# Thread: E = mc^2

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## E = mc^2

It seems to me Energy (V) can create gravitational acceleration by plugging in:
E = mc^2
m = ar^2/G

What am I missing here?

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2. Originally Posted by philippeb8
What am I missing here?
Nothing. Mass is energy, energy is mass, mass-energy produces a gravitational field.
If you shine a torch into a black hole, it gains mass by absorbing photons.

Grant Hutchison

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Thanks!

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4. My only question is about your graph there. So yes, energy of any form has an equivalent mass, which will indeed produce a gravitational field. But it takes a lot of energy to do so in any measurable way. Your graph appears to have a pretty large acceleration at a short range. I'm not quite sure what amount of energy you're thinking about here, since your graph says 2.5e7 V, but V usually means voltage, not energy. Can you clarify what you had intended?

I went ahead and ran the numbers. If I haven't made any mistakes here, to give approximately 1g acceleration at 0.1 meters, as your graph suggests, that means you'd need the equivalent of about 1.5 billion kg mass, which has to be contained within that 0.1 meter radius sphere That's a density of about 3.6 x 1011 kg/m3 (a few orders of magnitude higher than a white dwarf, but still a few orders of magnitude less than a neutron star, so doable in principle, but not easy). The energy equivalent to that mass is about 1026 joules, which is about equal to the energy emitted by the Sun in a third of a second. So you'd have to collect all of those photons, and confine them to that 0.1 meter radius sphere to give you the gravitational effect your graph shows just from energy. Even if the energy is in some form other than light, you'd still have to somehow collect and confine it.

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I just convert Joules and Voltage with Coulombs:
E = C * V

Ok so this and gravitomagnetism are all correlative. Thus there's definitely a way to harness all that.

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6. Again, gravitomagnetism has nothing to do with electromagnetism. It's a purely gravitational effect produced by mass flux.

Grant Hutchison

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I know but they're all related.

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8. Originally Posted by philippeb8
I just convert Joules and Voltage with Coulombs:
E = C * V
Okay. So you're imagining the energy of pushing charge with that voltage. Just to be clear, though, to get that 1026 J, that would be the energy of pushing 4 x 1018 C* at a voltage of 2.5 x 107. You have to have the energy present, not just the raw voltage. You won't see any measurable gravitational effects just by achieving a potential difference of 25 million volts between two terminals. (As a note, it appears that 25 million volts is about the upper limit for a Van de Graaff generator, if you run it in a chamber filled with insulating gas instead of air. But a Van de Graaff generator won't have anywhere near that kind of charge or stored energy.)

* To get an idea of just how much charge that is, that works out to stripping all the electrons from 80 billion kg of matter.

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Ok thanks.

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10. Originally Posted by philippeb8
I know but they're all related.
But not usefully so.
If you have the energy available to push x number of coulombs at y volts, you already have the mass-energy to generate a given gravitational field. Moving charge around isn't going to change that fact.

ETA: In other words, a charged battery weighs more than an uncharged battery.

Grant Hutchison
Last edited by grant hutchison; 2021-Oct-26 at 08:44 PM.

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## E = mc^2

Well we need to start somewhere. Furthermore, wasn't linking all forces Nobel Prize material?

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12. Not in Q&A…and you should know that by now.

13. Originally Posted by philippeb8
Well we need to start somewhere. Furthermore, wasn't linking all forces Nobel Prize material?
Yeah.
I think the issue here is that, while kaleidoscoping some basic physics equations can provide educational insights into how basic physics works (in this case, the importance of the concept of energy), it's about a century behind being Nobel Prize material. I don't denigrate the endeavour (quite the reverse) but one has to moderate one's expectations.

Grant Hutchison

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I don't have any more questions other than possible QM ones but the astrophysics layer is very clear to me.

Thanks to everybody I really appreciate.

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