Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 19/10/2012 03:30:02
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David Michaels asked the Naked Scientists:
Hi Naked Scientists,
I have listened to pretty much all your podcasts (http://www.thenakedscientists.com/HTML/podcasts/), and have built up a lot of dumb questions, and knowing the only dumb question is the one not asked, I have loaded up. (I apologize if any of these have been covered, or if I should have figured them out .)
First of all we all wonder how a show that is supposed to be accurate does not have really naked scientists, (but being radio, we can't be sure)...
If mass increases as you approach the speed of light why are most objects that travel at that speed almost massless?
What if you by definition, call the speed of light 0 m/sec., wouldn't it make more sense, as objects slow down, they should get heavier? If c were defined as zero, would you be able to say we are really moving through the aether?
Great show (http://www.thenakedscientists.com/HTML/podcasts/), I wouldn't change a thing (except for having really naked scientists).
Regards,
Dave
What do you think?
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So called gravitational mass does not increase at speed.Photon has "repellent" mass.
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So called gravitational mass does not increase at speed.Photon has "repellent" mass.
Photons have inertia not mass. E=Mc^2 + pv the pv represents the photon inertia = hf
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If mass increases as you approach the speed of light why are most objects that travel at that speed almost massless?
Their mass doesn't increase because they have no mass to start with, so there is nothing to increase.
OK, that's an oversimplification, but why complicate things?
BTW, I know of nothing that is "almost massless" that travels at c.
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BTW, I know of nothing that is "almost massless" that travels at c
Neutrinos come close
https://www.newscientist.com/article/dn21899-neutrinos-dont-outpace-light-but-they-do-shape-shift/
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Coming close is not quite the same thing.
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Coming close is not quite the same thing.
Very True
Do you have a take on entanglement and none locality where it is claimed by some information transfer is in excess of c. https://arxiv.org/ftp/arxiv/papers/1402/1402.4764.pdf
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Does mass increase?
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I do have a "take" on entanglement and none locality, but it would be way off topic in this thread.
I've not read the article properly, yet, but one thing jumps out:
"Just prior to the measurement, however, the quantum
potential of both particles is affected by the measuring
system for example of particle 1. Therefore particle 2 being
part of the overall quantum system is informed of the
imminent act of the particular measurement of particle 1".
Assuming that particle 2 is "informed" may be using "non-quantum" language to try to describe a quantum situation.
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Does mass increase?
I suspect, not, but it may depend on how you define mass.
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Does mass increase?
If there is no mass in the first place, mass can not increase. the energy of a photon however can increase or decrease in a gravitational field, depending on which way it is travelling.
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I do have a "take" on entanglement and none locality, but it would be way off topic in this thread.
Understood, I tried starting a thread including this on what space is but it has been hijacked at the moment.
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So called gravitational mass does not increase at speed.Photon has "repellent" mass.
The problem here is that different people are using different definitions of mass. You're using the definition where mass = proper mass. Not everyone does so, such as me and the following author
Measuring the active gravitational mass of a moving object by D. W. Olson and R. C. Guarino, Am. J. Phys.[/b] 53, 661 (1985); https://aapt.scitation.org/doi/abs/10.1119/1.14280
Abstract
If a heavy object with rest mass M moves past you with a velocity comparable to the speed of light, you will be attracted gravitationally towards its path as though it had an increased mass. If the relativistic increase in active gravitational mass is measured by the transverse (and longitudinal) velocities which such a moving mass induces in test particles initially at rest near its path, then we find, with this definition, that Mrel=γ(1+β2)M. Therefore, in the ultra relativistic limit, the active gravitational mass of a moving body, measured in this way, is not γM but is approximately 2γM.
Alan Guth provides the following argument
http://www.newenglandphysics.org/common_misconceptions/Alan_Guth_01.mp4
I provide an argument here: https://arxiv.org/abs/0709.0687
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I would advise taking note of what pmbphy has to say.
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I would advise taking note of what pmbphy has to say.
Gee whiz. That's very generous of you to say. I hope I can live up to it. :)
Here's a page from Alan Guth's lecture notes where he says that since light has energy it effectively has mass: www.newenglandphysics.org/other/guth.jpg
Also, since light has momentum it really does mean that it has mass. That's a fact used in the SR text used to teach special relativity at MIT. By mass they mean relativistic mass whereas the mass the gentleman speaks of above mean proper mass.
In fact the expression for momentum in SR is derived using conservation of the quantity Mv. What M comes out to mean depends on what one wishes to us to define mass.
Did I mention why I hesitated in helping more in the past. There's a freak out there who stalked me on the internet and too every effort to prevent me from correcting him. That nut job even went out of his way to create this:
He even ignored the fact that I wasn't alone in what I said. One authority on relativity I've known for 20 years wrote a book called Einstein's Mistakes. His name is Hans C. Ohanian. Here's the relevant part of his book which explains it:
http://www.newenglandphysics.org/other/Ohanians_Third_Mistake.pdf
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I wish to check something I read ref quantum gravity, and would like to ask an embarrassing question ref the speed of light.
It is normally accepted that the speed of light is constant in a vacuum, but may slow down if travelling through matter. Matter is made up fields, can an electrical or gravitational field slow the speed of light down in a vacuum.
The following link suggests the speed of light is not so constant in a vacuum, is it pop science or are they correct.
https://www.sciencenews.org/article/speed-light-not-so-constant-after-all
The version of quantum gravity I have just ploughed through suggests that light speed may be affected by gravity could it be correct.
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I wish to check something I read ref quantum gravity, and would like to ask an embarrassing question ref the speed of light.
It is normally accepted that the speed of light is constant in a vacuum, but may slow down if travelling through matter. Matter is made up fields, can an electrical or gravitational field slow the speed of light down in a vacuum.
The following link suggests the speed of light is not so constant in a vacuum, is it pop science or are they correct.
https://www.sciencenews.org/article/speed-light-not-so-constant-after-all
The version of quantum gravity I have just ploughed through suggests that light speed may be affected by gravity could it be correct.
That article suggests that its something new when actually Einstein predicted the slowing of ight in a gravitational field in 1907. He used that to derive the actual being of light by the sun.
It was experimentally verified by Harvard physicist in the 60's. He stated that the slowing of light in a g-field is one of the predictions of GR.
By the way. The claim that relativistic mass is not used by serious physicists is wrong. They teach it at Harvard. See:
https://aapt.scitation.org/doi/10.1119/1.17870
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It was experimentally verified by Harvard physicist in the 60's. He stated that the slowing of light in a g-field is one of the predictions of GR.
This is an off topic quick question. BUT from a photons perspective travelling through space time does time exist or is it stationery, also does space exist for a photon travelling at light speed. ?
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This is an off topic quick question. BUT from a photons perspective travelling through space time does time exist or is it stationery, also does space exist for a photon travelling at light speed. ?
Time and space still exist because it takes time for the light to travel a distance, but from the photon’s viewpoint both time and distance are dilated/contracted to 0.
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This is an off topic quick question. BUT from a photons perspective travelling through space time does time exist or is it stationery, also does space exist for a photon travelling at light speed. ?
Time and space still exist because it takes time for the light to travel a distance, but from the photon’s viewpoint both time and distance are dilated/contracted to 0.
Thanks for the answer, I was just about to post the following link after googling the subject I had not realized you had answered many thanks. https://phys.org/news/2014-05-does-light-experience-time.html
The question was related to what space is and how many dimensions it may have