New controversial theory: Past, present, future exist simultaneously
Our experience of time may be blinding us to its true nature, say scientists.
- Time may not be passing at all, says the Block Universe Theory.
- Time travel may be possible.
- Your perception of time is likely relative to you and limited.
We seem to perceive time as passing in one direction. After all, we can't just just forward to the future or revisit our past if we felt like it. Every minute of every day appears to move us ahead, pulling us through our lives towards an inexorable demise. At least that's what the conventional experience of time tells us. But what if your present, past, and future all existed already? Time, from that point of view, would not flow.
The block universe theory says that our universe may be looked at as a giant four-dimensional block of spacetime, containing all the things that ever happen, explained Dr. Kristie Miller, the joint director for the Centre for Time at the University of Sydney.
In the block universe, there is no "now" or present. All moments that exist are just relative to each other within the three spacial dimensions and one time dimension. Your sense of the present is just reflecting where in the block universe you are at that instance. The "past" is just a slice of the universe at an earlier location while the "future" is at a later location.
So, is time just an elaborate mind trick? And more importantly - is time travel possible?
Dr. Miller's answer to that is "yes". Of course, just hypothetically, since we'd need to figure out first how to travel at "some reasonable percentage of the speed of light". Going to the past would entail using wormholes, like "short cuts through space-time".
Block Universe diagram.Credit: ABC Science
Now, if you did manage to get back in time, you won't be able to change it. This is because your past is always simultaneously someone else's future. So if you travel to the past, you're just making that future the way it is. So don't worry about "grandfather paradoxes" - your time machine has already been incorporated into the scheme of things.
'If I travel to the past, I am part of the past," said Miller. "Importantly, I was always part of the past."
What's more - maybe the past has already been altered by time travelers. How would we be able to tell if it hasn't? "For all we know, the reason the past is the way it is, is in part due to the presence of time travelers," added Miller.
By that logic, what you do tomorrow will make it the way it is, with you fulfilling a certain destiny writ in time, which is in itself more of an illusion than a fundamental property of nature.
Certainly, with such claims, the block universe theory has its detractors. One big criticism is that the future shouldn't exist yet. Physicist Lee Smolin wrote that "The future is not now real and there can be no definite facts of the matter about the future." Furthermore, as he added at a 2017 conference, what is real is just "the process by which future events are generated out of present events."
Another negative of this idea is if the block universe is static, what is the point of anything? Can you have progress? Answering that is the "evolving block universe" model which sees the block of the universal space-time growing rather than staying the same. The surface of such a volume would represent the present moment. It's when "the indefiniteness of the future changes to the definiteness of the past," as described it cosmologist George Ellis. Under that model, the changing part would be the future.
While the debates are going to continue, the block universe theory is one of the most promising approaches that can reconcile the cosmological view of time with our everyday experience. What may be certain - time is much more than what it appears to be. Unraveling its mysteries is integral to understanding the human experience.
What can 3D printing do for medicine? The "sky is the limit," says Northwell Health researcher Dr. Todd Goldstein.
- Medical professionals are currently using 3D printers to create prosthetics and patient-specific organ models that doctors can use to prepare for surgery.
- Eventually, scientists hope to print patient-specific organs that can be transplanted safely into the human body.
- Northwell Health, New York State's largest health care provider, is pioneering 3D printing in medicine in three key ways.
Great ideas in philosophy often come in dense packages. Then there is where the work of Marcus Aurelius.
- Meditations is a collection of the philosophical ideas of the Roman Emperor Marcus Aurelius.
- Written as a series of notes to himself, the book is much more readable than the dry philosophy most people are used to.
- The advice he gave to himself 2,000 years ago is increasingly applicable in our hectic, stressed-out lives.
Can dirt help us fight off stress? Groundbreaking new research shows how.
- New research identifies a bacterium that helps block anxiety.
- Scientists say this can lead to drugs for first responders and soldiers, preventing PTSD and other mental issues.
- The finding builds on the hygiene hypothesis, first proposed in 1989.
Are modern societies trying too hard to be clean, at the detriment to public health? Scientists discovered that a microorganism living in dirt can actually be good for us, potentially helping the body to fight off stress. Harnessing its powers can lead to a "stress vaccine".
Researchers at the University of Colorado Boulder found that the fatty 10(Z)-hexadecenoic acid from the soil-residing bacterium Mycobacterium vaccae aids immune cells in blocking pathways that increase inflammation and the ability to combat stress.
The study's senior author and Integrative Physiology Professor Christopher Lowry described this fat as "one of the main ingredients" in the "special sauce" that causes the beneficial effects of the bacterium.
The finding goes hand in hand with the "hygiene hypothesis," initially proposed in 1989 by the British scientist David Strachan. He maintained that our generally sterile modern world prevents children from being exposed to certain microorganisms, resulting in compromised immune systems and greater incidences of asthma and allergies.
Contemporary research fine-tuned the hypothesis, finding that not interacting with so-called "old friends" or helpful microbes in the soil and the environment, rather than the ones that cause illnesses, is what's detrimental. In particular, our mental health could be at stake.
"The idea is that as humans have moved away from farms and an agricultural or hunter-gatherer existence into cities, we have lost contact with organisms that served to regulate our immune system and suppress inappropriate inflammation," explained Lowry. "That has put us at higher risk for inflammatory disease and stress-related psychiatric disorders."
University of Colorado Boulder
This is not the first study on the subject from Lowry, who published previous work showing the connection between being exposed to healthy bacteria and mental health. He found that being raised with animals and dust in a rural environment helps children develop more stress-proof immune systems. Such kids were also likely to be less at risk for mental illnesses than people living in the city without pets.
Lowry's other work also pointed out that the soil-based bacterium Mycobacterium vaccae acts like an antidepressant when injected into rodents. It alters their behavior and has lasting anti-inflammatory effects on the brain, according to the press release from the University of Colorado Boulder. Prolonged inflammation can lead to such stress-related disorders as PTSD.
The new study from Lowry and his team identified why that worked by pinpointing the specific fatty acid responsible. They showed that when the 10(Z)-hexadecenoic acid gets into cells, it works like a lock, attaching itself to the peroxisome proliferator-activated receptor (PPAR). This allows it to block a number of key pathways responsible for inflammation. Pre-treating the cells with the acid (or lipid) made them withstand inflammation better.
Lowry thinks this understanding can lead to creating a "stress vaccine" that can be given to people in high-stress jobs, like first responders or soldiers. The vaccine can prevent the psychological effects of stress.
What's more, this friendly bacterium is not the only potentially helpful organism we can find in soil.
"This is just one strain of one species of one type of bacterium that is found in the soil but there are millions of other strains in soils," said Lowry. "We are just beginning to see the tip of the iceberg in terms of identifying the mechanisms through which they have evolved to keep us healthy. It should inspire awe in all of us."
Check out the study published in the journal Psychopharmacology.
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