How is a light photon affected by Gravity? 

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I haven't been able to understand the gravitational redshift mathematically before...but thanks to you ,now i know it in a very simplest manner🙏

I humbly request you to please discuss about the general theory of relativity

Wow…. Speechless ! Amazing to see how you have been explaining complex topics in such lucid manner 🙏

Very clear math and excellent commentary along the way. Thank you!!

Thank you bro! Appreciate it 🤟 i was looking for this topic explanation literally everywhere

You perceive physics the way it is projected in your mind. Tx for ur fantastic explaination

Straight to the point, excellent video!

Beautiful presentation. Thanks.

Very clear presentation, Thank You.

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Excellent! Thank you!

Lucid, accessible presentation! Thanks

Thanks for such great efforts.

Thank you for this educational lecture!

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this video was sO helpful, im doing a project and this video is frickin beautiful, ty

Superb made much easy to understand a complex topic

Beautifully explained, 👍

It's crazy I came here because I wanted to listen to John Mayer's Gravity and gave this video a go. Not at all regretted clicking this.

very lucid explanation. excellent

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This is a man, who know what he does Lots of love 💗

Very clear video, thanks. Cheers from France.

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What a nice explanation.. 👏

It helped me a lot. Thank you.

Very nice explanation !!

You explain very well sir. Thank you

Sir your lectures are extremely good. such a nice explanation of the things. Sir keep uploading the videos🤩

Perfect crystal clear explanation in a simple and sophisticated way.

Nice one , easy to learn

Thanks verry good example

Excellent 👍

Thank-you so much

mind blowing👌🏻♥️

Wonderful.. Summarised this at the end stating the difference between Doppler red shift with gravitational red shift. 👍☘️☘️👍

Thank-you so much...

Sir...your lecture are phenomenal and in addition to that, your handwriting is incredibly neat 🌸

Nice explanation. Very important calculation every astrophysicist has to do. Light we detect from faraway galaxies helps in predicting things like Blackholes etc.

Thank you so much sir!!

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I love your voice and your teaching........

Best explanation

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That was AMAZING! Your second interpretation of red shift was wonderful. Can we interpret the final dispersion of red shift by removing Plank's constant and substitute Plank's with another formula? Perhaps Mass to energy, -E+Kv=0/P -G+em? What distance does the last photon particle travel and what is the final principle of dispersion? Are angular and rotational kinematics of photaic mass considered in the gravitational model? Can we measure the final dispersion pattern from an absorption plate and reverse calculate the primary Mass of the 0 point? Thank you! 🙏💖🌱🌍🌱

Thanks sir

Thanks for you

Thanks very much for another great video. What happens to the energy that the photon loses? Where does it go? The star is not a BH. Who gains the energy the photon loses?

Im relatively new to this concept but its crystal clear to me! Great video!...but it raises a new question - what happens to photons as they ENTER a planets gravitational feild and if the photon has no mass is the gravitational redshift just an example of time's effect on the photon?

You used the term “effective mass” for a photon based on its frequency. I think that is an excellent way to represent a massless entity. Is there a theoretical minima and maxima frequency for a photon ? Thanks. Your videos are clear and therefore riveting. Anand

Thnk u

Can you actually solve for average redshift ? I'm curious to see how many nm shift occurs as a photon leaves earth and/or the sun

Thank you for the very practical explanation. This has been a question I've had for a while and you answered it in a way that I can grasp.

Thx

Excellent demonstration. It has been said that e=mc2 formula does not apply to the photon due to the presence of mass m but to everything else.

I read that gH/c^2 is an approximation for the relative change of the frequency of the photon in Earth's surface, where H is the difference in altitude and g is Earth's surface acceleration. Do you know how can I prove that this is a good approximation? I ask that because I get very different results if I proceed as you explain in this video.

Thank you for your interesting & clear lecture! I just wondered, so all incoming light observed at the surface of the earth is slightly blue shifted?

Sir,if there is a shift in frequency then what happens to the energy lost by a photon during its escape...is energy conservation law doesn't hold up here....?

