtensity]

Photon has energy. E = mc^2. Therefore photon has mass.

See this is where I get confused to a degree. That formula is based on a constant which is derived from a measured speed of a photon.

If c is just the speed of the photon, and the photon has a mass.. If there exist a particle lighter than a photon, then why would we still use C as what it currently is? Or am I misunderstanding something?

Edit: Would this insinuate that we do have a very accurate measure for energy, but the discovery of a lighter particle would also lead to discoveries of a higher speed, which would inturn lead to more accurate predictions of energy content(to higher decimal places)... Since the formula is the energy more or less as mass approaches the limit of 0?

 

[russ_watters]

There's key words here though. Very high accuracy, "seems like". Of course with such its fragile size that we can not measure it perfectly, as the probability of that is very low. Though I am confused in the area of, if we are so sure that it is massless, then why is there that area of uncertainty?

That's just how science works: no measurement can ever be 100% accurate and no theory can ever be 100% proven. So the best we can do is 99.9999999999999% certain.

 

[Xtensity]

That's just how science works: no measurement can ever be 100% accurate and no theory can ever be 100% proven. So the best we can do is 99.9999999999999% certain.

I realize exactly that, which is why we can only measure to a certain level of mass accuracy.

Does that not defy the Mass–energy equivalence formula to say that the photon is massless, when the formula says otherwise? We know the photon has energy.

Isn't it unscientific to say the speed of light is the top speed? Wouldn't it be more accurate to say it's the highest speed we can measure, but there very easily could be higher speeds if lighter particles existed that we don't have the current technology to measure? I'm sure everyone can agree it will always be unscientific to say we've reached the peak of universal discoveries.

 

[n.karthick]

I'm just confused as to why we assume its massless(besides aforementioned speed of light reason)

Reading a physics book and understanding the theory first before jumping into doubts/conclusions can solve all your confusions.

What is discussed till now is 100 years old theory and if you comprehend it, you will be in a better position to ask right questions. All the best.

 

[russ_watters]

Does that not defy the Mass–energy equivalence formula to say that the photon is massless, when the formula says otherwise? We know the photon has energy.

That formula is not saying the photon has mass. That's a common misuse of the formula.

Isn't it unscientific to say the speed of light is the top speed?

Of course not! A theory predicts it, all evidence we have to date validates the theory, and no other theory exists that can explain the evidence. That's perfectly scientific.

Wouldn't it be more accurate to say it's the highest speed we can measure, but there very easily could be higher speeds if lighter particles existed that we don't have the current technology to measure?

Certainly not. There is no theory that predicts a non-zero mass for the photon that doesn't contradict the evidence we already have.

I'm sure everyone can agree it will always be unscientific to say we've reached the peak of universal discoveries.

Of course. That's not what's being claimed. What you're claiming is no less profound: That a 100 year-old, exquisitely well proven theory is wrong. That would be Earth'shattering.

 

[Xtensity]

Russ I understand what you're saying, but why is there that area of uncertainty.

Yes there are countless test reverifying that the mass of a photon is very small. Just because no theory exist predicting otherwise does not mean that 'otherwise' isn't true. If a smaller mass, under the already known range, were predicted, that wouldn't contradict the current test done on the speed of light.

I'm baffled at the level of certainty that exist for something so small. I mean, I can completely understand the it being measured under <1×10−18 eV, because we can confirm this.

But we can not confirm masslessness, we can only predict really close to it, which is why it baffles me that we can just say, there is no mass. We can't verify no mass, it's logically impossible, we can only verify extremely small masses.

Edit: you also say

Of course. That's not what's being claimed. What you're claiming is no less profound: That a 100 year-old, exquisitely well proven theory is wrong. That would be Earth'shattering.

I'm not saying the proven theory is wrong. In fact, I wouldn't use the word proven. All the test that have been done only reassure us that it lies under a certain range. It does not prove massless, it only proves that it is under a certain range.

Or unless you know of a way to measure, the lack of mass. Which would have to go on the assumption that we can measure things infinitely small, which we can't, there's limits to our technology, this fact can not be argued, the method can though. So if you have some method I am unaware of for measuring masslessness or infinitely small numbers, please do post it.

 

[russ_watters]

Russ I understand what you're saying, but why is there that area of uncertainty.

We're starting to go in circles here: It is a combination of logic and measurement imperfection. The uncertainty in the measurement exists because it is impossible to have 100% measurement accuracy. At the very least, measurement devices are man-made and therefore have flaws that can never be completely eliminated.

And logically, the uncertainty in the measurement plus the fact that you can't ever measure the speed of every photon means that you can't ever prove that every photon moves at C.

Do not make the mistake of believing that this little opening is a place where scientists should be looking to build a theory of a massive photon. It's simply a demonstration of the level of scientific certainty and its limits.

