Before we can understand the “secret” of the pulsars, it is necessary to understand what a pulsar actually “is”.
There are 2 steps to this understanding:
- Being able to understand what a neutron star “is”.
- Understanding when a neutron star becomes a “pulsar”.
What is a neutron star?
In order to conceptualize a neutron star, we can start by looking at a normal star, such as the Sun, and compare that to a neutron star.
The following are a couple of values describing the size and weight of the Sun:
- The Sun is approximately 1 million miles in diameter (~864,500 miles).
- The mass (weight) of the Sun is 2×10**30 kilograms
(where 2×10**30 = 2 times 10 to the 30th power (1 with 30 zeroes)
( which is 330,000 times the mass of the Earth )
( 1 kilogram = 2 1/2 pounds)
The following are the corresponding values for a neutron star:
- A neutron star is approximately 20 miles in diameter.
- A neutron star weighs approximately 2.8×10**30 kilograms
(i.e. 1.4 times the mass of the Sun)
Therefore, to imagine a neutron star (ns), one can imagine all the material that comprises the Sun in a 432,000 mile radius sphere, compressed into a 10 mile radius sphere.
Since the same mass is compressed into a sphere that is 40,000 times smaller radius than the Sun, the “density” of the material goes as the cube (power of 3), which implies the density of a neutron star is 64,000,000,000,000 = 64 trillion times as dense as the Sun.
And, actually since the ns mass is 1.4 times the Sun mass, one needs to stuff an extra 1/2 of the Sun’s mass into that 10 mile radius sphere as well.To bring things closer to reality let’s calculate what one cubic foot of neutron star material weighs:
- Volume of 10 mile radius sphere = 4/3 x 3.14 x 10 **3 cubic miles = 4,000 cubic miles.
- 1 cubic mile = 5,000**3 cubic ft = 125,000,000,000 = 125 billion cubic feet.
- so, vol ns = 4,000 x 125 billion cu-ft = 500,000 billion cu-ft.
- so density of ns = 3×10**30 kilograms / 5×10**14 cu-ft = 0.6 x 10**16 kg/cu-ft
= 1×10**16 pounds/cu-ft
- i.e. 1 cubic foot of ns material weighs 10**16 pounds = 100 quadrillion pounds
Since the Earth is 1/330,000 times the weight of the Sun, the whole planet Earth would approximately be stuffed into a 1 billion cubic foot container. This can be visualized as a cube, 1,000 feet on a side.
If we assume a football stadium is 100 feet high, and roughly 1,000 feet long and 500 feet wide (including the stands plus the field), then a football stadium has a volume of about 500,000×100 cubic feet = 50 million cubic feet.
Therefore, if the Earth were compressed to the density of a neutron star, then the whole Earth would fit in about 20 football stadiums.
Since the Moon is about 1/100 mass of the Earth, it would fit in 500,000 cu-ft, or a cube about 80 feet on a side. i.e. it would fit in the middle of the football field inside the football stadium.
Pretty heavy stuff.
Therefore, a neutron star “is” a sphere containing about 1 and a half times the mass of the Sun, where the radius of the sphere is about 10 miles.
In order to compress material to the density required for a neutron star, the atoms themselves will be crushed, so that the electrons that surround the atom’s nucleus are actually forced into the nucleus, itself, which means all the protons, each with a “+” charge will be combined with all the electrons, each with a “-” charge, which will make each electron-proton pair an uncharged neutron.
The compression effectively turns all the mass of the neutron star into uncharged neutrons, which actually means that a neutron star is one giant atomic nucleus comprised of an unfathomable number of neutrons.
Such an object seems like a concept out of science fiction. On Earth, lone neutrons are unstable and immediately decompose into an electron and a proton, which are the components of a hydrogen atom. A hydrogen bomb explodes by combining pairs of hydrogen atoms into deuterium which initially contains 2 electrons and 2 protons:
Fusion in stars
So, even if we were able to produce a tiny amount of neutron star material on Earth, it would instantly explode with a force comparable to that of an H-bomb.
Why doesn’t a neutron star explode?
Because the gravity of all the neutrons together is so strong that the neutrons are unable to decay into proton-electron pairs, as they would instantly be fused back together.So, …
What is a pulsar?
A pulsar “is” a neutron star.
But, it is a neutron star that is behaving in a particular way.
Note that if there was a neutron star somewhere nearby, say the distance to the closest visible star, which is approximately 4 light years away from us here on Earth, it is just a 1.4 solar mass ball that is 10 miles in radius and does not shine or anything like that. i.e. we would not “see” it. The neutron star would just be a dark ball way out in space that we would have no chance of seeing even with today’s most powerful telescopes.
On the other hand we can and do see “pulsars” that are thousands of light years away from the Earth.
So, how are we able to see pulsars, which actually are neutron stars?
i.e. what is it about a neutron star that makes it a “pulsar” that we can “see”?
