The Naked Scientists

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1
will voyager have collected mass due to its own gravity as it passes through dust?
could this lead one day to planet voyager. ;-)
Voyager will need a very long time indeed to acquire enough mass to be assigned that title. In fact, the universe will probably die the forecasted heat death before that remote eventuality occurs.
Sometime Voyager could smack into a planet, star, black hole, comet, or such.  Or, perhaps end up in an accretion disk. 

Phenomena such as the Asteroid Belt, Kuiper Belt, Oort Cloud, and such have far lower density than one might expect from watching Hollywood movies.  However, a few billion years in the future, I find it doubtful that we'll have two perfectly intact space ships quietly floating through the universe, and the Voyager probes may well be incorporated into a much larger objects.
2
We also have the following public declarations from astronauts:

Major Gordon Cooper
Donald Slayton
Major Robert White
Joseph A. Walker
Commander Eugene Cernan
Ed White & James McDivitt
James Lovell and Frank Borman
Neil Armstrong & Edwin Aldrin
Maurice Chatelain
Scott Carpenter

They all claim to have seen UFOs which they believe to be from another world. Many of them are National heroes (Neil Armstrong was the first person to walk on the moon).

It seems crazy to think that there is some sort of alien coverup, but I personally have seen quite a few UFOs over my home town (White pulsating orbs hovering slowly, completely silent, changing direction then disappearing over Jersey, Channel Islands). We don't have experimental craft where I live. We don't even have a military. I just think it is a matter of time before public knowledge gets turned upside down and we realize that we aren't the big fish in the universe anymore.
3
Geek Speak / Re: Using a digital camera as a webcam
« Last post by nicephotog on Today at 07:14:19 »
Because of data congestion over the net it helps if you are using live streaming to use no more than 800 x 600 web cam. Larger cameras can cause freeze and trouble in the receivers' software.
4
Physics, Astronomy & Cosmology / Re: black holes soft centered?
« Last post by evan_au on Today at 05:54:48 »
Quote
the gravity inside the black hole would become zero at its centre, being a perfect sphere.

This would be true if the black hole were a solid sphere, like the Moon. As you approach the center of the Moon, the gravitational force (or the weight of an object) would approach zero. So if you did manage to tunnel to the center of the Moon without getting crushed, you would be able to float weightless.

We don't really know what is inside a black hole. However, we know of nothing that can withstand the crushing gravity of a black hole. So the black hole cannot be a solid sphere like the Moon. Matter crossing the event horizon is already travelling at a significant fraction of the speed of light. At this speed, it would not take very long to reach the center of the black hole - perhaps a second for a stellar-sized black hole, or less than a day for a black hole the size of our galactic black hole.

This suggests that a black hole is mostly empty space, with most of the matter concentrated at the center. So rather than finding a serene zone of weightlessness at the center where you could float without concern, you would smash at immense speed into a zone with extreme tidal forces that would tear you apart ("spaghettify" is the technical term).

Quote
why do all black holes not have the same mass?
The mass of a black hole is determined by how much matter it contains.

If a black hole is formed from the collapse of a small star, it will have less mass than a black hole formed by the collapse of a larger star.

A black hole at the center of a large galaxy has sucked in many stars, and has more mass than the black hole at the heart of a smaller galaxy, which has consumed a smaller number of stars.

Quote
why do all black holes not have the same mass, gravitational pull and event horizon size?
A more massive black hole will have a larger gravity, because it has more mass.

A more massive black hole will have a larger event horizon, because the escape velocity from this larger mass will exceed the speed of light further from the center of the black hole. The escape velocity reaching the speed of light is one constraint on the zone from which light cannot escape. There are other constraints on the escape of matter, some of which are affected by the spin of the black hole.
5
causes of itchy skin which isn't visibly abnormal include formication
Really in RD shapes?

Formication can be general or just in certain areas, depending on the cause.

To feel ultrasound you'd need two ultrasound sources in line-of-sight, operating at slightly different frequencies so generating a lower beats frequency , low enough to be felt. 

