APOD: Movie: Approaching Light Speed (2011 Oct 18)

[Wolf Kotenberg]

wow ! Far more intense that predicting the motion of a planet orbiting two stars. This calls for an ice cold one in my hands ! I think I am dragging out my 1960's radio Shack light show spark box and put in some new diodes and make it work again. 1N4001's ?????

[deathfleer]

Actually, if you travel nearing the speed of light towards a star and leaving a star, it is like a laser in front of you and something dark behind you, right?

[neufer]

Actually, if you travel nearing the speed of light towards a star and leaving a star, it is like a laser in front of you and something dark behind you, right?

Right.

[Chris Peterson]

Actually, if you travel nearing the speed of light towards a star and leaving a star, it is like a laser in front of you and something dark behind you, right?

Bright in front and dark behind, but nothing related to a laser in any way.

[deathfleer]

Actually, if you travel nearing the speed of light towards a star and leaving a star, it is like a laser in front of you and something dark behind you, right?

Bright in front and dark behind, but nothing related to a laser in any way.

It should be something like a laser, since we are bumping into too many photons if we are about a few light minutes from the star.

[Chris Peterson]

It should be something like a laser, since we are bumping into too many photons if we are about a few light minutes from the star.

How is this like a laser? The light you encounter is neither monochromatic, nor coherent, nor collimated, and it was not produced by stimulated emission. Are you simply equating "bright" to "laser"? If so, that makes no sense, since there is nothing intrinsically bright about a laser light source, and plenty of non-laser sources are brighter than any laser.

[frustrated]

Well yet another botched job at showing these effect! - this time the authors could not be bothered to produce a clear video - Hey - its 480p min these days folks! 720p would be grand. So now our kids will all know that it us fuzzy at the speed of light - groan!

There is no room for this sloppiness when teaching something so misunderstood! How is a lay person suppose to know what is the lesson ,and what its the authors errors and omissions!

[neptunium]

I have a few things to criticize in this video:

1. Why is the screen so fuzzy? I was expecting a higher resolution video, but it was a little hard to make out some of the properties of the figures that were seen;
2. Shouldn't we be moving faster with the next simulation? It seemed like we were going the same speed each time, and that everything was just made distorted. I was thinking that we would move faster with each progressing simulation;
3. Why does the background never change in the space view of earth simulation? Did whoever made the simulation forget to redshift the stars in the background? You would think that even the STARS should appear like laser beam-like objects.

If anyone has answers PLEASE respond, because even the small things can confuse me greatly.

[neufer]

2. Shouldn't we be moving faster with the next simulation? It seemed like we were going the same speed each time, and that everything was just made distorted. I was thinking that we would move faster with each progressing simulation;

There are a number of effects going on:

• 1) aberration
  2) doppler
  3) concentrated light intensity.

These are taken one at a time for clarity.

[deathfleer]

It should be something like a laser, since we are bumping into too many photons if we are about a few light minutes from the star.

How is this like a laser? The light you encounter is neither monochromatic, nor coherent, nor collimated, and it was not produced by stimulated emission. Are you simply equating "bright" to "laser"? If so, that makes no sense, since there is nothing intrinsically bright about a laser light source, and plenty of non-laser sources are brighter than any laser.

OIC, 10Q,
It must be dangerous to travel nearing the speed of light, not only with the lights around, but also the magnetic fields

[Ann]

Guest or tszabeau wrote:

I believe that light, reflected from a handheld mirror would reflect my face if in a faster-than-light craft.

According to Einstein, faster-than-light-craft can't exist.

Now perhaps you say that Einstein was wrong, since some neutrinos were lately seen to travel faster than light in an experiment in Europe. But this is the only experiment ever (out of thousands - some people might say many more than that) that seem to show that Einstein might be wrong. And just recently we were offered an explanation for the one experiment that seemed to show that neutrinos could move faster than light. See the last post here: http://asterisk.apod.com/viewtopic.php?f=31&t=25345. Basically, though, the explanation has to do with the fact that the clocks used to measure the speed of the neutrinos are in orbit:

So from the point of view of a clock on board a GPS satellite, the positions of the neutrino source and detector are changing. "From the perspective of the clock, the detector is moving towards the source and consequently the distance travelled by the particles as observed from the clock is shorter," says van Elburg.

