1

New Theories / Re: Do light particles have the mass density of black holes?

« on: 10/08/2024 15:35:36 »

Photons can never be at rest, they don't have any "rest mass", and c is not a valid inertial frame to which you can apply the Lorentz contraction.  That's three strikes right there.

2

Physics, Astronomy & Cosmology / Re: Does time dilation and length contraction apply to light?

« on: 07/04/2024 15:59:27 »

Krytptid's thoughts here mirror mine very closely and it seems I have a major gap in my understanding of SR(not surprising really). If one could travel at the speed of light surely one's rapidity would be infinite and hence time and space would have no existence- why does this not apply to light?. I have heard several physicists state that "light does not experience time or space" or something similar expressed more accurately: I cannot remember any names other than the mathematician Roger Penrose(who can be controversial at times). This question of mine is a bit muddled but I could not find a better wording. 

"If one could travel at the speed of light ..."  That's the issue.  Anything that travels at c would be in the same boat as light.
Consider the equation for relativist KE:
KE = mc^c (1/sqrt(1-v^2/c^2)-1)   if v=c, then it reduces to :
KE mc^2(1/0-1) 
Note the 1/0.  1/0 is undefined, thus the KE of a mass traveling at c would be undefined. Just like the singularity, the math doesn't give an answer for this scenario.
So when you post "If one could travel at the speed of light ...", you are essentially saying, "If Relativity doesn't hold..."

3

Chemistry / Re: What ingredients are in the withdrawn Takata airbags?

« on: 14/03/2024 14:48:59 »

The problem was that the airbags used phase stabilized Ammonia Nitrate, and that they did not include a desiccant.  Over time, humidity and high temps degraded the Ammonia Nitrate.  This led to it burning too quickly.  This, in turn, led to pressures inside the inflators beyond that which they could withstand, causing them to explode, spewing shrapnel.

4

Physics, Astronomy & Cosmology / Re: Would a gigantic stick out of neutronium bend around the Sun?

« on: 22/02/2024 16:47:16 »

This part I don't get (science is not my strong suit). I thought that space is bent around the star, so how can this stick defy space that is bent, even if equipped with EM field?

"Space-time" is said to be "curved".   In Relativity, space and time are not the separate and distinct things they were considered in Newtonian physics.  So, we have three spatial dimensions, Up-down, left-right, front-back. and a time dimension, past-future.  and they are all "connected" in a way.   

And saying that space-time is curved means that it doesn't adhere to the Euclidean rules of geometry.
Now, that being said, it is also important to remember that space-time is not some rigid structure that everything is fixed within. If that were the case, then movement would be impossible. Everything would be frozen in its point in space-time.
Nothing is "forced" to follow the local space-time curvature.  In can exert an influence, but it is not in insurmountable.  Local influences and forces can take precedent.
For example: The universe is expanding, and this is explained by space itself expanding. But this does not mean everything in the universe is expanding.  You are not expanding. Earth is not expanding, the solar system is not expanding, our galaxy is not expanding. This is because there are other influences (molecular forces, gravity) that hold these things in shape despite space itself expanding.

5

Physics, Astronomy & Cosmology / Re: If Andromeda is red shifted how can we collide with it?

« on: 28/01/2024 16:17:25 »

Andromeda is moving away from us as it is red shifted.  And yet we are going to collide with it. So how can we collide with an object that is red shifted?

It should be blue shifted if it is heading our way regardless of the universe expansion.

If the local gravity is overcoming the expansion and that is the explanation for our collision then how can it be red shifted when we observe it? 

(local dynamics, such as the gravitational interaction between the Milky Way and Andromeda, cannot explain why Andromeda's light appears redshifted if it is indeed moving towards us).

Andromeda is blue shifted.   It is part of our local group of galaxies which are gravitationally bound to each other.  The Universe is composed as a hierarchy of structures.  Star systems group together to form galaxies, individual galaxies form groups, groups form clusters...  It isn't until you get beyond the cluster stage that you begin to see the effects of the expansion.  So when it's said that the galaxies are receding from each other, it really means that structures that are formed from galaxies and are beyond a certain size are receding from each other.

6

Physics, Astronomy & Cosmology / Re: Has E=mc2 been proved practically?

« on: 09/12/2023 17:18:52 »

AC electricity moves at the speed of E/M light and is massless just like photons. So 50/60 cycle per second domestic electricity could  just be very low frequency E/M light. 
Further problem is particles cannot accelerate to light speed without a huge amount of energy being pumped in.
So we need to rethink how we visualise electricity and the parameters surrounding photons inside a conductor.

