"In the time window of one or two hours during which it is consumed, the wine does not change so much as the wine taster changes. That first taste of wine includes the very slightly painful sensations of heat from the alcohols and pucker from the acids and tannins. As the initial shock dissipates, the taster becomes aware of more subtle complexities. As the wine is consumed, not only does the palate adapt, becoming more tolerant and less sensitive to these stimuli, but the tastebuds and brain also become more and more anesthetized from the ethanol. The wine seems to taste smoother and more complex, when it is in fact the taster´s sensitivities and perceptions that undergo the swiftest and most dramatic change. (see Taste: A User´s Manual)
As far as (especially) big red wines tasting smoother the day after opening, I suspect most of the smoothness comes from the very slight evaporation and reduction in ethanol, the most volatile component, but with this improvement comes also the loss of aromas which have dissipated.
Before you argue against this point, try an experiment (with no deviation or prejudice). It requires two bottles of the same wine, preferably from the same case, two identical decanters, masking tape, a pen, and an assistant (although this exercise is more instructive and fun with additional tasters). The morning of your tasting, open and decant one bottle. Do not open the other bottle. Out of sight, the assistant uses the pen and masking tape to mark each bottle and its corresponding decanter (with a random mark, such as X and O) to keep track. Several hours later, but immediately before tasting and out of sight of the taster(s), he decants the second bottle. The wines are then immediately poured "blind" for the tasters to decide which bottle (decanter) smells and tastes best. Most taster prefer the just-opened bottle most of the time. Furthermore, these results will be consistent, whether using young or aged wines, whether white or red, and whether the tasters are experienced or not.
A great deal of the pleasure of wine comes from smell. The smells in wine are comprised of Volatile Organic Compounds. Some VOCs are present in such minute concentrations and are so volatile that they may be exhausted and disappear completely with only a few seconds of aeration. Is it worth sacrificing these scents for what amounts to superstition that has little scientific basis?
MY ADVICE: If you are unwilling to forgo the "breathing" ritual and you truly place great value in allowing your wines to aerate, simply pulling corks won´t do it. Decant the wine, regardless of an absence of sediment. However, you must keep in mind that the older the bottle of wine, the more brief the aroma window, so gather your friends around to appreciate the fragrances as you decant to remove any sediment and then pour that wine at once!
And, if you are tempted to spend money on one of the many devices on the market that promise "instant breathing" or "accelerated aging", please consider instead purchasing a bottle of Dr. Jim´s Cure-All Snakeoil (its placebo effect is guaranteed to solve all ailments but stupidity) ..."
Just think of the trees: they let the birds perch and fly, with no intention to call them when they come and no longing for their return when they fly away. If people's hearts can be like the trees, they will not be off the Way