So it may well turn out that the neutrinos didn't travel faster than light after all. And all other experiments ever carried out to test Einstein's theories have always proved that Einstein is correct.

Therefore, according to the very best understanding of science, there can be no such thing as a faster-than-light craft.

Why is it so easy to think that such faster-than-light spacecraft could exist? It's because we've seen them in science fiction shows and movies so many times. Just think of Star Trek and Star Wars. Their spaceships certainly move faster than light, and life goes on as if nothing had happened inside them. You can certainly see your own face in a mirror in those ships.

But to the best of the understanding of science, such spacecraft can't exist. Discussing if you could see your face in a mirror inside such a ship is meaningless, since the ship couldn't exist in the first place.

And if we accept the idea that light itself can't move faster than light, then it remains true that you couldn't see your face in the mirror if it was somehow possible for you to travel faster than light. It remains true that you can't see your face in a mirror unless light moves faster than you do, so that it can first bounce off your face, then hit the mirror, then bounce off the mirror and move back to you. What you are proposing is that light must move faster than you do, even if you are moving faster than light because you are inside a faster-than-light craft.

But the whole concept is impossible.

Ann

[neufer]

...plenty of non-laser sources are brighter than any laser.

Or really!!

(There is nothing you can talk to me about that I don't already know, Chris. )

Click to play embedded YouTube video.

<<The CO₂ laser can be constructed to have CW powers up to hundreds of kilowatts (kW). It is also very easy to actively Q-switch a CO₂ laser by means of a rotating mirror or an electro-optic switch, giving rise to Q-switched peak powers up to gigawatts (GW) of peak power. Because of the high power levels available (combined with reasonable cost for the laser), CO₂ lasers are frequently used in industrial applications for cutting and welding. Because CO₂ lasers operate in the infrared, special materials are necessary for their construction. For high power applications, gold mirrors and zinc selenide windows and lenses are preferred. There are also diamond windows and even lenses in use. Diamond windows are extremely expensive, but their high thermal conductivity and hardness make them useful in high-power applications and in dirty environments. Historically, lenses and windows were made out of salt (either sodium chloride or potassium chloride). While the material was inexpensive, the lenses and windows degraded slowly with exposure to atmospheric moisture.>>

<<On March 18, 2009 Northrop Grumman claimed that its engineers in Redondo Beach had successfully built and tested an electrically powered solid state laser capable of producing a 100-kilowatt beam, powerful enough to destroy an airplane or a tank. According to Brian Strickland, manager for the United States Army's Joint High Power Solid State Laser program, an electrically powered laser is capable of being mounted in an aircraft, ship, or other vehicle because it requires much less space for its supporting equipment than a chemical laser. The U.S. Air Force is currently working on the YAL-1 airborne laser, mounted in a Boeing 747, to shoot down enemy ballistic missiles over enemy territory.>>

Photo by Jacqueline McBride/LLNL [b][color=#0000FF]Inside LLNL's Jupiter Laser Facility, physicist Hui Chen conducts positron experiments on the Titan laser, coupling a high-energy,[/color] [u][color=#FF008F]PETAWATT[/color][/u] [color=#0000FF]short-pulse beam with a kilojoule long-pulse (nanosecond) beam[/color][/b].

---

<<Lawrence Livermore has designed, constructed, and operationed of a series of ever larger, more powerful, and more capable laser systems, culminating in the 192-beam National Ignition Facility (NIF), completed in 2009. NIF aims to create a single 500 terawatt (TW) flash of light that reaches the target from numerous directions at the same time, within a few picoseconds. The design uses 192 individual "beamlets", which are amplified in 48 beamlines containing 16 laser amplifiers per line, each one amplifying four of the beamlets. One of the last steps in the process before reaching the target chamber is to convert the infrared light at 1053 nm into the ultraviolet (UV) at 351 nm in a device known as a frequency converter. These are made of thin sheets cut from a single crystal of potassium dihydrogen phosphate. When the 1053 nm (IR) light passes through the first of two of these sheets, frequency addition converts a large fraction of the light into 527 nm light (green). On passing through the second sheet, frequency combination converts much of the 527 nm light and the remaining 1053 nm light into 351 nm (UV) light. IR light is much less effective than UV at heating the targets, because IR couples more strongly with hot electrons which will absorb a considerable amount of energy and interfere with compressing the target. The conversion process is about 50% efficient, reducing delivered energy to 1.8 MJ.>>

[Rickedk]

Well, hello 240p!