BTW here's the cheapest [new] ultrasonic detector I can find ...
http://www.amazon.co.uk/Discovery-Channel-D12-Ultrasonic-Detector/dp/B00DUNS8K8
It's a toy but apparently it does work and you could conduct experiments to see if you are being bombarded with ultrasound, (which you are not) , and find out if ultrasound can penetrate walls & windows.

You arent attempting to answer.
Bro I already got a positive ultrasonic read out.
6
Just Chat ! / Re: Punning is hard(ly) work! Groaning aloud here?
« Last post by demografx on Today at 05:06:06 »
Its quite, the BUNNY situation when you think about it , but I am ever so happy to say that it always comes out in the END! XXX

Q. D you know how to catch a unique bunny?

A. Unique up on it

Q. Do you know how to catch a tame bunny?

A. Tame way!
7
Physics, Astronomy & Cosmology / Re: black holes soft centered?
« Last post by PmbPhy on Today at 04:32:21 »
Quote from: barneyboy
if black holes have/are a singularity of r=0, infinite gravity and matter compressed out of existence, why do all black holes not have the same mass, gravitational pull and event horizon size?
I don't understand your question. Why do you think they should have the same mass? Even in Newtonian gravity that would be wrong. Do you know Newton's theory of gravity? It states that if you have a point object of mass M and another point object of mass m then the force magnitude of the force between the two objects is given by

F = GMm/r2

Suppose that M is much greater than m (i.e. M >> m). The force on the second object is F = ma. In this case the acceleration is the acceleration due to gravity wherein we represent a using the letter g, i..e a = g. Then

F = mg = GMm/r2

Cancel out m to get

g = GM/r2

This is the value of the gravitational field at the point r. Notice how it depends on the value of M regardless of it's value and notice also that it's a point object. So why would you think this has to be different for a black hole? Note that the gravitational field far from the black hole has the value g = GM/r2

Quote from: barneyboy
if they do not compress matter out of existence
No matter can be compressed out of existence.

Quote from: barneyboy
they would grow with all the matter they consume but this would mean that the gravity inside the black hole would become zero at its centre, being a perfect sphere.
That's not true. At the center the value is undefined (i.e. infinite), not zero. Why do you think it's zero?
8
Technology / Re: Who stole my camera?
« Last post by evan_au on Today at 03:39:30 »
Some sites delete the EXIF data to save a bit of storage/download size, or to protect the privacy of people posting photos (some cameras include the GPS coordinates where the photo was taken).
9
New Theories / Re: Lambert's Cosine Law
« Last post by jeffreyH on Today at 03:18:47 »
Having the Planck area lP^2 in the equation is of interest.

http://en.wikipedia.org/wiki/Planck_length
"The Planck area, equal to the square of the Planck length, plays a role in black hole entropy. The value of this entropy, in units of the Boltzmann constant, is known to be given by A/4lP^2, where A is the area of the event horizon. The Planck area is the area by which a spherical black hole increases when the black hole swallows one bit of information, as was proven by Jacob Bekenstein."

The term lP^2/r^2 can therefore link our mass-energy to a density function that relates to the horizon black hole.

Another important point on this page is this.
"In doubly special relativity, the Planck length is observer-invariant."
So is length contraction valid or are space and time separate.
10
causes of itchy skin which isn't visibly abnormal include formication
Really in RD shapes?

Formication can be general or just in certain areas, depending on the cause.

To feel ultrasound you'd need two ultrasound sources in line-of-sight, operating at slightly different frequencies so generating a lower beats frequency , low enough to be felt. 

BTW here's the cheapest [new] ultrasonic detector I can find ...
http://www.amazon.co.uk/Discovery-Channel-D12-Ultrasonic-Detector/dp/B00DUNS8K8
It's a toy but apparently it does work and you could conduct experiments to see if you are being bombarded with ultrasound, (which you are not) , and find out if ultrasound can penetrate walls & windows.

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