Neil Degrasse on divine properties.

originally posted by: Grenade
a reply to: chr0naut

I don't think that answers my question.

Apologies. Your specific question was how a photon could have less mass, if it is massless.

The answer is that a photon has zero at-rest mass, but there is no such thing as a photon at rest. All photon's must necessarily be moving, and that speed must close to the constant 'c' (approximately the speed of light). The propagation speed of light is variable, but 'c' is not.

We know that there is an equivalence between mass and energy, and so energy relates to mass multiplied by the square of the constant 'c'. This also means that mass equals energy over the square of the constant 'c'. In this way anything with energy always has mass.

A lower mass photon would probably be traveling slower than at the velocity 'c', but I am unclear if such a thing exists.

a reply to: chr0naut

What lighter elements could it decay into in such a scenario? I’m genuinely interested.

originally posted by: Grenade
a reply to: chr0naut

What lighter elements could it decay into in such a scenario? I’m genuinely interested.

Most likely, it would be a lower mass photon, i.e: traveling at sub 'c' velocity.

Or, according to Quantum Chromodynamic (QCD) theory, and somewhat verified in photon-electron and photon-proton scattering experiments, it could, through interaction with an electron, break down into its internal components of quark and antiquark pairs (the number of pairs relating to momentum).

originally posted by: Untun
The relativity of Einstein: The faster you move the slower time ticks for you relative to the observer.

5:00 When you go the speed of light you will watch the whole future history of the universe unfold in front of your eyes.
For you, your time has slowed to the point where as you observe the things that are not moving at the speed of light, you see them unfold.

- Light sees everything, therefore knows everything when it has good memory.

7:30 and further: Travelling at the speed of light there is no time. Light can travel across the universe and not age.

- Light is eternal.

So far I can conclude that something eternal exists, possibly knowing everything and if this light is conscious, as it sees everything unfold it could imagine itself to be the creator of everything.

What you posted in your OP doesn't sound anything like what Tyson is saying in the video, to me.

originally posted by: namehere
no light is not eternal, light is like all other forms of electromagnetic radiation, it decays into heat then that heat decays into either a form we cant measure or is destroyed forever.

I don't know what crackerjack box you got that prize in, but it seems like light from distant galaxies just keeps going if it doesn't run into anything. As space seems to be expanding, the light gets "red shifted" but the energy reduction is not due to decaying into heat, it's due to being spread out over a larger space-time.

originally posted by: Grenade
a reply to: namehere

If a photon has no mass then how can it decay into a lighter element? Consider the origins and definitions of the word lighter.

The life of a photon

From our reference frame:

That's a lot longer than the entire age of the universe.

That's theoretical physics, where we can guess what happens at ages longer than the age of the universe, and nobody can prove us wrong, because nobody has observations that far in the future.

But closer to observable reality, photons don't need mass to decay, they just need more energy than the equivalent masses of the particles they change into, as in pair production.

Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus. As energy must be conserved, for pair production to occur, the incoming energy of the photon must be above a threshold of at least the total rest mass energy of the two particles created.

originally posted by: Grenade
a reply to: chr0naut

What lighter elements could it decay into in such a scenario? I’m genuinely interested.

In the example of pair production, the electron and positron resulting from the photon are not elements, they are subatomic particles.
In the theoretical physics reference you posted, a decay product mentioned is possibly a neutrino and some other as yet not known particle. Neutrinos don't have much mass, so little that at one point we thought they didn't have any mass. Their mass is so small it's hard to measure.

originally posted by: chr0naut

originally posted by: Grenade
a reply to: chr0naut

I don't think that answers my question.

Apologies. Your specific question was how a photon could have less mass, if it is massless.

The answer is that a photon has zero at-rest mass, but there is no such thing as a photon at rest. All photon's must necessarily be moving, and that speed must close to the constant 'c' (approximately the speed of light). The propagation speed of light is variable, but 'c' is not.

We know that there is an equivalence between mass and energy, and so energy relates to mass multiplied by the square of the constant 'c'. This also means that mass equals energy over the square of the constant 'c'. In this way anything with energy always has mass.

A lower mass photon would probably be traveling slower than at the velocity 'c', but I am unclear if such a thing exists.

1) What?
2) No just no

You are throwing together things that are not at all true to make a layman's explanation for something that simply isn't a thing.

Photons do not have mass... period.

If you are talking about E=MC^2 then how many times do i have to say it... THAT EQUATION IS A CONTRACTION, its wrong, the actual equation used in relativity, is

E^2=P^2C^2 + M^2C^4

Photons have Zero mass... but they do have momentum, P so their energy is directly related to their momentum.