Yes there are countless test reverifying that the mass of a photon is very small. Just because no theory exist predicting otherwise does not mean that 'otherwise' isn't true.

Of course: Being 99.999999999% sure of one thing means there is a 0.0000000000001% chance that there is something being missed.

But we can not confirm masslessness, we can only predict really close to it, which is why it baffles me that we can just say, there is no mass. We can't verify no mass, it's logically impossible, we can only verify extremely small masses.

That's not quite right. First, the prediction is masslessness. I think you meant measurement: A measurement would say something like 0.01 +-.02, which verifies that the mass is somewhere between -.01 and +.03. .03 is an upper bound in the range. So the experiment verifies no mass (because 0 is inside that range) to within a certain accuracy.

 

[Xtensity]

We both agree there is that level of uncertainty. Can we agree that the possibility for a very small mass of a photon does exist, we just can't measure it? The theory of a "massive photon" would not contradict any theories, other than the notion of it being massless(which can't be 100% accurate obviously).

I'm not trying to establish any scientific theories here, just trying to establish that the possibility 'does' exist. It's talked about as if it's nonexistent, when it very well may be measurable in the future.

(also if you want to take the time, could you clarify why "That's a common misuse of the formula.", so I can understand for future references)

 

[DLuckyE]

Isn't mass just energy in a different form? And a photon is just energy? Which would make it impossible for a photon to have mass(per definition that is)?

 

[Xtensity]

Isn't mass just energy in a different form? And a photon is just energy? Which would make it impossible for a photon to have mass(per definition that is)?

That would clarify a lot if true, but if that's true, then what is the entire point of attempting the measure the mass of a photon?

 

[xAxis]

I think this shouldn't really be discussed here, but well. No theory can be 100% proven. The entire point of measuring the mass of a photon is in my opinnion that it would disprove the theory "directly".
And I think this is the mistake:

"The theory of a "massive photon" would not contradict any theories, other than the notion of it being massless"

The theory is not just one notion. Measuring the mass of a photon would disprove the entire theory of relativity, and probably some other things and concepts too.

 

[Xtensity]

I think this shouldn't really be discussed here, but well. No theory can be 100% proven. The entire point of measuring the mass of a photon is in my opinnion that it would disprove the theory "directly".
And I think this is the mistake:

"The theory of a "massive photon" would not contradict any theories, other than the notion of it being massless"

The theory is not just one notion. Measuring the mass of a photon would disprove the entire theory of relativity, and probably some other things and concepts too.

It wouldn't disprove the theory of relativity because we have already tested it and can verify a large portion of it. It may alter the theory, but that's it.

If a photon mass was discovered then it could lead to the discovery of other particles, which would make it so there would be better numbers to use than c in the mass equivalence formula... but the overall measure of the amount of energy would only change slightly. It would expand the formula or open up another formula for use.

The discovery of a potential massive photon would not destroy all of the current theory of relativity, I don't understand how you can say that when a majority of it has already been proven. All it would do is redefine it and make it more accurate.

Edit: If you haven't realized, Massless is not an undefinable number, massless means 0. Think of it this way, if a mass was discovered for a photon(smaller than we can currently measure obviously), then it would just move the scale up slightly. I don't see how you can say it would destroy the entire theory.

 

[xAxis]

I am not an expert on R.T., but am pretty sure it would destroy it, someone might back me on it. But again, it really shouldn't be discussed under this topic.
Also you should understand that no theory can be 100% proven, that's how physics works.

 

[Xtensity]

I am not an expert on R.T., but am pretty sure it would destroy it, someone might back me on it. But again, it really shouldn't be discussed under this topic.
Also you should understand that no theory can be 100% proven, that's how physics works.

I understand no theory can be 100%.

If it would destroy it, I am curious as to why, because from my PoV that doesn't seem like it would happen, but I'm probably wrong..

 

[Jack21222]

Of course it's possible that photons have mass. It's also possible that I'll quantum-tunnel my way into your room after I make this post to tell you that in person.

I am not aware of any coherent theories that predict a massive photon. When you come up with one, let us know. Otherwise it makes no more sense to talk about a massive photon than it does to talk about a 5-headed unicorn that lives underneath the Gobi desert.

 

[Xtensity]

Of course it's possible that photons have mass. It's also possible that I'll quantum-tunnel my way into your room after I make this post to tell you that in person.

I am not aware of any coherent theories that predict a massive photon. When you come up with one, let us know. Otherwise it makes no more sense to talk about a massive photon than it does to talk about a 5-headed unicorn that lives underneath the Gobi desert.

That wasn't what I was insinuating. If any mass was discovered, it would be so small that it wouldn't make a difference in any practical application.