Light bend around sources with high mass due to gravity. This is not because the mass pulls on the photons directly, but instead because the mass warps the space.

big fan of your work sir.............. but I think i have one more explanation that photons have the influence of gravity on it .... for this first consider the equation relativistic energy from special relativity i.e E^2=(M'C^2)^2 + p^2c^2 ... where m' is the rest mass of the particle (0 in the case of a photon). Hence this reduces to E=pc. Einstein also introduced the concept of relativistic mass (and the related mass-energy equivalence) in the same paper; we can write it as: mc^2=pc m=relativistic mass, hence: m=p/c in simpler word a photon does have relativistic mass proportional to is momemtum. (II) = De Broglie's relation, an early result of quantum theory (specifically wave-particle duality), states that : λ=h/p ; h = planks constant = 6.62607*10^-34 m^2 kg/s we can write is as: p=h/λ hence combining this with equation of relativistic energy; we get: E/c^2=m=p/c=h/λc; m= relativistic mass. so form this we can conclude that , photons have 'mass' inversely proportional to their wavelength! Then simply by Newton's theory of gravity, they have gravitational influence. I hope that you would consider it sir thank you......

Sir if frequency changes constantly as we go up due energy conservation, then mass of photon should also change, then how can we calculate it directly by energy conservation

hard..👌💝

We need more in general theory of relativity by simple example

Bravo, the first part of the formula was tested in MIT by the gamma ray photons experiencing red shift through a vertical duct. The second part refers to the black holes' thermal radiation.

How do you know if you're observing gravitational redshift or redshift caused by motion?

Bro E=mc^2 is applicable for stationary objects , how you can applied for photons . For photons E = √(m^2C^4+p^2c^2) . Please reply

good.. change in frequency has effect on energy (hf`=E`) SO further change will effect mass and speed of light (E`=m`c^2) so mass has to change itself to keep speed of light constant..then tell me is mass infinitly large enough to cause the light not to escape from the blackhole..what will be the speed of light against blackholes surface .is it constant or zero? rediculs

Hello sir... But the ball is initially at rest. So v equals to zero and so does kinetic energy. So how kinetic energy of ball at below is half of mc squared?

Can u advice me best book for GR... Like zettli and Griffith for QM.... And Leonard suskind is better for special theory or some one best than this

zbardast...

there are two problems. first is can you apply mass energy equivalence on photon? and second is the quanta energy which we are taking hv here can be compared with classical potential energy? This could rather be explained using lorentz transformation on energy.

Can the last derived equation be used for black holes?

Sir discuss general theory of relativity

Great explainer. Now I understand how a light photon is affected by gravity. But what about a heavy photon?

I find an another teacher❤

Okay, so if we apply this to a light photon, trying to escape black hole's gravity, what would be the case? ? As u said,speed won't change but freq would decrease. So if freq decreases, wavelength must increase. Concluding that momentum of individual photon would decrease? ( P=H/lambda) where p=mc So basically mass of each photon decreases so maybe the mass of photon tends to zero and wavelength tends to infinity. So maybe light escapes but it's mass is so small and it loses the characteristics of light

sir if frequency decreases ,but red has higher frequency and hence high energy.Then why red shift

Sir please kindly let me know as mass of photon is given by m=hv/c^2 ...h & c are constants, since we have range of frequencies that is we have electrospectrum different wavelengths and frequencies does it mean different photons associated with different frequencies have different MASS PLEASE ANSWER.

Can you explain more about why it is you think light can completely escape the gravity of a star? You seem to suggest that there is asymptotically flat space, which I’m not convinced there is. Arguendo, assuming light could escape the gravity of the emitting star, would that light not then be affected by the gravitational mass of everything it encounters between us and the star, thus, shifting it even further red?

answer mi ..why there is no neutrons in hydrogen atom , and present in its isotope ????

Wow

Hlo Dear Sir How are you I hope you will be fine dear Your every topic is well explained Please Sir make videos on LASER subject

can you pls teach general theory of relativity

What actually bends...mass or energy??

What if everything is made out of light? Would gravity be generated by light displacing/interfering with/energising light at the speed of light squared?

Im not sure if anyone else got confused by this. But he is comparing point A) half mv squared vs point B) mgh. The kinetic at the beginning vs the potential at its highest point. What I don't understand is from rest the velocity would be 0 therefore making the kinetic energy 0. This equation only works if the object is already in motion right?