Is gravity an infinite source of energy?

AI Thread Summary
The discussion centers on whether gravity can be considered an infinite source of energy, particularly in relation to hydroelectric power generated from tidal waves influenced by the moon's gravitational pull. Participants argue that while gravity affects tidal movements, it is not a source of energy itself but rather a static force that does not "run out." The energy harnessed from tidal waves is derived from the Earth's rotational kinetic energy rather than gravity directly. Additionally, the conversation touches on the idea that energy from waves can be captured, but this process does not significantly impact the Earth's rotation over short periods. Ultimately, gravity's role is more about facilitating energy transfer rather than being an energy source on its own.
  • #51
Jack21222 said:
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?
 
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  • #52
Explain to me what point you're trying to make. You seem to just want to be contrarian for no reason at all.
 
  • #53
? 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.
 
  • #54
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.
 
  • #55
russ_watters said:
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.
 
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  • #56
Xtensity said:
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.
 
  • #57
Blenton said:
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
 
  • #58
Janus said:
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.
 
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  • #59
Many roads lead to the same destination.
 
  • #60
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?
 
  • #61
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!
 
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  • #62
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.
 
  • #63
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.
 
  • #64
sophiecentaur said:
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 :devil:
 
  • #65
Ever?
 
  • #66
Ever? (Dr Strangelove)
 
  • #67
Wait till we build Dyson sphere.
 
  • #68
Materials to be obtained from Travis Perkins no doubt.
 
  • #69
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.
 
  • #70
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.
 
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