Was Crocodile stronger at Marineford? Or was he holding back in Alabasta?

 During the Alabasta arc, Crocodile displayed a level of power that was initially considered overwhelming by the Straw Hat Pirates. He possessed the Logia-type Devil Fruit called the Suna Suna no Mi (Sand-Sand Fruit), which granted him the ability to control and transform into sand. He had a reputation as a Shichibukai and controlled the desert kingdom of Alabasta from the shadows. His strength was showcased through his battles with Luffy and others. At Marineford, Crocodile was present as part of the war that took place at Marine Headquarters. While he did participate in the battle, he didn't display the same level of dominance as some other powerful characters present. This has led fans to speculate that he might not have been as strong as initially portrayed in Alabasta. It's important to note that power scaling and character abilities can be subject to interpretation and development by the author. Oda often keeps details deliberately open-ended to keep the story intriguing.

Time Travel is possible

Greta Thunberg could be a time traveler, claims Twitter | News | DW |  21.11.2019 

This notorious film of an individual obviously chatting on a cellphone in a Charlie Chaplin film is only one sign that time travel is occurring surrounding us. Individuals have seen the past, and the future — and there are huge loads of obvious photos and movies. Here are the most clear indications of genuine time travel. 

The Mouberly-Jourdain episode (or the Ghosts of Petit Trianon) in the nurseries of the Petit Trianon, a little ch√Ęteau situated on the grounds of the Palace of Versailles, France, August 10, 1901

Time Travel Is Possible but Changing the Past Isn't, Study Says

This can be accomplished by going at relativistic paces or through the impacts of gravity. For two indistinguishable clocks moving comparative with one another without speeding up, each clock gauges the other to tick more slow. This is conceivable because of the relativity of synchronization.

How do I travel to the past?

Iranian Scientist Claims to Have Built "Time Machine"

The least difficult way at present being talked about is to take a wormhole (a passage interfacing spatially isolated locales of room time) and give one mouth of the wormhole a considerable speed regarding the other. Section through the wormhole would then permit travel to the past.

 Is it possible to travel faster than light?

Is faster-than-light travel possible? « Kurzweil

General Relativity expresses that reality are combined and that nothing can travel quicker than the speed of light. General relativity likewise depicts how mass and energy twist spacetime – weighty items like stars and dark openings bend spacetime around them.

              What is the proof of E mc2?

In the situation, the expanded relativistic mass (m) of a body times the speed of light squared (c2) is equivalent to the dynamic energy (E) of that body. Brian Greene starts off his Daily Equation video series with Albert Einstein's renowned condition E = mc2

                         Has the time machine been invented?

Iran's future-predicting time machine “actually just a calendar” – The  Pan-Arabia Enquirer

An Iranian researcher has professed to have imagined a 'time machine' that can anticipate the fate of any person with a 98 percent exactness. Chronic innovator Ali Razeghi enrolled "The Aryayek Time Traveling Machine" with Iran's state-run Center for Strategic Inventions,

How fast do you need to travel to go back in time?

  Hey Google: Can We Travel Back in Time? - HeadStuff
  He called it relativity. This hypothesis says that reality are connected together. Einstein likewise said our universe has a speed limit: nothing can travel quicker than the speed of light (186,000 miles each second).

Why does light travel so fast?

      Why is the speed of light the way it is? | SpaceTherefore, light is caused of electromagnetic ripple effects and it goes at that speed, since that is by and large how rapidly influxes of power and attraction travel through space. ... With his unique hypothesis of relativity, Einstein understood the genuine association among existence, a bound together texture known as space-time.

What happens to time at the speed of light?

At the speed of light, what would you see? - YouTube

Time expands on moving vessels: the more prominent the speed, the more noteworthy the time widening. Just when such velocities* approach light speed do such impacts become huge. In the event that, and this one of those limit If's, a vessel could achieve light speed, time on board the vessel would stop by and large.
Is it possible to build a time machine?

Going in time may seem like a trip of extravagant, yet a few physicists figure it may truly be conceivable. BBC Horizon took a gander at the absolute most encouraging
thoughts for transforming this staple of sci-fi into the real world

Ron Mallett has a fantasy: He needs to go on schedule.

This isn't simple dream - Mallett is a regarded educator of physical science.

"I consider myself being a common individual with an energy, and my enthusiasm is the chance of time travel," he says.

Prof Mallett has needed to assemble a time machine for a large portion of his life. His enthusiasm, he clarifies, can be followed to an unfortunate occasion right off the bat in his life.

Ron's dad, a substantial smoker, kicked the bucket of a coronary failure at 33 years old - when Prof Mallett was only 10 years old. Ron was crushed and pulled out into his books.