When I was talking about the possibility, I was saying that numbers can get infinitely small. Meaning there could be several trillion+ smaller numbers that we simply can't measure to because we don't have the technology, a number which would infact represent the mass of a photon. Even if it did have a mass why would that matter... What's 0 compared to 0.0000000000000000000000000000000000000001? Any mass that the photon could have would be so small that it wouldn't make much of a difference in calculations. Of course a massless photon would allow the theory to work fine because most often no one deals with calculations that near the speed of light or in that potential decimal range of accuracy(if the photon had mass). Sure measurements are done all the time, but we can only be so accurate. Meaning if the speed of light was derived from a particle believed to be massless, and that particle ended up not being massless it wouldn't make much of a difference. We already know what we can do with the formula and the photon having 10x^-200 more mass than we thought it does isn't going to change anything, besides what we believe to be the fastest speed possible. The formula would just become more accurate.

I still don't understand how it would totally destroy the theory of relativity if we have tested it countless times so we KNOW for a FACT that we are in the right range and the calculations are accurate. Explain to me how a photon with even 10x^-200 mass more than 0 would destroy this theory.

Even if the photon had 10x^-200 more mass than we thought(0) then it still wouldn't make a difference because how often do scientist deal with numbers in the 200 decimal range?

 

[Jack21222]

Explain to me what point you're trying to make. You seem to just want to be contrarian for no reason at all.

 

[Xtensity]

? I'm not opposing anything really. I agree the photon has an immeasurable mass(with todays technology), but I simply feel that saying it is massless is quiet a jump considering how infinitely small decimal numbers in terms of mass could get.

I'm also curious how it would destroy the entire theory. That doesn't make any since when we can verify that the theory is extremely accurate for modern uses.

Just the part that's disturbing me the most is the notion that its massless when the chances are MUCH higher that it could just have a mass of an number very small(in the 50-200+ decimal range for say electron volts) or very hard to measure. I understand its accepted as massless for modern purposes, but to actually believe it has no mass it quite an assumption given the odds and the fundamental nature of numbers.

 

[russ_watters]

I'll address specific points when I have more time after work, but...

This posture you are taking of scouring the error margins of current experimental proof for a place to keep your emotion-based objection to a exquisitely well proven scientific theory is *highly* unscientific and will prevent you from ever learning how the universe works if you don't fix it.

 

[Xtensity]

I'll address specific points when I have more time after work, but...

This posture you are taking of scouring the error margins of current experimental proof for a place to keep your emotion-based objection to a exquisitely well proven scientific theory is *highly* unscientific and will prevent you from ever learning how the universe works if you don't fix it.

I have no emotionally based objection. The entire reason I am forming this viewpoint is because of logic. It is logic which allows us to understand that numbers can be infinitely small. I am probably the most open minded person you will meet, but I still try to be logical with my opinions.

Last time I checked, it is highly unscientific to say any number is certain. It's like, if you have a graph, and you take the area under the curve to find the percentage likely hood of landing in that area, if you take 1 number, the chances are extremely slim. Which is why it is much more likely that it is in a range, and not at a specific number; this is basic statistics. It is also very likely that we simply can not measure numbers that small and the most accurate we can currently get is 0, saying we have perfect measurements is unscientific. It's like when they believed the atom was the smallest particle.

I am extremely open minded but I try to use logic when I form my opinions. I'll appreciate any effort you make to helping me understand this, but as far as I can currently see, the most rational choice in terms of probability is that the Photons mass is smaller than we can measure. It could be massless, but that's quite an unscientific assumption in terms of numeric probability and I fail to see how it would totally destroy the theory of relativity.I can assure you my opinion is not emotionally based, I am just not so suaded when I see more probable evidence. Regardless of what my opinion is on the subject, it won't effect my life in any way. If it's on a test, then I'll study what will be on that test.

The only reason I'm seeming so stubborn is because I don't comprehend how you can argue that its unscientific despite the odds. Everyone past 6th grade math should understand numbers can be infinitely large and infinitely small.

 

[Janus]

I still don't understand how it would totally destroy the theory of relativity if we have tested it countless times so we KNOW for a FACT that we are in the right range and the calculations are accurate. Explain to me how a photon with even 10x^-200 mass more than 0 would destroy this theory.

Even if the photon had 10x^-200 more mass than we thought(0) then it still wouldn't make a difference because how often do scientist deal with numbers in the 200 decimal range?

In Relativity there is a huge difference between 10^-200 and 0 when it comes to mass. Only particles that have exactly zero mass are required to travel at c and only at c. The smallest amount of mass whatsoever means that the particle is allowed at any speed from 0 to almost c. If photons had any mass at all they could travel at any speed. However, we only measure photons as moving at c. We never measure any photons (in a vacuum) traveling at 0.99c or 0.1c or 5 km/hr.

 

[stewartcs]

Photon has energy. E = mc^2. Therefore photon has mass.