No, it doesn't.  The drift velocity of the electrons is really quite low, and even the effective speed ( like the time it takes between flipping a switch and the light coming on) can be as slow as 2/3c, depending on the conductor. 
Quite frankly, it sound like your objections to the present model for the conduction of electricity is based on a lack of knowledge of what the present model actually is.

7

Physics, Astronomy & Cosmology / Re: Why do the Earth's satellites orbit longer than the Moon's?

« on: 08/12/2023 17:01:02 »

I'm going to take a stab at what he might be getting at.
He may be talking about the stability of orbits around these two bodies.
If that is the case, then yes, low lunar orbits do tend to be less stable than low Earth orbits.
This is caused by mascons (mass concentrations)  randomly scattered under the Moon's surface. These are regions where the density is significantly higher than average, and this, in turn, tends to make the gravitational field nearer to the Moon a bit uneven which can disrupt the orbits of objects there.

8

Physics, Astronomy & Cosmology / Re: Has E=mc2 been proved practically?

« on: 08/12/2023 16:46:23 »

Electro-magnetic energy is fundamental energy has the formula = V*A *Cosineϴ*Time.
But if Cosineϴ is zero then even with volts and amps present we have no power energy only quantum power energy

That formula refers to  specific situation when you are dealing with an alternating current and a circuit with either capacitive or inductive reactance.  In such an instance, the voltage and current can be out of phase with each other, the difference in phase angle is what you are taking the cosine of to get effective  power usage of the circuit.  If the circuit were purely resistive, than there is no phase difference and you can just multiply volts times amp to get watts and then that by time to get energy usage.
 It has nothing to do with the "fundamental energy" of electromagnetic energy.

9

Question of the Week / Re: QotW - 23.11.17 - Why can't things travel faster than light?

« on: 11/11/2023 14:28:31 »

While the infinite energy argument is one way to explain it, it itself is a result of something more fundamental.
Relativity is really about the nature of time and space and their interrelationship.
It turns out that c is very instrumental  to this relationship.
Let's look at an example:
Ship A is accelerated up to 0.99c relative to its starting point.
Ship B is accelerated up to 0.99c relative to the same starting point, but in the opposite direction.
How fast are A and B moving relative to each other?
Prior to the advent of Relativity as a theory, we would have said both A and B would measure that they are moving 1.98c relative to each other.
Post Relativity gives us something else. We get an answer of 0.99979596...c for the speed either would say that the other was moving relative to themselves.
One issue the infinite energy answer has is that, unless you dig deeper into the theory. it can leave the reader with the idea that there is some absolute state of rest or reference for the universe that you can't move greater than c relative to.
This is not the case.
Let's change the above scenario a bit. Ship A, still travels off at 0.99c from the starting point.  But now it fires a projectile forward.  Nothing prevents him from firing that projectile at a speed of 0.99c relative to himself as he measures its speed.
However, someone back at the starting point will measure that projectile as moving at 0.99979596...c relative to himself, and Ship B would measure it to have a speed of 0.999998975...c
That projectile could fire a second projectile ahead of it at .99c, and everyone else would measure it as moving less than c.
It really doesn't matter whether you consider A, B, projectile 1, or projectile 2 as being "At rest", it's all the same.

10

General Science / Re: Is there a simple way to make fresh milk drinkable?

« on: 07/09/2023 18:34:52 »

AFAIK baby mammals drink milk direct from the source. This covers every species from laboratory mice to blue whales, including all apes. If you find the "fresh taste of the countryside" a bit overpowering, you could wipe the teat with alcohol.  Best get a friend to hold the head of the cow/sheep[/goat/horse if you are new to the game, and use a clean bucket.

Based on a fair amount of personal experience, it is generally not the head you need to worry about.

11

General Science / Re: Is there a simple way to make fresh milk drinkable?

« on: 06/09/2023 15:39:01 »

As someone who was basically raised on fresh (or raw) milk,  I'm a bit confused.  Why would you think that it is unsafe, in general, to drink?  As long as the animal that is milked is healthy and the milking conditions are clean, and the milk is refrigerated soon after milking, it is safe enough.
The big issue with raw milk is that, if left at ambient temp, it is a fertile breeding ground for pathogens.  If you are really worried about it, you can pasteurize it yourself, simply by heating it to ~100F for 20 minutes or so. 

12

Physics, Astronomy & Cosmology / Re: How do the fires in California manage to turn my Blue moon to red?

« on: 31/08/2023 16:08:49 »

Smoke particles scatter light, But the scattering is not even for all colors of light. Light at the red end is scattered the least.  You see a red moon because that is the light that managed to make the straight line trip from Moon to eye without being scattered.