E=PC in this case. P = h/Lambda and boom
E=h/lambda C

relating wavelength to energy.

Also when people talk about light slowing down when passing through materials... it is the phase velocity that slows down, not the fundamental speed of light.

So the phase velocity which is the propagation of the wavegroup slows in a material, but the speed of light doesn't change.
In the high energy region above X-Rays some materials have refractive indexes of less than 1, which would mean the photon can break the speed of light and travel super luminal... except... no it doesn't its never been observed because as i say, its not the speed of the particle but the wavefront/group that changes.

Also Degrasse wasn;t the one who said "Pluto, sorry you are not a planet" it was done by consensus with thousands of people.

If pluto is a planet, then we have to increase the number of planets in the solar system to about 20-100 depending on where you put the size cutoff if thats your idea.

The only reason people hold onto it so much is because its was the first 'planet' discovered by an American astronomer and Americans seem to attach some kind of weird national pride to absolutely every single aspect they are involved in.

Not a planet by any astronomical definition... is a very interesting object, as are its neighbours in the Kuiper Belt

a reply to: ErosA433
I gritted my teeth when I saw that post but I do give him at least some credit for saying "but I am unclear if such a thing exists." Thanks for confirming it doesn't, certainly not in a vacuum and as you inferred the way light travels through materials like glass involves phonons, quantum mechanics and is rather complicated.

Also Degrasse wasn;t the one who said "Pluto, sorry you are not a planet" it was done by consensus with thousands of people.

Yes that's sort of correct in that there was a vote in 2006 that officially demoted Pluto. However, there's more to the story.

Before that vote, Tyson had already demoted Pluto by 2000, in his role as director of the Hayden planetarium part of the American Museum of Natural History. He was getting hate mail from museum visitors including children telling him he screwed up by not showing Pluto as a planet. So I think he takes responsibility for that demotion at the museum without any help from the folks who voted on it 6 years later. It's almost become a meme in popular media as this 2 minute clip shows of physicists attending a conference where one of the actors playing a physicist accuses Neil Tyson of making kids cry by demoting Pluto:



So Tyson doesn't deny demoting Pluto personally, it just wasn't official in 2000 like it became in 2006. (It sure looks like physicists are living large at that extravagant (fictional) conference).

Tyson says the person really responsible for Pluto's demotion is Mike Brown known as "PlutoKiller" on twitter, who discovered other objects like Pluto that eventually forced the vote and there was really only one logical outcome for the vote.

'Pluto Had It Coming' Says Neil deGrasse Tyson

I stand corrected haha... but yeah one person, as high profile as he might be, altering it in a museum isn't really the same as actual scientific consensus but, yep i can now see the history of the beef with it haha.


But yeah thats the thing with science it refines its view and evolves. Whats also interesting is that in the grand scheme of things, pluto being a planet or a dwarf planet means... nothing... it does however give it a clear classification that it is an object with different properties to the rest of the main planets, which it absolutely does have.

Does it make the object any less interesting? nope, its just as interesting... id love a probe to make it out there and take a orbit that keeps it in the belt and have the possibility of catching up to or seeing some other of these objects... why? because science haha

sounds like he needs
a good degrasse
kicking.

originally posted by: ErosA433
Does it make the object any less interesting? nope, its just as interesting... id love a probe to make it out there and take a orbit that keeps it in the belt and have the possibility of catching up to or seeing some other of these objects... why? because science haha

I agree, Pluto is very interesting and I think Neil Tyson would agree with that, even though he demoted it. The probe we did send to Pluto showed it and its partner Charon are far more interesting than I would have guessed before we sent the probe.

solarsystem.nasa.gov.../dwarf-planets_pluto


www.universetoday.com...

So many interesting patterns and mysteries to solve.

a reply to: sarahvital
I did learn one thing from this thread. I never realized there were so many Neil DeGrasse Tyson haters out there, but based on the comments in this thread and in the youtube comments section for the video, it's apparent that quite a number of people don't like his self-confidence and lack of humility. From my perpective it's good to have humility if you're discussing a subject you don't know much about and I think even Tyson shows that when he talks about subjects he's not knowledgeable about, but when talking about subjects he knows quite well, I don't see why he should have to show false humility.

I thought Carl Sagan was a great science communicator, who was an inspiration to Neil Tyson who also strives to be a good science communicator. They both did versions of Cosmos TV series, and I think Sagan's version was better, but I think my disappointment with Tyson's version had more to do with some of the writers for the show than with Tyson.