No, a photon does not have mass. You are using the wrong formula. Try using the complete and correct forumula:

$$E^2 = m^2c^4 + p^2c^2$$

CS

 

[Xtensity]

In Relativity there is a huge difference between 10^-200 and 0 when it comes to mass. Only particles that have exactly zero mass are required to travel at c and only at c. The smallest amount of mass whatsoever means that the particle is allowed at any speed from 0 to almost c. If photons had any mass at all they could travel at any speed. However, we only measure photons as moving at c. We never measure any photons (in a vacuum) traveling at 0.99c or 0.1c or 5 km/hr.

Thank you.
Very informative, something very obvious that wasn't so apparent to me.

That 1 post just practically solved the entire thread and my confusion, and it's basically what I was asking for the whole time. Thank You again. I don't see why it takes 4 pages of asking why and why not to get that kind of simple explanation.

 

[Chronos]

Many roads lead to the same destination.

 

[Shins]

I had to register and comment on something somebody said on page 1.

They said that tidal energy harnesses the rotational energy of the earth. If the Earth were not rotating at all, the tides would still be affected by the rotation of the moon.

The Earth would have to be rotating in sync with the moon for there to be no tides. If the Earth were rotating faster opposite to the moon, the tides would be faster.

So where does the energy come from? the moon's kinetic energy? or the difference in rotation between the Earth and moon?

If you were to harness both the "ebb" and "flow" would the supposed rotational impact cancel out? When the moon is directly above you, does it create "anti-gravity" in relation to objects on the earth? do objects become lighter in relation to the earth?

When the moon is on the direct opposite side of the earth, does gravity increase for objects on the opposite side of the earth? do objects become more heavy?

 

[sophiecentaur]

Some simple, Classical points - no warped space or speed of light arguments - just to get the ancient basic bits straight.
There is always gravitational potential energy between the Earth and Moon in the same way as there is GPE of the water in a reservoir. The reservoir is not moving so you can only use that GPE once - whilst the water falls down through a turbine. However, the Moon's orbit is much slower than the rotation of the Earth and it 'lags behind' the Earth's rotation. This means it is constantly pulling against water, causing a wave to move around the Earth (East to West) once a (iunar) day and for a net flow of ocean water 'backwards'. This force is also pulling the Moon 'forward' so its orbit is constantly increasing by a bit. The flow of water around the oceans (and through your tidal generators) involves Energy loss / transfer to heat etc. but the total Momentum remains constant (basic conservation law). Whether the tide is ebbing or flowing, energy is still transferred.
If this process were allowed to continue to completion, the Moon's orbit would be very large and the Earth's rotation speed would slow down and be the same as the Moon's (new and slower) orbital speed. Then there would be no tidal drag - just two stationary tidal bulges- one towards and one away from the Moon.
Yes, the Sun also has an effect but let's deal with one thing at a time.
Wherever the Moon is in its orbit, its gravitational attraction adds 'vectorially' to the Earth's attraction. Sometimes it adds, sometimes it subtracts and sometimes it adds in another direction. The effect is minute and I don't think it can be measured directly with a balance. But the cumulative effect (coupling) to the movement of the oceans over many cycles produces a very noticeable tidal effect. On a smooth sphere, with no land - so much less friction, the tides would be huge.

"If the Earth were not rotating. . . . " In that case, the tides would occur twice a month and would be enormous, because the water would have plenty of time to flow towards and away from the Moon's position. This would be the scenario described earlier - once the two bodies have achieved synchronism. I wouldn't want to be around then!

 

[Macocio]

If we use the energy (let's say from the ocean caused by the gravitation of our moon), then we would disturb the Earth's natural centre point of gravity and therefore we can not say that gravity is an infinite source of Energy. Newton's law of universal gravitation states this clearly. F = G(m₁m₂/r²)

r is the radius between two masses their centre point of gravity.

 

[sophiecentaur]

There is no "infinite source of energy", whether we're talking about the Moon or Joe Soap's 'perpetual motion machine'. It is a meaningless concept.
Why do people keep looking for loopholes in this argument?

And, despite what they say in the press, the energy we can / could extract, in practice, from astronomical systems is not relevant to the state of the Solar System.

 

[Borek]

And, despite what they say in the press, the energy we can / could extract, in practice, from astronomical systems is not relevant to the state of the Solar System.

Yet

 

[sophiecentaur]

Ever?

 

[sophiecentaur]

Ever? (Dr Strangelove)

 

[Borek]

Wait till we build Dyson sphere.

 

[sophiecentaur]

Materials to be obtained from Travis Perkins no doubt.

 

[Radrook]

What he is asking is whether the object that is the source of the gravity will ever run out of gravitons via using them all up just as a star uses up all its available fuel and eventually stops shining. Hope that clears up the confusion.

 

[sophiecentaur]

Gravitons aren't like that. They are only exchanged when there is some Energy transfer, I think. If there is no change of gravitational Potential then no gravitons are involved.