http://www.xkcd.com/882/

Oh, I mean it’s related to the whole misinterpreting p value thing, it has nothing to do with the above flame war in the comments.

http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser

An apparent “backwards in time causation” is demonstrated in the delayed choice double slit experiment:
(This is a necessarily simplified description)

In the original double slit experiment, sensors are placed at the slits to detect the presence of the photon. If the senors are switched off, you don’t know which slit the photon passed through and, therefore, you see the usual interference pattern. If the sensors are then switched on, you do know which slit the photon passed through and, therefore, you see a scatter pattern on the screen.

In the delayed choice double slit experiment, the detectors are switched on – so that you see a scatter pattern on the screen. Then a device that is capable of erasing the information obtained by these detectors is placed between the double slit and the screen. If the device is switched off, nothing really changes and therefore the scatter pattern remains. If the device is switched on, the information obtained by the detectors is erased and therefore we again see the interference pattern on the screen. So far, no problem.

Finally, and here is where we see the apparent “backwards in time causation”: If you decide to switch the device on but delay that decision untill after the photon has already passed the double slit, you will still get the interference pattern!

In other words, it seems as if your decision to turn on the device acts backwards in time to determine what the photon does at the slits.

“On topic- I would suggest “Consciousness Explained” by Dennett is a good book on this.”

I read it some years ago.

“But we must understand that Dennett starts with a premise (materialism) and makes the best case he possibly can from there. I believe he does an admirable job.”

Likewise.
Dennett is a philosopher and he like his philosophy to be based in science. Hence the materialist perspective.

“The fact that he concludes he if a fictional character is not surprising if you have considered these issues. It might give one pause in accepting the premise, however.”

Not when you realise how real illusions can seem. The alternative to the illusion of self and freewill is dualism, and there is as yet no evidence for a mind separate from and controlling the brain.

“I hope you are high and dry and that all is well.”

The floods are in the north-east (Queensland) and we live in south-east (Victoria) so we are quite safe, thanks. In any case, the entire adjoining township of Lilydale would have to be submerged before we in Mooroolbark would see any effect.

Appartently it is part of the La Nina affect which commenced in May 2010 and is expected to last till May 2011, after which the El Nino effect will again predominate and bring back the droughts and fires. AGW predicts that these extreme weather events are likley to increase with time.

We have actually just emerged out of a 10 year drought which saw the worst fires in the state’s history in Sept 2009 in which 180 people died, 3,500 houses destroyed, and 1 million acres of bushland burned. Since then, the state has been subjected to episodes of minor flooding from time to time but nothing life threatening as in Queensland at the moment. It’s unheard of for our water tanks to be full in mid Summer but that is what we have at the moment.

…oops, Sorry for the derail

On topic- I would suggest “Consciousness Explained” by Dennett is a good book on this.
But we must understand that Dennett starts with a premise (materialism) and makes the best case he possibly can from there. I believe he does an admirable job.
The fact that he concludes he if a fictional character is not surprising if you have considered these issues. It might give one pause in accepting the premise, however.
Of course I guess that would all depend on previous inputs…

Physicists are extending the range of conditions in which quantum effects are observable – but so far they have to use extreme experimental conditions (like close to absolute zero, for example) in order to tease out certain kinds of quantum effects in medium-sized molecules.

Are you aware of the research described here? – http://www.wired.com/wiredscience/2010/02/quantum-photosynthesis/#

Here’s a quote from the article:

*******************

“Two years ago, researchers led by then-University of California at Berkeley chemist Greg Engel found coherence in the antenna proteins of green sulfur bacteria. But their observations were made at temperatures below minus 300 degrees Fahrenheit, useful for slowing ultrafast quantum activities but leaving open the question of whether coherence operates in everyday conditions.

The Nature findings, made at room temperature in common marine algae, show that it does.”

*********************

Talk of ‘quantum biology’ no less.

Bottom line – these quantum effects do not add uncertainty to the statement that information cannot travel back in time to reverse causality.

Bottome line – articles like the one above should warn us about accepting the type of claims you are making at face value!

One weak replication, and three negative replications does not add up to a replicatable study protocol. If Bem is correct than the results should consistently appear in a standardized experiment

Unfortunately, all of the replication attempts I’m aware of (including the one I gave) were not direct replications. For example, the failed replication attempt of the Facilitation of Recall experiment was an online study – obviously not controlling for participants attention to the task. Richard Wiseman, Chris French and Stuart Richie (student at Edinburgh Uni) are attempting a direct replication of the FoR experiment which should be interesting either way!

But this is still so far from macroscopic objects and normal temperatures and environmental interactions that they do not imply that we can extrapolate up to people. The DeBrolie wavelength and decoherence, I think, have something to say about this.

Bottom line – these quantum effects do not add uncertainty to the statement that information cannot travel back in time to reverse causality.

One weak replication, and three negative replications does not add up to a replicatable study protocol. If Bem is correct than the results should consistently appear in a standardized experiment – that is what we mean by replicated. One out of three is not consistent. And further we need to dig down to the quality control of attempted replications – what is the relationship between the quality of the study and he size of any effect.

We are still left with extremely thin evidence for a highly implausible claim. This adds up to – almost certainly wrong.

There is no consensus interpretation of the quantum effects being discussed – they do not necessarily involve reverse causality.

I agree. The very fact that there exists a variety of interpretations of that particular series of physics experiment should caution us against asserting that reverse-causality is impossible. Also consider the fact that the AAAS held a symposium on retrocausation in 2006 (see here for a brief news report – http://legacy.signonsandiego.com/news/science/20060622-9999-lz1c22cause.html )

Further, it is questionable if such quantum experiments have any implications for the behavior of macroscopic objects, like people.

I agree. However, I got the impression that, not long ago, scientists were pooh-poohing the possibility of relatively long lasting coherent states in anything larger than subatomic particles. Yet now we have papers arguing the case for quantum coherence in the photosynthetic apparatus. I guess that time will tell whether quantum effects could theoretically occur during activity of the brain/mind and be functional at the same time. Every time I read a popular science article about QM, the message is – we have so much yet to learn.

I maintain that the effect sizes are small and “tiny” is appropriate. You have to put this into the context of what is being measured – bottom line, they are all small enough to be in the noise.

The forward priming effect size found in Bem’s Experiment 3 had a Cohen’s d value of 0.45, the ‘retro-causal’ effect size found in Experiment 9 was 0.42 and the mean ‘retro-causal’ effect size reported for the high stimulus seekers across all experiments was 0.43. So, the article actually reports some psi effect sizes that are about as large as those reported for a standard, undoubtedly real psychological effect (forward priming).

But at first glance, looks like barely significant results (0.02) and “tiny” effect size of 53.3% again.

Significant nevertheless. That would, by usual standards, qualify it as a replication. As for the ‘tiny’ effect size, the paper does not report SD’s so we can’t estimate Cohen’s d for comparison but the effect appears to be approximately the same as that reported in Bem’s paper. This is what you would expect given that the paper is an attempt at replication. One should also take on board your previous point that the more a protocol has been replicated with similar results, the smaller an effect size we should take seriously.

Also, the “boredom” result was not significant,

This was likely a power issue since the original Bem study used 200 participants and also failed to reach significance over all sessions.

it does not look like they adjusted the stats for multiple analysis.

I’m not sure that controlling for familywise error rate would be necessary here since this was a confirmatory study and the comparisons between the ‘high arousal’ and ‘boring’ stimuli don’t need to be jointly accurate.

Ideally, that study would have used a larger sample.