13

New Theories / Re: How does Hamdani explain the twins paradox?

« on: 21/08/2023 17:48:17 »

It's seems to me that you are trying as hard as possible to Not understand Relativity.

It seems like that to you because you've been misunderstanding it without you realized.

What's the reading of the travelling clock by midway observer, one day before passing the mid point, and one day after passing it?

Outbound trip:
0ne day prior to ship arriving( by Midpoint's clock):

Actual time on ship clock: 32 days, 15 hrs, 34 min and 13.5718217858 sec.

What the Midpoint observer visually sees: The ship sitting at its planet of origin, waiting to depart.

One day after ship passes midpoint:

Actual time on ship:  32 days, 17 hrs, 42 min, and 59.490547741 sec

What the observer visually sees: 32 days, 17 hrs, 10 min, 48.9770892 sec

During return leg:


One day before: 
Actual time: 98 days 0 hr, 51 min, 26.63419131 sec

What is visually seen: The ship not quite having reached the turn around point, and a bit short of reading 65 days 9hr, 17 min, and 13.06236952 sec
One day after:
Actual time: 98 days 3 hrs, 0 min, 12.55291726 sec

What is visually seen: 98 days 2 hr, 28 min, and 12.5529176 sec.

14

New Theories / Re: How does Hamdani explain the twins paradox?

« on: 18/08/2023 16:53:15 »

To be consistent, let's use the speed used in Don Lincoln's video, which is 0.999c.
Here are the observations of those 5 key events as recorded by midway observer.
1. The journey starts on earth at t=0 local time. The light signal takes 2 years to the midway observer, thus he will see the event when his clock shows t=2 years. Journey from Alpha Centauri is the same due to symmetry.
2. The travelling twins take 2 ly / 0.999c = 2.002... year to get to the midway. Thus the observer will see his clock showing t=2.002... years.

During which time the midpoint observer will see the traveling twins' clock Doppler shifted by a factor of 44.710, and accumulating 44.710 * .002 = 0.089 yr, thus having their clocks each reading 0.089 yr upon reaching the midpoint.

3. The journeys take 4 ly / 0.999c = 4.004... year to get to the turning point in on going leg. But it takes additional 2 years for light signal to the midway observer, thus he will see the event when his clock shows t=6.004... years.

After each twin passes the midpoint, and are receding from it, the Midpoint observer will seeing them Doppler shifted by a factor of 0.0224, with each accumulating 4.004 * .0224 = 0.89 yr on their clocks to read 0.178 yr upon arrival at their destinations. (while the clocks at the destinations will read 6.004-2= 4,004 yrs)

4. The travelling twins take 6 ly / 0.999c = 6.006... years to get to the midway in return leg. Thus the observer will see his clock showing t=6.006... years.
5. The total journeys take 8 ly / 0.999c = 8.008... years to get home in return leg. But it takes additional 2 years for light signal to the midway observer, thus he will see the event when his clock shows t=10.008... years.

The return legs are just mirrored versions of the outbound legs, and give the same results, with an additional 1.79 yrs added to each twin's clock and 4.004 yrs added to the planets' clocks as seen by the midpoint observer.

15

New Theories / Re: How the Solar energy is created?

« on: 10/07/2023 16:11:19 »

That is perfectly OK
The oort cloud extends up to 3.2LY away from the Sun and sets the border of the solar system.
Therefore, it is very clear that even if we just focus on the 400 stars that are located up to 20 LY away from the sun (and ignore all the other millions that are located further away) we should discover that they set severe tidal heat forces on the Sun while each one works from different location.

Except that's not how any of this works.  Masses spread out surrounding the Solar system would cancel each other's tidal influences on the Sun out, they would not add up.  We see this same thing when the Sun and Moon are at right angles to each other in the sky. We get less intense tides as they work against each other.
In addition, tidal forces increase across the size of the region they are acting.  Therefore, tidal forces powerful enough to produce the type of heat energy the Sun outputs would rip the planets away from the Sun. The Sun's Hill sphere would be too small to allow for it to hold on to orbiting bodies

16

New Theories / Re: How does Hamdani explain the twins paradox?

« on: 23/05/2023 16:36:37 »

Time dilation is not a function of acceleration and there's no mathematical formula expressing it in terms of acceleration.

If acceleration has no effect on time dilation, then the observation of the accelerated twin should be equally valid as non-accelerated one.
Alternatively, there must be something else which makes their situations different, such as their relative motion against an external object, like CMB.

