How does gravity bend spacetime?

Time travel is possible, but only in one direction.

KONSTANTIN BATYGIN: In our daily experience we are used to thinking of events as being separated in space and separated in time and there's a true kind of sense of simultaneity, where two things that are separated in space happen in the same time, and we're okay with that. As it turns out, that's only an approximate view of what's really happening. In reality, space and time are strongly intertwined things and the union of them is called spacetime. Now spacetime is the grid if you will of this world. It is the coordinate system on which everything happens. And gravity tends to bend that coordinate system. And so indeed, gravity what we experience as falling, for example if we jump off a little hill or something like that, that is nothing. That is just a manifestation of the fact that spacetime continuum itself is being curved by the gravitational field of the Earth. What does this mean? What does this curving mean? It means that depending on how close you are to the source of gravity, time will pass at different rates. That said, biologically you will not experience it differently one way or another. The only thing that this is useful for is if you wanted to build a time machine.

So a time machine can never go backwards in time, but you can make a time machine that goes forward in time. Suppose you are a fan of some Netflix series and you want to watch the whole thing and you don't want to wait for different seasons to come out one year apart. You just want to binge watch the whole thing now. Then what you do is you build a planet and then you put yourself in the center so that you are experiencing no gravitational field because you are weightless in the center of the planet. You drill a hole and then you put a TV outside of the planet, submerge the TV in the gravitational field so that time passes more rapidly for the TV and then you watch. So, as a biological being you will not experience aging any differently at least due to gravity. You will not experience aging any differently if you live on a mountain or on the surface of the Earth.

  • We typically think of events as happening in space and in time. "In reality, space and time are strongly intertwined things and the union of them is called spacetime," explains Konstantin Batygin.
  • The force that we understand as gravity, according to Batygin, is the result of the spacetime continuum being curved by Earth's gravitational field. Depending on how close you are to the source of gravity, time will pass at different rates.
  • Traveling backward in time is not possible. Traveling forward through time without aging, however, would require going to the center of the planet where the effects of that gravitational field can't be experienced.
For more from Batygin, visit

What does kindness look like? It wears a mask.

Northwell Health CEO Michael Dowling has an important favor to ask of the American people.

Sponsored by Northwell Health
  • Michael Dowling is president and CEO of Northwell Health, the largest health care system in New York state. In this PSA, speaking as someone whose company has seen more COVID-19 patients than any other in the country, Dowling implores Americans to wear masks—not only for their own health, but for the health of those around them.
  • The CDC reports that there have been close to 7.9 million cases of coronavirus reported in the United States since January. Around 216,000 people have died from the virus so far with hundreds more added to the tally every day. Several labs around the world are working on solutions, but there is currently no vaccine for COVID-19.
  • The most basic thing that everyone can do to help slow the spread is to practice social distancing, wash your hands, and to wear a mask. The CDC recommends that everyone ages two and up wear a mask that is two or more layers of material and that covers the nose, mouth, and chin. Gaiters and face shields have been shown to be less effective at blocking droplets. Homemade face coverings are acceptable, but wearers should make sure they are constructed out of the proper materials and that they are washed between uses. Wearing a mask is the most important thing you can do to save lives in your community.
Keep reading Show less

Scientists stumble across new organs in the human head

New cancer-scanning technology reveals a previously unknown detail of human anatomy.

Credit: Valstar et al., Netherlands Cancer Institute
Surprising Science
  • Scientists using new scanning technology and hunting for prostate tumors get a surprise.
  • Behind the nasopharynx is a set of salivary glands that no one knew about.
  • Finding the glands may allow for more complication-free radiation therapies.
Keep reading Show less

Millennials reconsidering finances and future under COVID-19

A new survey found that 27 percent of millennials are saving more money due to the pandemic, but most can't stay within their budgets.

Personal Growth
  • Millennials have been labeled the "unluckiest generation in U.S. history" after the one-two financial punch of the Great Recession and the pandemic shutdowns.
  • A recent survey found that about a third of millennials felt financially unprepared for the pandemic and have begun saving.
  • To achieve financial freedom, millennials will need to take control of their finances and reinterpret their relationship with the economy.
  • Keep reading Show less

    Science confirms: Earth has more than one 'moon'

    Two massive clouds of dust in orbit around the Earth have been discussed for years and finally proven to exist.

    J. Sliz-Balogh, A. Barta and G. Horvath
    Surprising Science
    • Hungarian astronomers have proven the existence of two "pseudo-satellites" in orbit around the earth.
    • These dust clouds were first discovered in the sixties, but are so difficult to spot that scientists have debated their existence since then.
    • The findings may be used to decide where to put satellites in the future and will have to be considered when interplanetary space missions are undertaken.
    Keep reading Show less

    6 easy ways to transition to a plant-based diet

    Your health and the health of the planet are not indistinguishable.

    Credit: sonyakamoz / Adobe Stock
    Personal Growth
    • Transitioning to a plant-based diet could help reduce obesity, cardiovascular disease, and type 2 diabetes.
    • Humans are destroying entire ecosystems to perpetuate destructive food habits.
    • Understanding how to properly transition to a plant-based diet is important for success.
    Keep reading Show less