“Pulses” are bursts of energy that a pulsar regularly emits, at a specific periodic rate. The fact that the time between pulses is slowing down (getting longer) from an isolated pulsar, means that it will eventually use up all its pulsation energy and no longer emit pulses.
So, the question becomes: “Where does the neutron star get the energy that it uses to emit pulses?”.
The first thing that distinguishes pulsars from anything else is that they “pulse”.
i.e. when we “see” a pulsar, we “see” the pulses that it emits.
It also turns out that because pulsars are capable of pulsing at 30 times per second or more, that they must be neutron stars, as was discovered with the Crab Pulsar in 1968:
Note: while the above reference gives a good description of what a pulsar “is”,
this site is in complete disagreement with the above reference’s claim that:
a pulsar is created by a supernova explosion. (i.e. this stmt is false)
In fact, this site will show that quite the opposite is true:
i.e. that the pulsar causes the supernova explosion (i.e. this stmt is true)
Based on the pulse frequency of the Crab Pulsar and the intensity of the pulses it emits, it is necessary that the Crab Pulsar must be a neutron star, and from this we conclude that all pulsars must be neutron stars:
(Note: there is speculation that some pulsars may be white dwarfs, however, as will be shown on this site, it is very unlikely that white dwarfs are connected in any way to the actual objects that are currently recognized to be pulsars, except by being a companion to the actual pulsar. i.e. it will be shown that pulsars can turn regular stars into white dwarfs, as is the case with milli-second pulsars, but the white dwarfs are not, themselves, pulsars.)
Continuing with what a pulsar “is”, we need to next understand what it is that is actually “pulsing”. As described earlier, it is only by observation of these pulses, that we know that neutron stars exist, and we also know that all by itself a neutron star does not pulse, it simply exists as a dark sphere in space completely unobservable.
It is not currently understood exactly what the origin of the magnetic field within a neutron star is, however, it must be related to some sort of alignment of the neutrons, themselves, such that their magnetic fields are parallel, at least within some section of the neutron star:
Neutron Star Magnetic Field Origins
Neutron Star Magnetic Fields
Therefore, a neutron star, all by itself has a very large intrinsic magnetic field. If this field is aligned with the rotation axis, then no radiation will be emitted. However, if the magnetic field is aligned at some angle, possibly even perpendicular, to the rotation axis, then the neutron star will emit electromagnetic waves, of relatively low energy in the radio spectrum.
Therefore, a “pulsar” is a rotating neutron star that has a magnetic field that is aligned at some non-zero angle with respect to the neutron star’s rotation axis. This mis-alignment causes radio pulses to be emitted by this rotating object that can be observed with radio telescopes here on Earth.
i.e. in other words: a neutron star “becomes” a pulsar when its magnetic field is misaligned with its rotation axis.
However, as we know from conservation of energy, the energy emitted by the radio pulses must take away energy from the rotating object. That energy taken away will be in the form of a “slowing down” of the rotation rate. Eventually, on the order of millions of years, the rotation rate will become so slow that pulses will no longer be observable, and the pulsar will effectively disappear.
So, now, from the above discussion, we “know” what pulsars actually are (rotating neutron stars, with magnetic fields aligned at non-zero angle to rotation axis), and that in the course of time, that they will disappear, by losing energy emitted by radio pulses from the changing magnetic field resulting from the mis-alignment.
So, the question now arises, where do these pulsars come from in the first place?
This is where the fun really begins, and this site will take the reader on a journey to a completely new understanding of supernovae, pulsars, neutron stars, and dark matter. From there the journey will continue to a completely new understanding of the galaxy and possibly the universe itself. Also, this journey will be found to be inescapable, in the sense that no other explanation currently exists to account for the observations that have been made of pulsars.
Another conceptual pulsar model
Consider a big ball with a long pipe extending out of each pole (the north and south poles).
Now consider that the big ball is a giant vacuum cleaner that can suck matter in through the two pipes.
If this ball is floating through space and encounters a star, when it comes close to the star one of the poles will hit the atmosphere of the star and start to suck in matter from the star. This is like a “whack” to the pole and will cause the big ball to start to spin.
The second pole will then shortly also get whacked by hitting the star and cause the ball to spin faster, causing the first pole to get hit by the star again and so on.
From this model we can see roughly how a spinning pulsar is created by encountering a star. It would never have started spinning without the encounter.
Finally, to complete the model, when the pulsar is really spinning fast, let us consider that the matter being sucked in along the poles is then ejected from the pulsar along the spin axis.
The result of this latter scheme is that the matter falling in adds to the angular momentum of the pulsar, while the matter being ejected does not cause a loss of angular momentum because it is being ejected along the spin axis. i.e. this process adds angular momentum to the pulsar without adding matter to the pulsar since everything that is sucked in is also ejected out.