Faster than light??? Nope!

[Chris Peterson]

Who is familiar with the investigation of the math regarding dark matter? If you take Newton’s equation F = ma and, for the sake of understanding, delete one of the variables, say mass, would it make any sense to consider with dark matter F = a ? Or perhaps m equaling a constant that is similar in galaxies with a known regular mass.

I know this is off topic but it came across my mind while reading these threads. After all, isn’t the force of gravity wh we are really missing and one of the main reasons we conclude dark matters existence?

No. The variable associated with dark matter is m. It has mass. It has gravity, which is how we infer its presence.

[neufer]

Click to play embedded YouTube video.

The variable associated with dark matter is m. It has mass.
It has gravity, which is how we infer its presence.

Hopefully (if dark matter is elementary)
it has a non zero weak hypercharge (Y_W) as well.

I need Y_W, Y_W, Y_W

[Ron-Astro Pharmacist]

Who is familiar with the investigation of the math regarding dark matter? If you take Newton’s equation F = ma and, for the sake of understanding, delete one of the variables, say mass, would it make any sense to consider with dark matter F = a ? Or perhaps m equaling a constant that is similar in galaxies with a known regular mass.

I know this is off topic but it came across my mind while reading these threads. After all, isn’t the force of gravity wh we are really missing and one of the main reasons we conclude dark matters existence?

No. The variable associated with dark matter is m. It has mass. It has gravity, which is how we infer its presence.

Of recent, the analysis the Bullet Cluster was proposed to be direct evidence dark matter. It showed the two colliding galaxies whose matter was gravitationally slowed but the baryonic matter continued on - if I recall correctly. It was quite interesting that the two could be separated and that which is associated with gravity is not with associated with the seen matter. Again I'm curious if there is a consistent correlation with the amount of known matter to the calculated amount of seen matter?

[neufer]

Of recent, the analysis the Bullet Cluster was proposed to be direct evidence dark matter. It showed the two colliding galaxies whose matter was gravitationally slowed but the baryonic matter continued on - if I recall correctly. It was quite interesting that the two could be separated and that which is associated with gravity is not with associated with the seen matter. Again I'm curious if there is a consistent correlation with the amount of known matter to the calculated amount of seen matter?

The gas was slowed (by collisions & magnetic entanglement) but the stars & dark matter both continued on.

Hence, there is not a consistent correlation with the amount of known matter to the calculated amount of seen matter.

<<"Particularly compelling results were inferred from the Chandra observations of the 'bullet cluster' by Markevitch et al. (2004) and Clowe et al. (2004). Those authors report that the cluster is undergoing a high-velocity (around 4500 km/s) merger, evident from the spatial distribution of the hot, X-ray emitting gas, but this gas lags behind the subcluster galaxies. Furthermore, the dark matter clump, revealed by the weak-lensing map, is coincident with the collisionless galaxies, but lies ahead of the collisional gas. This—and other similar observations—allow good limits on the cross-section of the self-interaction of dark matter.">>

[Beyond]

Photons May Emit Faster-Than-Light Particles, Physicists Suggest.
http://www.livescience.com/38533-photon ... icles.html

[neufer]

Photons May Emit Faster-Than-Light Particles, Physicists Suggest.
http://www.livescience.com/38533-photon ... icles.html

This means that if photons live for 1 quintillion years, from their perspective, they will only live about three years.

Such an unstable photon has a relativistic Lorentz factor:

> 3 x 10¹⁷

This photon would lag behind a mass-less particle
by just 5cm after 1 quintillion year lifetime

[Beyond]

That photon formula is way too bright for me to be able to see any meaning to it.

[Chris Peterson]

That photon formula is way too bright for me to be able to see any meaning to it. :yes: :lol2:

The take home message is that if there are particles that travel faster than photons, it isn't by much. We'd need to work out a new value for c, which would increase by a few billionths of billionths of a percent. From a practical sense, it wouldn't allow us to communicate or travel any faster.

[neufer]

That photon formula is way too bright for me to be able to see any meaning to it.

The take home message is that if there are particles that travel faster than photons, it isn't by much. We'd need to work out a new value for c, which would increase by a few billionths of billionths of a percent. From a practical sense, it wouldn't allow us to communicate or travel any faster.

It should also be pointed out that:

• 0) Cosmic rays already exceed the speed of light in air.
  
  1) Almost all neutrinos (i.e., of energies >5 eV) exceed the speed of light in air.
  
  2) Neutrinos of energies >100 TeV exceed the speed of light even in the vacuum of space