[Billy Bob]

I wish Einstein had had a Mont Blanc to write with instead of a Quill and Ink.

Just imagine the ideas he could have scribed

[bystander]

Astronomy Cast | 2011 Oct 17
Episode 235: Einstein

What can we say about Einstein? Albert Einstein! Lots, actually. In this show we’re going to talk about the most revolutionary physicist… ever. He completely changed our understanding of time, and space, and energy, and gravity. He made predictions about the nature of the Universe that we’re still testing out.

[alphachap]

I am puzzled. The first visual effect I see on acceleration is that the building in the distance appears to move farther away-- but this occurs at v<<c, well before any relativistic effects will be noticible. As it happens, I have a lot of experience with motion at subrelativistic speeds and when you accelerate, things in the distance ahead do not appear to move away.
What is this effect?

v=0.1c is not v<<c

[neufer]

I am puzzled. The first visual effect I see on acceleration is that the building in the distance appears to move farther away-- but this occurs at v<<c, well before any relativistic effects will be noticible. As it happens, I have a lot of experience with motion at subrelativistic speeds and when you accelerate, things in the distance ahead do not appear to move away.
What is this effect?

v=0.1c is not v<<c

Note also the closest thing that one sees here is at least 1 light second away.

When one accelerates on earth towards a rising full moon (~1 light second away) it too should appear to move away due to aberration effects (; assuming that one ignores atmospheric optics and the full moon on the horizon optical illusion).

[late-coming-guest]

According to Einstein, faster-than-light-craft can't exist.

Now perhaps you say that Einstein was wrong, since some neutrinos were lately seen to travel faster than light in an experiment in Europe. But this is the only experiment ever (out of thousands - some people might say many more than that) that seem to show that Einstein might be wrong. And just recently we were offered an explanation for the one experiment that seemed to show that neutrinos could move faster than light. See the last post here: http://asterisk.apod.com/viewtopic.php?f=31&t=25345. Basically, though, the explanation has to do with the fact that the clocks used to measure the speed of the neutrinos are in orbit:

Einstein would have some tutelage to lay down here. His theories offer C as a barrier, but not a limit. Relativity does not prohibit particles or fields to exist at velocities greater than C, rather it disallows bradyons to 'cross' the barrier of light-speed. Similarly, Relativity does not allow for theoretical tachyons to 'cross' into sub-luminal speeds. But strictly speaking, Einstein and his theories do not disagree with a hypothetical faster-than-light object.

Secondly, the latest reports of FTL neutrinos at CERN (while under heavy scrutiny and investigation) are not the first experiment to report similar particles traveling with similar velocities [I can't find my citation, but noticed this fact in reading a number of reports re:CERN]. The results of those do seem to have folded or been dismissed under closer investigation. Also, don't dismiss the fact that in repeatable experiments, radiation can propagate at speeds exceeding C, for example x-rays through various lenses. Here again, this has an understandable and physically accounted for explanation that accords it with Relativity. My point being, Einstein's theories are very delectably the greatest scientific advancement of quite some time, but they are still not full explanation of all phenomena; as our observational capabilities and mathematical descriptions become more refined, science is ready to provide new theory amend old.

[neufer]

Particles Faster Than the Speed of Light? Not So Fast, Some Say
By DENNIS OVERBYE
Published: October 24, 2011

by Elwood H. Smith

---

<<So asks the Irish band the Corrigan Brothers in a new song, “Einstein and the Neutrinos,” that is the latest rollicking riff on news that shocked the scientific world last month.

A group of physicists from Italy claimed they had observed the subatomic particles called neutrinos traveling faster than the speed of light. That, of course, is the cosmic speed limit declared in Albert Einstein’s theory of special relativity in 1905. If they are right — and the jury is still out — Einstein might have some explaining to do. Among other things, a neutrino or anything else that went faster than the speed of light could go backward in time.

