Tag: neutrinos

Faster than light Brains on Vacation

By Phil Plait | March 13, 2012 11:04 am

Every month (or so), astronomer Seth Shostak rings me up and we talk about some topic relevant to skepticism for his radio show, "Are We Alone". This month, we talked FTL neutrinos. That is, the latest news in the faster-than-light neutrinos saga.

If you want the background info, you can find it in the Related Posts section below.

Related Posts:

- Unconfirmed rumor: FTL neutrinos may be due to a faulty GPS connection
- New experiment neither proves nor refutes FTL neutrinos
- Followup: FTL neutrinos explained? Not so fast, folks.
- Faster-than-light travel discovered? Slow down, folks

CATEGORIZED UNDER: Cool stuff, Piece of mind, Science

Unconfirmed rumor: FTL neutrinos may be due to a faulty GPS connection

By Phil Plait | February 22, 2012 12:51 pm

Let me start this off by first noting this is an unconfirmed report. We don’t have anything solid yet. Keep that in mind, please!

Via my pal Kiki Sanford comes news that the results of an experiment showing neutrinos moving faster than light (FTL) may have been due to equipment malfunction. Science Insider is reporting, citing unconfirmed sources, that a GPS had a bad connection to a computer, and this caused the timing for the experiment to be thrown off:

According to sources familiar with the experiment, the 60 nanoseconds discrepancy appears to come from a bad connection between a fiber optic cable that connects to the GPS receiver used to correct the timing of the neutrinos’ flight and an electronic card in a computer. After tightening the connection and then measuring the time it takes data to travel the length of the fiber, researchers found that the data arrive 60 nanoseconds earlier than assumed. Since this time is subtracted from the overall time of flight, it appears to explain the early arrival of the neutrinos. New data, however, will be needed to confirm this hypothesis.

Here’s some background. A few months ago, scientists in Europe made a startling announcement: they had measured the velocity of neutrinos, a type of subatomic particle, and found they were moving faster than light. They created a packet of neutrinos in one spot, detected them in another, and then very carefully timed how long the flight took. By dividing the distance by the time, they found that the neutrinos got from Point A to Point B 60 nanoseconds faster than light would!

Obviously, this caused quite the uproar. The scientists involved were careful to state they were’t actually claiming FTL travel, just that they got this result. They also asked for help in figuring it out. Lots of ideas were aired out, and new experiments tried, but in the end timing was always the critical factor. The distance the particles traveled was known to very high accuracy, but the timing was far more difficult to ascertain.

The timing was done using a GPS system, which in theory is accurate enough to do the trick. There are lots of ways you have to be very careful when using GPS, and a lot of folks focused on that. Most of these were pretty high level issues (accounting for relativity, for example), but I never heard anything like "Hey, better try reconnecting that there cable."

To be clear: this is unconfirmed, and still in the rumor stage. If this turns out to be the case, though, then we’re essentially done here. I’ll be very curious to see how this plays out over the next few hours and days. Stay tuned!

Related posts:

- Faster-than-light travel discovered? Slow down, folks
- New experiment neither proves nor refutes FTL neutrinos
- Followup: FTL neutrinos explained? Not so fast, folks.

CATEGORIZED UNDER: Cool stuff, Science

New experiment neither proves nor refutes FTL neutrinos

By Phil Plait | November 21, 2011 7:00 am

On Friday, a news story came out that a second experiment seems to support the results of an earlier experiment which showed neutrinos might be moving faster than light. I commented about this on Google+ at the time, but I want to post about it here as well. Let me be clear: this new result does not confirm FTL neutrinos! What it did was essentially eliminate one possible source of error. A big one still remains.

Let me recap: In September, a team of scientists at CERN working with the OPERA detector in Italy found that beams of neutrinos — subatomic particles that can travel straight through matter — seemed to get from the source in Geneva to the target in Italy 60 nanoseconds faster than a beam of light would make the trip. If true, it means they were moving faster than light (what scifi geeks like me call FTL) which, according to all the physics we understand, is impossible.

There was a lot of criticism of the experiment, as was expected and as it should be! It fell into two broad categories: a problem with the way they created the neutrinos, and a problem with timing.

The neutrinos were created at the accelerator at CERN as bursts containing gazillions of the particles. They move at essentially the speed of light, which is very fast. In fact, while the duration of the burst of neutrinos was very short in human terms, it was still long enough to blur out the results significantly. It’s like standing by the side of the road and trying to figure out when a cluster of cars passes you; do you measure the front of the cluster, the middle, or the tail end? In the case of the neutrinos, they didn’t know which neutrino was which; they measured all of them in the burst and used a statistical method to get an average travel time for each burst.

This is what a second experiment tried to answer. Using a different method the second time around, they were able to significantly tighten up the burst of neutrinos, reducing the error in the measurement by quite a bit. What they found were results consistent with the first experiment: the neutrinos traveled the 743 km trek 60 nanoseconds faster than light.

Holy cow! Does this prove the result?

No. Don’t forget the second source of error: timing. Most people, including me, think that the way they timed the experiment may be the source of the problem. This second experiment used the same timing techniques as the first! So if that’s the source of the error, this doesn’t really change anything.

And either way, we’re left where we were before: with a weird result that cannot really be confirmed or refuted without an independent experiment done by another group. That’s how science works.

I’ll note that another team of scientists has said the FTL results must be wrong due to energy arguments; that may be correct, but I still want to see a wholly separate experiment done. It’s much like nuking the aliens from orbit: it’s the only way to be sure.


Related posts:

- Faster-than-light travel discovered? Slow down, folks
- Followup: FTL neutrinos explained? Not so fast, folks.
- Wall Street Journal: neutrinos show climate change isn’t real
- Followup on the WSJ climate denial OpEd


CATEGORIZED UNDER: Cool stuff, Science, Skepticism, Top Post

Followup: FTL neutrinos explained? Not so fast, folks.

By Phil Plait | October 15, 2011 3:20 pm

If you haven’t heard about the experiment that apparently showed that subatomic particles called neutrinos might move faster than light (what we in the know call FTL, to make us look cooler), then I assume this is your first time on the internet. If that’s the case, then you can read my writeup on what happened.

Basically, neutrinos move very very fast, almost at the speed of light. Some scientists created neutrinos at CERN in Geneva, and then measured how long it took them to reach a detector called OPERA, located in Italy. When they did the math, it looked like the neutrinos actually got there by traveling a hair faster than the speed of light! 60 nanoseconds faster, to be accurate.

Was relativity doomed?

Nope. In fact, relativity may very well be what saves the day here.

First, most scientists were skeptical. Even the people running the experiment were skeptical, and were basically asking everyone else for help. They figured they might have made a mistake as well, and couldn’t figure out what had happened. Relativity is an extremely well-tested theory, and doesn’t (easily) allow for FTL. Despite some headlines screaming that Einstein might be wrong, most everyone figured the problem lay elsewhere.

Most everyone zeroed in on the timing of the experiment, which has to be extremely accurate. The entire flight time of a neutrino from Switzerland to Italy is only about 2.4 milliseconds, and the measurement accuracy needs to be to only a few nanoseconds — mind you, a nanosecond is a billionth of a second!

The scientists used a very sophisticated GPS setup to determine the timing, so that has been the focus of a lot of scrutiny as well. And a new paper just posted on the Physics Preprint Archive may have the answer… and it uses relativity.

Read More

CATEGORIZED UNDER: Cool stuff, Debunking, Science, Skepticism

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