The observation of the accelerated twin is equally valid.   It is just that his observations are effected by his acceleration while he is actively accelerating. This includes clocks in the direction of the acceleration running fast compared to his own by a factor determined by the magnitude of the acceleration and the distance to the clock.
An analogy would something along these lines:
Two men are back to back and then separate. According to each of them, the other is a given distance "behind" him. Man 1 them turns 180 degrees.  By his perspective, Man 2 goes from being behind him to being in front of him.  As far as Man 2 is concerned Man 1 is still behind him, and this did not change when Man 1 turned around.  The observations of each is equally valid.
With Relativity, time is also involved, And "front" and "back" are replaced with temporal measurements. Acceleration involves a reorientation in space-time for the accelerated observer. 

17

Physics, Astronomy & Cosmology / Re: Can Light Experience 'Time'

« on: 14/05/2023 15:57:06 »

The key here is that it is "c" which is the important thing, not the light itself.  As far as we know, light in a vacuum travels at c.  But even if this turned out not to be the case, it would not change the importance of the speed c as an invariant speed. It would just mean that the photon is not the truly "massless" particle we now consider it to be. 

18

Physics, Astronomy & Cosmology / Re: Forgotten vocabulary - a thing being pulled apart by tidal forces.

« on: 07/04/2023 17:01:49 »

Hi.

    Well I was recently reading about the Large (and also the Small) Magellanic Cloud in our Milky Way.
As you may know, this object is thought to be a dwarf galaxy in its own right that has started to merge with our galaxy.   Anyway, it's falling in toward the centre of our galaxy due to what is called "friction", although its more like gravitational braking rather than anything like air resistance.    Very roughly speaking - as the cloud moves through diffuse gas at the outer edge of our galaxy, the gravity of the Large Magellanic Cloud (LMC) deflects gas particles from our Galaxy toward itself.   This will end up causing some increased density in the wake of where the cloud has been.   This over-dense region behind the LMC is then a source of gravity acting on the LMC and will effectively create a net braking force on it.    Finally, since the LMC is experiencing this net torque applied to it, it's losing angular momentum, the orbit is decaying and the LMC is sinking down to the centre of our galaxy.

    Now, the bit that was relevant is that while the LMC is sinking, it's also being stripped of its own gas.   So there won't be much of the LMC left as one big blob by the time it's near the centre of galaxy anyway.   I was just suspicious that the stripping process might be much the same as hitting the Roche Limit  - but it doesn't seem to be.
    The gas stripping is happening at a distance from the centre of our galaxy which is much larger than the Roche limit.  I'm not sure why, except that the  Small and Large magellanic clouds are very gassy (i.e. not at all solid or rigid) and thus easily shredded.   They just do seem to be breaking up in a significantly different way.   Unlike the thing described by @Halc  just a moment ago,  the LMC and SMC aren't breaking up in such a sudden and dramatic way.  I suppose they are just being stretched and deformed progressively.   Anyway, that's what was troubling me a bit yesterday - why aren't they just doing what we know about the Roche limit, presumably it is just that the objects aren't at all rigid.   The Roche limit never gets mentioned when discussing the stripping of gas from these things but it just does seem that they should be related.
   

gas trails.jpg (86.3 kB . 957x503 - viewed 2774 times)

   Image based on this source:   https://esahubble.org/news/heic1314/

Best Wishes.

This action seems to be a "Roche Lobe" effect : https://en.wikipedia.org/wiki/Roche_lobe

You get the same type of thing in some binary systems, where a white dwarf will siphon mass from its companion.  When enough mass accretes, you get a type Ia supernova.

19

Physics, Astronomy & Cosmology / Re: Will tidal power cause the moon to crash into us?

« on: 08/02/2023 16:48:59 »

Eventually, you'd expect Earth's rotation to slow down until a day was as long as a lunar orbit.

I think it is more likely that the earth would become tidally locked with the sun.

The tidal effect of the Moon on the Earth is roughly twice that of the Sun's, Tidal forces fall off by the cube of the distance, so even with its great mass disadvantage, the much closer distance to the Moon more than compensates.

20

Physics, Astronomy & Cosmology / Re: Why does this twin paradox thought experiment fail for me?

« on: 26/01/2023 15:57:12 »

instantaneous velocity change

I must take issue with anyone who uses this phrase!
For any body with nonzero mass, an instantaneous velocity change requires the input of a finite quantity of energy (½m(Δv)²) in zero time, i.e infinite power. This implies that the laws of physics have been suspended, including those of relativity and time dilation. The subsequent analysis is therefore invalid.
 

The issue with considering "instantaneous velocity change"   is that the magnitude of the acceleration becomes undefined.
v =at, so to find acceleration needed for a known change of v over a known period of t, you use a= v/t. but if t is zero, this is division by zero which is undefined. (not infinite).