Physicists, who are quite sure that in fact E does still equal MC squared — whatever may come of this experiment — have expressed skepticism. But that has not stopped the ghostly neutrinos, which can sail through miles of solid lead with impunity, from achieving a sort of pop culture fame not seen since 1960, when John Updike published a poem about them in The New Yorker:

The Earth is just a silly ball
To them through which they pass
Like dustmaids down a drafty hall
Or photons through a sheet of glass.

Neutrino time-travel jokes have proliferated on the Internet. Example: “We don’t serve faster-than-light neutrinos here,” said the bartender. A neutrino walks into a bar.

The neutrino news came from a group of physicists based at the Gran Sasso underground laboratory in Italy and doing business under the apt acronym Opera. The neutrinos, they reported on Sept. 23 in a paper and at a special symposium at CERN, the European Center for Nuclear Research, had beaten a metaphorical light beam from CERN to Gran Sasso, a distance of 457 miles, by 60 nanoseconds.

The initial response of physicists assembled at CERN and around the world was that there was probably a mistake somewhere in the experiment. Einstein’s theory is the basis of all modern physics, and has been tested a zillion times.

Technically, relativity does allow some particles, known as tachyons, to go faster than light — in fact it forbids them to slow down to light speed. The hitch is that they would have imaginary masses, whatever that means. And there is also the possibility, in some versions of string theory, of particles’ taking a shortcut through another dimension. But allowing anything to travel faster than light would open up the possibility of all kinds of problems with cause and effect and even time travel.

“It looks too big to be true,” Alvaro de Rujala, a CERN theorist, said at the time.

Or as the Corrigan Brothers put it:

Was old Albert wrong?
Oh can it be,
that fabulous theory —
relativity —
is being debunked
for the first time?
But he still might be right,
old Albert Einstein.

Physicists, in the meantime, have been flooding arXiv.org, the physics Internet archive, with papers debunking the Opera experiment and defending Einstein. In one paper, two professors from Boston University, Andrew G. Cohen and the Nobelist Sheldon L. Glashow, showed that if the neutrinos had been going faster than light en route to Gran Sasso, they would have lost energy at a fearsome rate by emitting other particles, causing distortions in the beam that were not seen by Opera.

Another paper — by Gian Giudice of CERN, Sergei Sibiryakov of the Institute for Nuclear Research in Moscow and Alessandro Strumia of the University of Pisa in Italy and the National Institute of Chemical Physics and Biophysics in Tallinn, Estonia — argued that according to the Standard Model, the reigning theory in particle physics, if neutrinos could violate relativity, electrons should violate it also, something that has also not been observed.

Last week, in what sounded like the coup de grâce in some circles, Ronald A. J. van Elburg, an artificial intelligence researcher at the University of Groningen in the Netherlands, suggested that the Opera group had failed to make a relativistic correction for the motions of the GPS satellites used in timing the neutrino beams. The resulting error, he said, amounted to 64 nanoseconds, almost exactly the universe-shaking discrepancy the Opera researchers were hoping to explain.

That paper got wide attention. It was mentioned on a physics blog of the magazine Technology Review, and was published by the Massachusetts Institute of Technology and other news sites around the Internet as a possible explanation of the neutrino mystery. “If it stands up, this episode will be laden with irony,” Technology Review wrote. Far from breaking Einstein’s relativity, it went on, “the faster-than-light measurement will turn out to be another confirmation of it.”

The Opera collaborators and other outside physicists now say Dr. van Elburg’s analysis is wrong and reflects confusion about how GPS systems work. In an e-mail, Antonio Ereditato, a spokesman for Opera, said the paper did have some errors, but he declined to go into details. “You understand well that we cannot reply to anybody claiming to have an explanation of our result in terms of trivial mistakes,” he said. Reached in Groningen, Dr. van Elburg said that an improved version of his manuscript was now under peer review.

John Learned, a neutrino physicist at the University of Hawaii, wrote in an e-mail that while the Opera results might not be right, “they are still not easily dismissed. It is very unlikely to me that any distant observer will point out the error of their ways,” he continued. “If a screw-up, it is probably in the details not accessible to outsiders.”

Meanwhile, Halloween is almost here. Don’t be surprised if you have already seen Einstein in a neutrino costume.>>